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2ddac97c77
* feat: implement Redis job queue and fakeredis support
- Refactored the job queue service to support Redis-backed management for cross-worker scaling.
- Added environment variables for configuration:
- `LANGFLOW_JOB_QUEUE_TYPE=redis`
- `LANGFLOW_REDIS_QUEUE_DB=1`
- Updated job ownership methods to be asynchronous for improved concurrency handling.
- Enhanced Redis cache service with namespacing via key prefixes.
- Introduced `fakeredis` for in-memory Redis simulation in testin>
- Added comprehensive unit tests for Redis job queue components.
* fix: run experimental warning for RedisCache usage only once
- Introduced a mechanism to emit a one-time warning for the RedisCache experimental feature during server runtime.
- The warning is logged only if no other worker has already emitted it, ensuring clarity for users regarding the experimental status of RedisCache.
- The implementation includes a temporary file check to prevent multiple warnings across different processes.
* docs: document environment variables for worker management
- Added documentation for LANGFLOW_GUNICORN_PRELOAD to explain preloading for better performance.
- Detailed the use of LANGFLOW_JOB_QUEUE_TYPE for specifying backends (e.g., Redis).
- Included LANGFLOW_REDIS_QUEUE_DB to define the database index for job queues.
- Updated the "High-Load Environments" guide with these optimal configurations.
* docs: updated 'High-load and multi-worker environments' section
* feat: enhance RedisJobQueueService with consumer wrapper management
- Introduced a caching mechanism for Redis stream consumers to optimize job data retrieval.
- Added methods to manage consumer wrappers, ensuring they are reused across sequential polls.
- Implemented cleanup logic to cancel and clear consumer wrappers during job cleanup and service stop.
- Expanded unit tests to verify consumer wrapper reuse and cleanup behavior.
* fix: ensure Redis keys are deleted during job cleanup even on cancellation
- Updated the cleanup_job method in RedisJobQueueService to guarantee Redis keys are removed even if the job cleanup is interrupted by a CancelledError.
- Added a new unit test to verify that Redis keys are deleted correctly when cleanup is called during task cancellation.
* fix: manage connection check task in RedisJobQueueService
- Added handling for the connection check task in the stop method to ensure it is properly cancelled and awaited if still running.
- This change improves resource management and prevents potential issues during service shutdown.
* fix: handle unpublished sentinel requeue on cancellation in RedisJobQueueService
- Updated the job processing logic to ensure that if a job is cancelled during the xadd operation, the unpublished sentinel is requeued instead of being dropped.
- Introduced a new unit test to verify this behavior, ensuring robustness in job handling during cancellations.
* fix: improve Redis job queue service with enhanced configuration and cleanup
- Added atexit cleanup to remove stale temporary files for RedisCache.
- Refactored Redis job queue service to use shared constants for stream prefixes, improving maintainability.
- Updated type hints for better clarity and consistency in RedisQueueWrapper and RedisJobQueueService.
- Enhanced error handling with configurable backoff for transient read failures.
* fix: enhance Redis job queue service with maxlen configuration for xadd
- Updated the xadd method in RedisJobQueueService to include maxlen and approximate parameters, improving stream management and preventing excessive memory usage.
* fix: enhance job ownership retrieval in RedisJobQueueService
- Updated the get_job_owner method to refresh the Redis key TTL on successful lookups, ensuring long-running jobs maintain their ownership anchor.
- Improved code clarity by extracting the owner key into a variable and adding detailed docstring explanations for better understanding of the TTL management.
* fix: improve job ownership handling in cleanup_job method
- Enhanced the cleanup_job method in RedisJobQueueService to accurately capture job ownership before deleting Redis keys, preventing potential data corruption in multi-worker scenarios.
- Added comments for clarity on ownership logic and its implications during job cleanup.
* fix: optimize TTL management in RedisJobQueueService
- Introduced periodic TTL refresh logic in the _bridge_to_redis method to enhance Redis stream management, reducing round-trips and improving throughput.
- Added constants for TTL refresh events and seconds to maintain clarity and configurability.
- Updated event handling to ensure TTL is refreshed appropriately based on event count and time elapsed.
* fix: improve event handling in flow response management
- Removed unnecessary error handling for missing event tasks in get_flow_events_response, allowing for smoother operation when no task exists.
- Updated create_flow_response to handle optional event_task parameter, ensuring proper cleanup during disconnections.
- Added unit tests to verify behavior when event tasks are missing, enhancing robustness in streaming scenarios.
* fix: enhance RedisQueueWrapper with startup grace period and stream observation
- Added a startup grace period to prevent premature end-of-stream signals when the producer has not yet issued its first XADD.
- Introduced a flag to track whether the stream has been observed, improving the handling of early polling scenarios.
- Updated logic to ensure proper handling of stream existence checks and logging for better debugging during job processing.
* fix: implement cleanup for old cross-worker job queues in RedisJobQueueService
- Added a new method to clean up done cross-worker consumer wrappers that are not owned by the current worker, ensuring proper resource management.
- Enhanced the existing cleanup logic to prevent memory leaks by explicitly pruning stale entries from the consumer wrappers dictionary.
- Improved logging to provide better visibility into the cleanup process for cross-worker jobs.
* fix: enhance job handling in JobQueueService with guarded task execution
- Updated the start_job method to accept a Coroutine type for task_coro, ensuring type safety.
- Introduced a new _guarded_task method to wrap job coroutines, guaranteeing that unhandled exceptions emit an error event and write a sentinel to the Redis Stream, improving reliability in job processing.
- Enhanced documentation to clarify the behavior of the new task handling mechanism and its implications for cross-worker consumers.
* fix: improve client disconnection handling in create_flow_response
- Added logging for scenarios where a client disconnects without an associated event_task, clarifying that the producer will continue running until the build completes.
- Documented the limitation regarding cross-worker passive disconnects and the need for a Redis side-channel for proper cancellation, enhancing observability in the logs.
* fix: enhance RedisQueueWrapper to manage initial read state and buffer behavior
- Introduced a flag to track the completion of the first XREAD call, ensuring proper buffer management during the initial read phase.
- Updated the empty method to reflect the state of the buffer accurately, preventing premature exits from the drain loop until the first read is complete.
- Improved documentation to clarify the behavior of the new flag and its impact on job processing.
* fix: clarify RedisQueueWrapper behavior in tests for buffer state and no-op operations
- Updated test documentation to explain the behavior of the empty() method in relation to the first XREAD completion, ensuring accurate understanding of buffer state during job processing.
- Adjusted assertions in tests to reflect the intended behavior of the RedisQueueWrapper, specifically regarding the no-op nature of put_nowait and its impact on the internal buffer.
* fix: update dependencies in pyproject.toml and uv.lock
- Added fakeredis dependency with a minimum version of 2.0.0 to both pyproject.toml and uv.lock files.
- Ensured proper formatting and comments in pyproject.toml for clarity on onnxruntime version constraints.
* feat(job_queue): cross-worker cancel via Redis pub/sub + configurable startup grace
- Add LANGFLOW_REDIS_QUEUE_STARTUP_GRACE_S (default 30.0) so deployments
with slow producer-worker cold-start can bump the wrapper's early-poll
grace period without editing code.
- Add LANGFLOW_REDIS_QUEUE_CANCEL_CHANNEL_ENABLED (default True) wiring a
per-job Redis pub/sub channel (langflow:cancel:<job_id>) so
POST /build/{job_id}/cancel works cross-worker. The producer subscribes
when the job starts; any worker can publish via
RedisJobQueueService.signal_cancel and the subscriber cancels the local
build task on receipt.
- cancel_flow_build now falls back to signal_cancel when event_task is
None on this worker, replacing the previous no-op for cross-worker
cancellation.
- Subscriber tasks are tracked in _cancel_subscribers and torn down in
cleanup_job/stop alongside the bridge tasks.
- Tests: 3 new unit tests covering cross-worker signal propagation, the
disabled-flag no-op, and the wrapper's per-instance startup_grace_s
override.
* fix(job_queue): close three cross-worker cancel corner cases
Discovered by a deeper local stress pass over the prototype:
1. **Signal-before-subscribe race**: publish from worker A would be lost if
worker B's subscriber had not finished SUBSCRIBE yet. signal_cancel now
also sets a short-lived langflow:cancel-marker:<job_id> key, and the
subscriber checks it immediately after subscribing — so a cancel that
raced the SUBSCRIBE still fires.
2. **Restart subscriber leak**: start_job called twice for the same job_id
silently overwrote the dict entry and orphaned the previous subscriber
(and its Redis pubsub connection). Now cancels the previous subscriber
before storing the new one.
3. **Slow end-of-stream after cross-worker cancel**: cancelling the local
task did not unblock cross-worker consumers — the bridge sat waiting on
local_queue.get() until periodic cleanup ran ~5 min later. The
subscriber now puts a sentinel on the local queue after task.cancel()
so the bridge flushes a clean end-of-stream marker to Redis. Measured
8ms from signal_cancel to consumer end-of-stream against real Redis.
Tests: 3 new unit tests covering each corner case; 9-scenario local
stress harness against real Redis confirms all green.
* refactor(job_queue): address self-review of cross-worker cancel
Addresses the eight points from the PR review of the previous commits:
1. Configurable marker TTL — new LANGFLOW_REDIS_QUEUE_CANCEL_MARKER_TTL
setting (default 60s) replaces the hardcoded constant.
2. Connection-pool footprint is O(1) in active jobs — replaced the per-job
pub/sub subscriber with a single PSUBSCRIBE dispatcher per worker
listening on langflow:cancel:*.
3. Prompt stream cleanup after cancel — the dispatcher now waits for the
bridge to drain the sentinel before triggering cleanup_job, so the
Redis stream + owner keys are deleted within milliseconds instead of
waiting for the 5-minute periodic cleanup grace.
4. signal_cancel raises on Redis failure — publish errors propagate to the
caller instead of silently returning 0. The cancel HTTP endpoint
catches and returns False so the client can retry.
5. Auth note in signal_cancel docstring — explicit note that callers must
verify authorization; the HTTP cancel endpoint already does via
_verify_job_ownership before calling through.
6. Structured cancel logging — INFO-level logs on publish, marker hit,
owned dispatch, foreign dispatch. _cancel_stats counters expose
{published, marker_hit, dispatched_owned, dispatched_foreign,
publish_errors} for ops/metrics.
7. redis-py version compatibility — _close_pubsub falls back from
aclose() to close(), handles both sync and async return values.
8. Fire-and-forget tasks hold strong references — _background_tasks set
keeps marker checks and post-cancel cleanups from being GC'd before
they run; each task self-removes via add_done_callback. stop() drains
the set on shutdown.
Tests: 24 passing (1 skipped due to timing); deep stress harness verified
6 scenarios against real Redis.
* feat(job_queue): propagate client disconnect via signal_cancel for cross-worker builds
Closes the remaining cross-worker passive-disconnect gap. Previously, when a
client closed its streaming connection on a non-owner worker, the producer
worker kept emitting events until the build completed naturally. Now the
disconnect handler in create_flow_response publishes a cross-worker cancel
via signal_cancel so the owning worker stops promptly.
- create_flow_response accepts optional queue_service + job_id kwargs and
uses them in on_disconnect for the cross-worker case (event_task is None).
Both are keyword-only and default to None, preserving the single-worker
contract.
- get_flow_events_response wires both through.
- New unit test test_cross_worker_disconnect_publishes_signal_cancel covers
the full pubsub propagation path with two services sharing a fake Redis.
- Tested end-to-end against real Redis with a two-worker harness: 10/10
scenarios pass, including the new disconnect propagation case.
* feat(job_queue): production-harden cross-worker cancel for multi-worker setups
Five complementary improvements that make the Redis-backed cancel/lifecycle
path safe to leave running unattended under real ops pressure.
A. Dispatcher reconnect loop with exponential backoff. _run_cancel_dispatcher
used to exit silently on any Redis-side error (broker restart, network
blip, listen() hiccup), leaving the worker permanently blind to
cross-worker cancels until process restart. The loop now reconnects with
capped backoff (max 30s), and a dispatcher_reconnects counter exposes the
event for monitoring.
B. Outer timeout on _post_cancel_cleanup. The background cleanup task could
hang indefinitely if cleanup_job stalled (Redis pathology during DELETE);
wrap in asyncio.wait_for and let periodic cleanup retry instead.
C. Public metrics_snapshot() on JobQueueService (memory + Redis backends)
plus GET /monitor/job_queue endpoint behind get_current_active_user.
Surfaces backend, active_jobs, bridge_count, consumer_wrapper_count,
background_task_count, cancel_dispatcher_running, and the full
cancel_stats counter set.
D. Deterministic rewrite of test_redis_service_signal_cancel_flushes_sentinel_to_consumer.
The previous version was skipped roughly half the time due to a fakeredis
timing race; the new version no-ops cleanup_job for the duration of the
assertion so the bridge XADD ordering can be observed reliably. No more
skipped tests in the suite (33 pass, 0 skip).
E. Polling-mode stale-client watchdog. Polling has no persistent connection
for on_disconnect, so abandoned polling builds previously ran to natural
completion even after the client gave up. New flow:
* touch_activity(job_id) writes langflow:activity:<job_id> on every poll
and on streaming-response open; consume_and_yield refreshes it every
10s while the connection is held.
* _run_polling_watchdog scans owned jobs every
LANGFLOW_REDIS_QUEUE_POLLING_WATCHDOG_INTERVAL_S (default 15s) and
publishes signal_cancel for jobs whose activity is older than
LANGFLOW_REDIS_QUEUE_POLLING_STALE_THRESHOLD_S (default 90s).
* Streaming clients are protected by the heartbeat refresh; threshold <=
0 disables the watchdog entirely.
* cleanup_job folds the activity key into the existing DEL round-trip
so successful builds clean up after themselves.
End-to-end coverage: 33 unit tests pass (up from 25, with the previous skip
now passing deterministically); a two-worker real-Redis harness exercises 12
scenarios including dispatcher reconnect, post-cancel timeout, watchdog
reclamation, and metrics_snapshot schema completeness.
* fix(job_queue): address PR review + Codex adversarial review findings
Acts on every must-fix finding from a multi-agent review pass (code-reviewer,
pr-test-analyzer, silent-failure-hunter, comment-analyzer) plus the Codex
adversarial review. No behavior is left to chance under realistic operational
conditions.
Critical fixes:
- Streaming heartbeat now runs as an INDEPENDENT task for the lifetime of the
response, not coupled to event yield cadence. A quiet build (long graph
step, slow LLM, no tokens for a while) previously had no heartbeat path, so
the polling watchdog could reclaim a live streaming client after the
threshold. The new heartbeat fires every streaming_activity_refresh_s
regardless of queue activity, and is cancelled cleanly on both
on_disconnect AND natural stream end.
- Watchdog start-grace window. A new in-memory _job_start_times[job_id]
timestamp is set in start_job() BEFORE super().start_job() so a job can
never appear in self._queues without a corresponding start time. When the
watchdog scans and the Redis activity key is missing, it skips the kill
until (now - start_ts) >= threshold. Without this, a slow background
touch_activity (event-loop pressure, Redis blip) could nuke a brand-new
build on the very first watchdog tick — the prior code's comment promised
the guard but didn't implement it.
- touch_activity errors are now observable. Replaces a blanket
contextlib.suppress(Exception) with an explicit try/except that bumps
activity_touch_errors and emits a debug log. CancelledError is no longer
swallowed. Operators get a signal when the heartbeat is silently failing.
- Watchdog UnboundLocalError closed. Initializes last = 0.0 before the
raw-is-None branch so a malformed activity value (parse failure) can't
crash the entire watchdog task. Adds activity_parse_errors and
activity_get_errors counters.
- Dispatcher except is split: ConnectionError/TimeoutError/OSError stay at
awarning (transient Redis), every other Exception goes to aerror with
exc_info=True AND increments dispatcher_internal_errors. Code bugs in
_handle_cancel no longer look identical to Redis disconnects.
- _post_cancel_cleanup narrows the bridge-wait suppress to TimeoutError
only, with a dedicated awarning naming the consequence ("cross-worker
consumers may see late end-of-stream"). Real bridge failures bubble up
via a separate Exception arm with awarning instead of being silent.
- Polling watchdog uses local _handle_cancel for owned jobs instead of
round-tripping through pubsub. Faster (no Redis RTT), dispatcher-
independent (works during a reconnect backoff), and keeps the
cancel_stats["published"] counter honest as a count of *external* cancels.
- /monitor/job_queue gated to get_current_active_superuser instead of
get_current_active_user — the snapshot exposes process-wide tenant
workload + cancel activity, which matters in multi-tenant deployments.
Docstring corrections:
- Removed the "cross-worker cancel is a known limitation" remnant from
RedisJobQueueService.get_queue_data — the limitation was closed in the
prior commit, and the new docstring tells callers exactly how cross-worker
cancel travels (signal_cancel → dispatcher).
- touch_activity docstring rewritten. The previous text described a
"TTL-based reasoning" fallback that didn't exist; the new text correctly
explains the 4x-threshold TTL and how it interacts with the watchdog's
start-time grace window.
New tests (5 added, total 38 pass):
- test_polling_watchdog_grants_start_grace_window: brand-new job with
deleted activity key survives until the threshold passes, then dies.
- test_polling_watchdog_skips_malformed_activity_value: malformed value
bumps activity_parse_errors and does NOT kill the job.
- test_streaming_heartbeat_runs_independent_of_event_yield: quiet streaming
build is not reclaimed; heartbeat task is cancelled on disconnect.
- test_concurrent_cancels_from_multiple_workers_are_idempotent: two workers
publish cancel simultaneously, no crashes, single observable cancel.
- test_dispatcher_internal_error_logged_at_error_level: bug in
_handle_cancel bumps dispatcher_internal_errors and dispatcher_reconnects;
the dispatcher task is still running afterwards.
Plus: test_metrics_snapshot_exposes_cancel_stats_and_counters now pins the
full cancel_stats key set (using set equality), so adding an increment
without registering the key — or vice versa — fails the test instead of
producing a silent KeyError in production.
End-to-end coverage: 38 unit tests pass; the two-worker real-Redis harness
passes all 12 scenarios on commit HEAD.
* fix: harden redis job queue cancellation
* feat(job_queue): seamless redis setup + actionable errors for unsupported delivery
- RedisQueueWrapper: restore _BUFFER_MAXSIZE bounded buffer and the
_on_fill_done done-callback safety net that release-1.10.0 added in #12588,
so a slow consumer cannot grow the buffer without bound and a crashing or
cancelled _fill_task cannot leave consumers stuck on await get().
- build.get_flow_events_response: explicit exhaustiveness guard. Unknown
EventDeliveryType values now return HTTP 400 with the supported set and a
remediation hint instead of silently falling through to the polling path.
- lfx settings.set_event_delivery: when workers > 1 without a redis queue,
upgrade the warning to name the requested mode, the forced fallback, and
the LANGFLOW_JOB_QUEUE_TYPE env var that would preserve the original mode.
- Tests: port the three RedisQueueWrapper safety tests from release-1.10.0
and add coverage for the new event_delivery guard.
* fix(job_queue): polling watchdog only watches jobs with a registered owner
Surfaced by locust load testing on a Redis-queue, 2-worker setup:
2016 requests / 2016 polling_watchdog_kills (1:1 ratio)
TaskService.launch_task uses JobQueueService.start_job for server-internal
tasks (telemetry, background work) without calling register_job_owner.
These tasks never refresh the activity heartbeat because no polling
client is involved, so the watchdog's start-time fallback was killing
every single one once it crossed polling_stale_threshold_s.
Under fast-completing flows the user-visible result was unaffected (the
build finished before the watchdog struck) — but a long-running internal
task (slow LLM call, retrieval, etc.) would be cancelled mid-flight even
though no one was waiting on it.
Scope the watchdog to jobs in self._job_owners: user-facing flow builds
register an owner; TaskService tasks don't. After this change the same
locust run reports polling_watchdog_kills=0 and dispatched_owned=0.
Existing watchdog tests register an owner explicitly to mirror the real
flow path. Adds a regression test (TaskService-style start_job with no
owner must not be reclaimed).
* test(job_queue): add coverage for fixes surfaced by load testing
Three regression tests for the recent fixes:
- TaskService integration: launch a task through
TaskService.fire_and_forget_task and assert the polling watchdog
leaves it alone (no owner registered, no kill). Catches a future
regression where someone adds register_job_owner inside TaskService.
- Settings multi-worker warning: verify Settings.set_event_delivery
warns with the requested mode AND names LANGFLOW_JOB_QUEUE_TYPE in
the fallback log when workers > 1 and the job queue is in-memory.
An operator seeing missing events needs that env var name to fix it.
- Bounded buffer backpressure: floods the fill task past the maxsize
ceiling and verifies qsize() never exceeds _BUFFER_MAXSIZE. The
previous test only asserted the constant, not the behavior.
Skipped two suggested tests:
- TestClient version of the unknown-event_delivery guard: FastAPI's
enum validation returns 422 before our handler runs, so HTTP cannot
reach the defensive 400. The existing unit test is the right test.
- Exact watchdog kill-count assertion (== 1): the watchdog can tick
again before cleanup_job removes the job from _queues, making any
exact-count check flaky on slow CI. The existing >= 1 is correct.
* fix(job_queue): use asyncio.create_task for trace cleanup on cancel
background_tasks.add_task() is silently dropped after FastAPI drains
the POST /build response queue — by the time any cancel fires (local,
cross-worker pub/sub, or polling watchdog), the task list from the
original HTTP request is already consumed.
Replace the background_tasks call in _run_vertex_build's CancelledError
handler with asyncio.create_task(graph.end_all_traces_in_context()())
so the trace cleanup runs as an independent task regardless of the
background_tasks lifecycle.
Adds a regression test that exercises generate_flow_events end-to-end:
a blocking vertex is cancelled mid-flight and the test asserts that
end_all_traces is eventually called via the spawned task.
* [autofix.ci] apply automated fixes
* fix: addresses a few pr review findings (#13179)
* fix(job_queue): address PR review findings from cross-worker cancel implementation
- Restore _last_id cursor update to after await buffer.put() in _fill_from_redis;
advancing before the await loses the event if the task is cancelled while put()
is blocked on a full buffer
- Restore XREAD persistent-error grace period: track elapsed error time and deliver
an end-of-stream sentinel after _STARTUP_GRACE_S of continuous failures instead
of looping forever, which left consumers stuck on await get()
- Fix cancel_flow_build returning True when no task and no signal_cancel (in-memory
backend); return False to correctly signal that cancellation did not take effect
- Decouple polling watchdog from cancel_channel_enabled; the watchdog uses only
local state and _handle_cancel with no pub/sub dependency, so disabling the
cancel channel must not silently disable stale-client reclamation
- Restore _BUFFER_MAXSIZE to 1000 (reverts unexplained 10x increase to 10_000)
* test(job_queue): add regression coverage for PR review fixes
- test_fill_from_redis_last_id_not_advanced_before_put_completes: verifies
the XREAD cursor (_last_id) stays at the prior message's position when the
fill task is cancelled while put() is blocked on a full buffer
- test_fill_from_redis_persistent_xread_error_delivers_sentinel: verifies a
persistent XREAD failure eventually delivers the end-of-stream sentinel
after _STARTUP_GRACE_S of continuous errors (not an infinite retry loop)
- test_cancel_flow_build_returns_false_for_in_memory_backend_without_task:
verifies cancel_flow_build returns False when no local task exists and the
queue service has no cross-worker cancel path
- test_polling_watchdog_runs_when_cancel_channel_disabled: verifies the
polling watchdog reclaims stale jobs even when cancel_channel_enabled=False
* format and comment updates
* comments
* [autofix.ci] apply automated fixes
---------
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
* fix(job_queue): address CodeRabbit review findings
- cancel_flow_build: gate signal_cancel on a new cross_worker_cancel_enabled
property so Redis with cancel_channel_enabled=False is treated the same as
the in-memory backend (signal_cancel short-circuits to 0 without setting
the marker, so the previous unconditional return True was misleading).
- _run_vertex_build: hold a strong reference to the trace cleanup task on
CancelledError (Ruff RUF006). Tasks self-discard via add_done_callback.
- RedisQueueWrapper.finish_with_sentinel: stop awaiting on a bounded buffer
during teardown. Evict + put_nowait mirrors _on_fill_done so shutdown can
no longer hang on a slow or abandoned consumer.
- RedisJobQueueService.cleanup_job: wrap the Redis DEL in try/except so
Redis failures during teardown surface as warnings instead of escaping
stop() and explicit cancel paths.
- Settings (lfx): add Field bounds on the new Redis timing knobs so a
negative startup_grace_s or non-positive cancel_marker_ttl /
watchdog_interval_s fails fast at config load instead of silently
reopening races.
- Streaming heartbeat interval: lift to module-level STREAMING_ACTIVITY_REFRESH_S
so the heartbeat test can monkeypatch it.
Tests:
- _make_service tracks shared_client ownership so the first _stop_service
doesn't aclose the FakeRedis under a sibling worker in cross-worker tests.
- test_polling_watchdog_skips_fresh_activity now registers a job owner;
without it the watchdog skips the job entirely and the test would pass
even with a broken touch_activity.
- test_streaming_heartbeat_runs_independent_of_event_yield patches the
interval down and waits for the spawned task to refresh the activity
timestamp, instead of calling touch_activity manually.
- Fix Ruff ARG001, EM101, TRY003, PT018 in test stubs.
* test(job_queue): cover behavior changes from CodeRabbit review fixes
- test_cancel_flow_build_returns_false_for_redis_with_disabled_cancel_channel:
Redis with cancel_channel_enabled=False has signal_cancel but no marker
delivery; cancel_flow_build must report failure, not false success.
- test_finish_with_sentinel_does_not_hang_on_full_buffer: regression cover for
the await-on-bounded-buffer hang. Fills the buffer to capacity and asserts
finish_with_sentinel returns within a tight budget.
- test_redis_service_cleanup_swallows_redis_delete_error: proxies a FakeRedis
whose delete() raises; cleanup_job must absorb it and complete local
teardown.
- test_redis_queue_bounds (lfx): pydantic ValidationError on negative
startup_grace_s / non-positive cancel_marker_ttl /
polling_watchdog_interval_s; zero remains valid for startup_grace_s and
polling_stale_threshold_s (documented disable switch).
* log updates
* [autofix.ci] apply automated fixes
* test(cors): accept both '*' and ['*'] for Python 3.14 compatibility
pydantic-settings parses LANGFLOW_CORS_ORIGINS='*' as the raw string '*'
on Python 3.13 but as ['*'] (a single-element list) on Python 3.14+. The
`str | list[str]` union on Settings.cors_origins resolves differently
between versions, but both shapes carry the same 'all origins' semantic.
Updates two assertions in test_security_cors.py that previously required
the exact string form and were failing on Group 4 / Python 3.14 in CI:
- test_default_cors_settings_current_behavior
- test_wildcard_with_credentials_allowed_current_behavior
The PR itself (cross-worker cancel + polling watchdog) is unrelated to
CORS handling -- the failure is a Python-3.14-introduced incompatibility
in this pre-existing test that happens to surface against this branch's
CI matrix.
* [autofix.ci] apply automated fixes
---------
Co-authored-by: Arek Mateusiak <arek@a4bits.com>
Co-authored-by: Jordan Frazier <122494242+jordanrfrazier@users.noreply.github.com>
Co-authored-by: Jordan Frazier <jordan.frazier@datastax.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
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---
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title: Environment variables
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slug: /environment-variables
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---
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import Tabs from '@theme/Tabs';
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import TabItem from '@theme/TabItem';
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import Link from '@docusaurus/Link';
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|
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In general, environment variables, like `LANGFLOW_PORT` or `LANGFLOW_LOG_LEVEL`, configure how Langflow runs.
|
||
These are broad settings that apply to your entire Langflow deployment.
|
||
|
||
In contrast, global variables are user-defined values stored in Langflow's database for use in flows, such as `OPENAI_API_KEY`.
|
||
Langflow can also source global variables from environment variables.
|
||
For more information, see [Langflow global variables](/configuration-global-variables).
|
||
|
||
## Configure environment variables for Langflow OSS
|
||
|
||
Langflow recognizes [supported environment variables](#supported-variables) from the following sources:
|
||
|
||
- Environment variables set in your terminal.
|
||
- Environment variables imported from a `.env` file when starting Langflow.
|
||
- Environment variables set with the [Langflow CLI](./configuration-cli), including the `--env-file` option and direct options, such as `--port`.
|
||
|
||
You can choose to use one or more of these sources.
|
||
|
||
### Precedence {#precedence}
|
||
|
||
If the same environment variable is set in multiple places, the following hierarchy applies:
|
||
|
||
1. Langflow CLI options override all other sources.
|
||
2. The `.env` file overrides system environment variables.
|
||
3. System environment variables are used only if not set elsewhere.
|
||
When running a Langflow Docker image, the `-e` flag can be used to set additional system environment variables.
|
||
|
||
For example:
|
||
|
||
* If you set `LANGFLOW_PORT=8080` in your system environment and `LANGFLOW_PORT=7860` in `.env`, Langflow uses `7860` from `.env`.
|
||
* If you use the Langflow CLI to run `langflow run --env-file .env --port 9000`, and you set `LANGFLOW_PORT=7860` in `.env`, then Langflow uses `9000` from the CLI option.
|
||
|
||
### Set environment variables in your terminal {#configure-variables-terminal}
|
||
|
||
Run the following commands to set environment variables for your current terminal session:
|
||
|
||
<Tabs>
|
||
<TabItem value="linux-macos" label="Linux or macOS" default>
|
||
|
||
```bash
|
||
export VARIABLE_NAME='VALUE'
|
||
```
|
||
|
||
</TabItem>
|
||
<TabItem value="windows" label="Windows">
|
||
|
||
```
|
||
set VARIABLE_NAME='VALUE'
|
||
```
|
||
|
||
</TabItem>
|
||
<TabItem value="docker" label="Docker">
|
||
|
||
```bash
|
||
docker run -it --rm \
|
||
-p 7860:7860 \
|
||
-e VARIABLE_NAME='VALUE' \
|
||
langflowai/langflow:latest
|
||
```
|
||
|
||
</TabItem>
|
||
</Tabs>
|
||
|
||
When you start Langflow, it looks for environment variables that you've set in your terminal.
|
||
If it detects a supported environment variable, then it automatically adopts the specified value, subject to [precedence rules](#precedence).
|
||
|
||
### Import environment variables from a .env file {#configure-variables-env-file}
|
||
|
||
1. If Langflow is running, quit Langflow.
|
||
|
||
2. Create a `.env` file, and then open it in your preferred editor.
|
||
|
||
3. Define [Langflow environment variables](#supported-variables) in the `.env` file.
|
||
|
||
<details>
|
||
<summary>Example: .env</summary>
|
||
|
||
```text
|
||
DO_NOT_TRACK=True
|
||
LANGFLOW_AUTO_LOGIN=False
|
||
LANGFLOW_AUTO_SAVING=True
|
||
LANGFLOW_AUTO_SAVING_INTERVAL=1000
|
||
LANGFLOW_BACKEND_ONLY=False
|
||
LANGFLOW_BUNDLE_URLS=["https://github.com/user/repo/commit/hash"]
|
||
LANGFLOW_CACHE_TYPE=async
|
||
LANGFLOW_COMPONENTS_PATH=/path/to/components/
|
||
LANGFLOW_CONFIG_DIR=/path/to/config/
|
||
LANGFLOW_DATABASE_URL=postgresql://user:password@localhost:5432/langflow
|
||
LANGFLOW_DEV=False
|
||
LANGFLOW_FALLBACK_TO_ENV_VAR=False
|
||
LANGFLOW_HEALTH_CHECK_MAX_RETRIES=5
|
||
LANGFLOW_HOST=localhost
|
||
LANGFLOW_LANGCHAIN_CACHE=InMemoryCache
|
||
LANGFLOW_MAX_FILE_SIZE_UPLOAD=10000
|
||
LANGFLOW_MAX_ITEMS_LENGTH=100
|
||
LANGFLOW_MAX_TEXT_LENGTH=1000
|
||
LANGFLOW_LOG_LEVEL=error
|
||
LANGFLOW_OPEN_BROWSER=False
|
||
LANGFLOW_PORT=7860
|
||
LANGFLOW_REMOVE_API_KEYS=False
|
||
LANGFLOW_SAVE_DB_IN_CONFIG_DIR=True
|
||
LANGFLOW_SECRET_KEY=somesecretkey
|
||
LANGFLOW_STORE_ENVIRONMENT_VARIABLES=True
|
||
LANGFLOW_SUPERUSER=adminuser
|
||
LANGFLOW_SUPERUSER_PASSWORD=adminpass
|
||
LANGFLOW_WORKER_TIMEOUT=60000
|
||
LANGFLOW_WORKERS=3
|
||
```
|
||
|
||
For additional examples, see [`.env.example`](https://github.com/langflow-ai/langflow/blob/main/.env.example) in the Langflow repository.
|
||
|
||
</details>
|
||
|
||
4. Save and close `.env`.
|
||
|
||
5. Start Langflow with your `.env` file:
|
||
|
||
<Tabs>
|
||
<TabItem value="local" label="Local" default>
|
||
|
||
```bash
|
||
uv run langflow run --env-file .env
|
||
```
|
||
|
||
</TabItem>
|
||
<TabItem value="docker" label="Docker">
|
||
|
||
```bash
|
||
docker run -it --rm \
|
||
-p 7860:7860 \
|
||
--env-file .env \
|
||
langflowai/langflow:latest
|
||
```
|
||
|
||
</TabItem>
|
||
</Tabs>
|
||
|
||
If your `.env` file isn't in the same directory, provide the path to your `.env` file.
|
||
|
||
On startup, Langflow imports the environment variables from your `.env` file, as well as any others that you set in your terminal, and then adopts their specified values.
|
||
|
||
### Configure environment variables for development
|
||
|
||
The following examples show how to configure Langflow using environment variables in different development scenarios.
|
||
|
||
<Tabs>
|
||
<TabItem value="env" label=".env file" default>
|
||
|
||
The `.env` file is a text file that contains key-value pairs of environment variables.
|
||
|
||
Create or edit a `.env` file in the root directory of your application or Langflow environment, and then add your configuration variables to the file:
|
||
|
||
<details>
|
||
<summary>Example: .env</summary>
|
||
|
||
```text title=".env"
|
||
DO_NOT_TRACK=True
|
||
LANGFLOW_AUTO_LOGIN=False
|
||
LANGFLOW_AUTO_SAVING=True
|
||
LANGFLOW_AUTO_SAVING_INTERVAL=1000
|
||
LANGFLOW_BACKEND_ONLY=False
|
||
LANGFLOW_BUNDLE_URLS=["https://github.com/user/repo/commit/hash"]
|
||
LANGFLOW_CACHE_TYPE=async
|
||
LANGFLOW_COMPONENTS_PATH=/path/to/components/
|
||
LANGFLOW_CONFIG_DIR=/path/to/config/
|
||
LANGFLOW_DATABASE_URL=postgresql://user:password@localhost:5432/langflow
|
||
LANGFLOW_DEV=False
|
||
LANGFLOW_FALLBACK_TO_ENV_VAR=False
|
||
LANGFLOW_HEALTH_CHECK_MAX_RETRIES=5
|
||
LANGFLOW_HOST=localhost
|
||
LANGFLOW_LANGCHAIN_CACHE=InMemoryCache
|
||
LANGFLOW_MAX_FILE_SIZE_UPLOAD=10000
|
||
LANGFLOW_MAX_ITEMS_LENGTH=100
|
||
LANGFLOW_MAX_TEXT_LENGTH=1000
|
||
LANGFLOW_LOG_LEVEL=error
|
||
LANGFLOW_OPEN_BROWSER=False
|
||
LANGFLOW_PORT=7860
|
||
LANGFLOW_REMOVE_API_KEYS=False
|
||
LANGFLOW_SAVE_DB_IN_CONFIG_DIR=True
|
||
LANGFLOW_SECRET_KEY=somesecretkey
|
||
LANGFLOW_STORE_ENVIRONMENT_VARIABLES=True
|
||
LANGFLOW_SUPERUSER=adminuser
|
||
LANGFLOW_SUPERUSER_PASSWORD=adminpass
|
||
LANGFLOW_WORKER_TIMEOUT=60000
|
||
LANGFLOW_WORKERS=3
|
||
```
|
||
|
||
</details>
|
||
|
||
</TabItem>
|
||
<TabItem value="systemd" label="Systemd service">
|
||
|
||
A systemd service configuration file configures Linux system services.
|
||
|
||
To add environment variables, create or edit a service configuration file and add an `override.conf` file. This file allows you to override the default environment variables for the service.
|
||
|
||
<details>
|
||
<summary>Example: override.conf</summary>
|
||
|
||
```ini title="override.conf"
|
||
[Service]
|
||
Environment="DO_NOT_TRACK=true"
|
||
Environment="LANGFLOW_AUTO_LOGIN=false"
|
||
Environment="LANGFLOW_AUTO_SAVING=true"
|
||
Environment="LANGFLOW_AUTO_SAVING_INTERVAL=1000"
|
||
Environment="LANGFLOW_BACKEND_ONLY=false"
|
||
Environment="LANGFLOW_BUNDLE_URLS=[\"https://github.com/user/repo/commit/hash\"]"
|
||
Environment="LANGFLOW_CACHE_TYPE=async"
|
||
Environment="LANGFLOW_COMPONENTS_PATH=/path/to/components/"
|
||
Environment="LANGFLOW_CONFIG_DIR=/path/to/config"
|
||
Environment="LANGFLOW_DATABASE_URL=postgresql://user:password@localhost:5432/langflow"
|
||
Environment="LANGFLOW_DEV=false"
|
||
Environment="LANGFLOW_FALLBACK_TO_ENV_VAR=false"
|
||
Environment="LANGFLOW_HEALTH_CHECK_MAX_RETRIES=5"
|
||
Environment="LANGFLOW_HOST=localhost"
|
||
Environment="LANGFLOW_LANGCHAIN_CACHE=InMemoryCache"
|
||
Environment="LANGFLOW_MAX_FILE_SIZE_UPLOAD=10000"
|
||
Environment="LANGFLOW_MAX_ITEMS_LENGTH=100"
|
||
Environment="LANGFLOW_MAX_TEXT_LENGTH=1000"
|
||
Environment="LANGFLOW_LOG_ENV=container_json"
|
||
Environment="LANGFLOW_LOG_FILE=logs/langflow.log"
|
||
Environment="LANGFLOW_LOG_LEVEL=error"
|
||
Environment="LANGFLOW_OPEN_BROWSER=false"
|
||
Environment="LANGFLOW_PORT=7860"
|
||
Environment="LANGFLOW_REMOVE_API_KEYS=false"
|
||
Environment="LANGFLOW_SAVE_DB_IN_CONFIG_DIR=true"
|
||
Environment="LANGFLOW_SECRET_KEY=somesecretkey"
|
||
Environment="LANGFLOW_STORE_ENVIRONMENT_VARIABLES=true"
|
||
Environment="LANGFLOW_SUPERUSER=adminuser"
|
||
Environment="LANGFLOW_SUPERUSER_PASSWORD=adminpass"
|
||
Environment="LANGFLOW_WORKER_TIMEOUT=60000"
|
||
Environment="LANGFLOW_WORKERS=3"
|
||
```
|
||
|
||
</details>
|
||
|
||
For more information on systemd, see the [Red Hat documentation](https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/using_systemd_unit_files_to_customize_and_optimize_your_system/assembly_working-with-systemd-unit-files_working-with-systemd).
|
||
|
||
</TabItem>
|
||
<TabItem value="vscode" label="VSCode tasks.json">
|
||
|
||
The `tasks.json` file located in `.vscode/tasks.json` is a configuration file for development environments using Visual Studio Code.
|
||
|
||
Create or edit the `.vscode/tasks.json` file in your project root.
|
||
|
||
<details>
|
||
<summary>Example: .vscode/tasks.json</summary>
|
||
|
||
```json title=".vscode/tasks.json"
|
||
{
|
||
"version": "2.0.0",
|
||
"options": {
|
||
"env": {
|
||
"DO_NOT_TRACK": "true",
|
||
"LANGFLOW_AUTO_LOGIN": "false",
|
||
"LANGFLOW_AUTO_SAVING": "true",
|
||
"LANGFLOW_AUTO_SAVING_INTERVAL": "1000",
|
||
"LANGFLOW_BACKEND_ONLY": "false",
|
||
"LANGFLOW_BUNDLE_URLS": "[\"https://github.com/user/repo/commit/hash\"]",
|
||
"LANGFLOW_CACHE_TYPE": "async",
|
||
"LANGFLOW_COMPONENTS_PATH": "D:/path/to/components/",
|
||
"LANGFLOW_CONFIG_DIR": "D:/path/to/config/",
|
||
"LANGFLOW_DATABASE_URL": "postgresql://postgres:password@localhost:5432/langflow",
|
||
"LANGFLOW_DEV": "false",
|
||
"LANGFLOW_FALLBACK_TO_ENV_VAR": "false",
|
||
"LANGFLOW_HEALTH_CHECK_MAX_RETRIES": "5",
|
||
"LANGFLOW_HOST": "localhost",
|
||
"LANGFLOW_LANGCHAIN_CACHE": "InMemoryCache",
|
||
"LANGFLOW_MAX_FILE_SIZE_UPLOAD": "10000",
|
||
"LANGFLOW_MAX_ITEMS_LENGTH": "100",
|
||
"LANGFLOW_MAX_TEXT_LENGTH": "1000",
|
||
"LANGFLOW_LOG_ENV": "container_csv",
|
||
"LANGFLOW_LOG_FILE": "langflow.log",
|
||
"LANGFLOW_LOG_LEVEL": "error",
|
||
"LANGFLOW_OPEN_BROWSER": "false",
|
||
"LANGFLOW_PORT": "7860",
|
||
"LANGFLOW_REMOVE_API_KEYS": "true",
|
||
"LANGFLOW_SAVE_DB_IN_CONFIG_DIR": "false",
|
||
"LANGFLOW_SECRET_KEY": "somesecretkey",
|
||
"LANGFLOW_STORE_ENVIRONMENT_VARIABLES": "true",
|
||
"LANGFLOW_SUPERUSER": "adminuser",
|
||
"LANGFLOW_SUPERUSER_PASSWORD": "adminpass",
|
||
"LANGFLOW_WORKER_TIMEOUT": "60000",
|
||
"LANGFLOW_WORKERS": "3"
|
||
}
|
||
},
|
||
"tasks": [
|
||
{
|
||
"label": "langflow backend",
|
||
"type": "shell",
|
||
"command": ". ./langflownightly/Scripts/activate && langflow run",
|
||
"isBackground": true,
|
||
"problemMatcher": []
|
||
}
|
||
]
|
||
}
|
||
```
|
||
|
||
</details>
|
||
|
||
To run Langflow using the above VSCode `tasks.json` file, in the VSCode command palette, select **Tasks: Run Task** > **langflow backend**.
|
||
|
||
</TabItem>
|
||
</Tabs>
|
||
|
||
## Set environment variables for Langflow Desktop
|
||
|
||
Environment variables set in your terminal aren't automatically available to GUI-based applications like Langflow Desktop when you launch them from the Windows or macOS GUI.
|
||
|
||
For Windows, this means any GUI-based app launched from the Start menu, desktop shortcuts, or Windows Explorer.
|
||
|
||
For macOS, this means any GUI-based app launched from Finder, Spotlight, Launchpad, or the Dock.
|
||
|
||
To set environment variables for Langflow Desktop, you need to use specific commands or files, depending on your OS.
|
||
|
||
<Tabs>
|
||
<TabItem value="macos" label="macOS" default>
|
||
|
||
Langflow Desktop for macOS cannot automatically use variables set in your terminal, such as those in`.zshrc` or `.bash_profile`, when launched from the macOS GUI.
|
||
|
||
To make environment variables available to GUI apps on macOS, you need to use `launchctl` with a `plist` file:
|
||
|
||
1. Create the `LaunchAgents` directory if it doesn't exist:
|
||
|
||
```bash
|
||
mkdir -p ~/Library/LaunchAgents
|
||
```
|
||
|
||
2. In the `LaunchAgents` directory, create a `.plist` file called `dev.langflow.env`.
|
||
|
||
3. Add the following content to `dev.langflow.env.plist`, and then add, change, or remove Langflow environment variables as needed for your configuration.
|
||
|
||
This example sets multiple environmental variables for all GUI apps launched from the macOS GUI.
|
||
|
||
```xml
|
||
<?xml version="1.0" encoding="UTF-8"?>
|
||
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
|
||
<plist version="1.0">
|
||
<dict>
|
||
<key>Label</key>
|
||
<string>dev.langflow.env</string>
|
||
<key>ProgramArguments</key>
|
||
<array>
|
||
<string>/bin/sh</string>
|
||
<string>-c</string>
|
||
<string>
|
||
launchctl setenv LANGFLOW_CONFIG_DIR /Users/your_user/custom/config ;
|
||
launchctl setenv LANGFLOW_PORT 7860 ;
|
||
launchctl setenv LANGFLOW_HOST localhost ;
|
||
launchctl setenv ARIZE_API_KEY ak-...
|
||
</string>
|
||
</array>
|
||
<key>RunAtLoad</key>
|
||
<true/>
|
||
</dict>
|
||
</plist>
|
||
```
|
||
4. Load the file with `launchctl`:
|
||
|
||
```bash
|
||
launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/dev.langflow.env.plist
|
||
```
|
||
|
||
</TabItem>
|
||
<TabItem value="windows1" label="Window System Properties">
|
||
|
||
Langflow Desktop for Windows cannot automatically use variables set in your terminal, such as those defined with `set` in `cmd` or `$env:VAR=...` in PowerShell, when launched from the Windows GUI.
|
||
|
||
To make environment variables available to the Langflow Desktop app, you must set them at the user or system level using the **System Properties** interface or the Terminal.
|
||
|
||
To set environment variables using the System Properties interface, do the following:
|
||
|
||
1. Press <kbd>Win + R</kbd>, enter `SystemPropertiesAdvanced`, and then press <kbd>Enter</kbd>.
|
||
2. Click **Environment Variables**.
|
||
3. Under **User variables**, click **New**.
|
||
|
||
:::tip
|
||
To apply the setting to all users, select **System variables**.
|
||
:::
|
||
|
||
4. Enter the name of the Langflow variable you want to set, such as `LANGFLOW_CONFIG_DIR`, and the desired value, such as `C:\Users\your_user\.langflow_config`.
|
||
5. Click **OK** to save the variable.
|
||
6. Repeat until you have set all necessary Langflow environment variables.
|
||
7. Launch or restart Langflow Desktop to apply the environment variables.
|
||
|
||
</TabItem>
|
||
<TabItem value="windows2" label="Powershell">
|
||
|
||
To define environment variables for Windows using PowerShell, do the following:
|
||
|
||
1. Enter the name of the Langflow variable you want to set, such as `LANGFLOW_CONFIG_DIR`, and the desired value, such as `C:\Users\your_user\.langflow_config`.
|
||
|
||
To set an environment variable for the current user:
|
||
```powershell
|
||
[System.Environment]::SetEnvironmentVariable("LANGFLOW_CONFIG_DIR", "C:\Users\your_user\.langflow_config", "User")
|
||
```
|
||
|
||
To set an environment variable for all users (you must have Administrator priveleges):
|
||
```powershell
|
||
[System.Environment]::SetEnvironmentVariable("LANGFLOW_CONFIG_DIR", "C:\Langflow\Config", "Machine")
|
||
```
|
||
|
||
2. Repeat until you have set all necessary Langflow environment variables.
|
||
3. Launch or restart Langflow Desktop to apply the environment variables.
|
||
|
||
</TabItem>
|
||
</Tabs>
|
||
|
||
## Supported environment variables {#supported-variables}
|
||
|
||
The following sections provide information about specific Langflow environment variables.
|
||
|
||
### Authentication and security
|
||
|
||
See [API keys and authentication](/api-keys-and-authentication).
|
||
|
||
### Global variables
|
||
|
||
For information about the relationship between Langflow global variables and environment variables, as well as environment variables that control handling of global variables, see [Global variables](/configuration-global-variables).
|
||
|
||
### Logs {#logging}
|
||
|
||
See [Configure log options](/logging#log-storage).
|
||
|
||
### MCP servers {#mcp}
|
||
|
||
See [Use Langflow as an MCP server](/mcp-server).
|
||
|
||
### Monitoring and metrics
|
||
|
||
For environment variables for specific monitoring service providers, see the Langflow monitoring integration guides, such as [Langfuse](/integrations-langfuse) and [Best practices for Langflow on Kubernetes](/deployment-prod-best-practices).
|
||
|
||
### Server
|
||
|
||
The following environment variables set base Langflow server configuration, such as where the server is hosted, required files for SSL encryption, and the deployment type (frontend and backend, backend-only, development mode).
|
||
|
||
| Variable | Format | Default | Description |
|
||
|----------|--------|---------|-------------|
|
||
| `LANGFLOW_HOST` | String | `localhost` | The host on which the Langflow server will run. |
|
||
| `LANGFLOW_PORT` | Integer | `7860` | The port on which the Langflow server runs. The server automatically selects a free port if the specified port is in use. |
|
||
| `LANGFLOW_BACKEND_ONLY` | Boolean | `False` | Run only the Langflow backend service (no frontend). |
|
||
| `LANGFLOW_DEV` | Boolean | `False` | Whether to run Langflow in development mode (may contain bugs). |
|
||
| `LANGFLOW_OPEN_BROWSER` | Boolean | `False` | Open the system web browser on startup. |
|
||
| `LANGFLOW_HEALTH_CHECK_MAX_RETRIES` | Integer | `5` | Set the maximum number of retries for Langflow's server status health checks. |
|
||
| `LANGFLOW_WORKERS` | Integer | `1` | Number of worker processes. |
|
||
| `LANGFLOW_WORKER_TIMEOUT` | Integer | `300` | Worker timeout in seconds. |
|
||
| `LANGFLOW_GUNICORN_PRELOAD` | Boolean | `False` | **Experimental.** When `true`, enables Gunicorn `preload_app` (non-Windows): the app is loaded in the master process before worker processes fork. Can reduce per-worker startup cost; behavior and compatibility may change. |
|
||
| `LANGFLOW_JOB_QUEUE_TYPE` | String | `asyncio` | Job queue backend. Use `redis` to share queue events across workers. |
|
||
| `LANGFLOW_REDIS_QUEUE_DB` | Integer | `1` | Redis database index used by the Redis job queue backend. |
|
||
| `LANGFLOW_SSL_CERT_FILE` | String | Not set | Path to the SSL certificate file for enabling HTTPS on the Langflow web server. This is separate from [database SSL connections](/configuration-custom-database#connect-langflow-to-a-local-postgresql-database). |
|
||
| `LANGFLOW_SSL_KEY_FILE` | String | Not set | Path to the SSL key file for enabling HTTPS on the Langflow web server. This is separate from [database SSL connections](/configuration-custom-database#connect-langflow-to-a-local-postgresql-database). |
|
||
| `LANGFLOW_DEACTIVATE_TRACING` | Boolean | `False` | Deactivate tracing functionality. |
|
||
| `LANGFLOW_CELERY_ENABLED` | Boolean | `False` | Enable Celery for distributed task processing. |
|
||
| `LANGFLOW_ALEMBIC_LOG_TO_STDOUT` | Boolean | `False` | Whether to log Alembic database migration output to stdout instead of a log file. If `true`, Alembic logs to `stdout` and the default log file is ignored. |
|
||
|
||
### High-load and multi-worker environments
|
||
|
||
For high-concurrency deployments (such as when increasing `LANGFLOW_WORKERS`), consider the following best practices:
|
||
- **Enable Gunicorn preload (experimental):**
|
||
Set `LANGFLOW_GUNICORN_PRELOAD=true` to enable Gunicorn’s `preload_app` mode, which can reduce per-worker startup overhead (non-Windows only).
|
||
- **Use Redis-backed job queue:**
|
||
Set `LANGFLOW_JOB_QUEUE_TYPE=redis` to share queue events across workers.
|
||
**Note:** Always configure a dedicated Redis database for the job queue, separate from the cache database.
|
||
- **Disable tracing:**
|
||
Set `LANGFLOW_DEACTIVATE_TRACING=True` to turn off tracing, which may cause concurrency bottlenecks under high load or in multi-worker environments.
|
||
- **Use PostgreSQL instead of SQLite:**
|
||
SQLite can experience database locks and deadlocks with concurrent, write-heavy usage. For production or multi-worker environments, configure Langflow to use PostgreSQL by setting the `LANGFLOW_DATABASE_URL` environment variable (see [Memory management options](/memory#configure-external-memory)). This is strongly recommended to avoid operational issues.
|
||
|
||
For more information about deploying Langflow servers, see [Langflow deployment overview](/deployment-overview).
|
||
|
||
### Storage
|
||
|
||
For file storage environment variables, see [File storage environment variables](/concepts-file-management#file-storage-environment-variables).
|
||
|
||
For database environment variables, including PostgreSQL configuration, see [Memory management options](/memory#configure-external-memory).
|
||
|
||
### Telemetry
|
||
|
||
See [Telemetry](/contributing-telemetry).
|
||
|
||
### Visual editor and Playground behavior
|
||
|
||
| Variable | Format | Default | Description |
|
||
|----------|--------|---------|-------------|
|
||
| `LANGFLOW_AUTO_SAVING` | Boolean | `True` | Whether to automatically save flows. |
|
||
| `LANGFLOW_AUTO_SAVING_INTERVAL` | Integer | `1000` | Set the auto-save interval in milliseconds if `LANGFLOW_AUTO_SAVING=True`. |
|
||
| `LANGFLOW_BUNDLE_URLS` | List[String] | `[]` | A list of URLs from which to load custom bundles. Supports GitHub URLs. If `LANGFLOW_AUTO_LOGIN=True`, flows from these bundles are loaded into the database. |
|
||
| `LANGFLOW_COMPONENTS_PATH` | String | Not set | Path to a directory containing custom components. Typically used if you have local custom components or you are building a Docker image with custom components. |
|
||
| `LANGFLOW_LOAD_FLOWS_PATH` | String | Not set | Path to a directory containing flow JSON files to be loaded on startup. Typically used when creating a Docker image with prepackaged flows. Requires `LANGFLOW_AUTO_LOGIN=True`. |
|
||
| `LANGFLOW_CREATE_STARTER_PROJECTS` | Boolean | `True` | Whether to create templates during initialization. If `false`, Langflow doesn't create templates, and `LANGFLOW_UPDATE_STARTER_PROJECTS` is treated as `false`. |
|
||
| `LANGFLOW_UPDATE_STARTER_PROJECTS` | Boolean | `True` | Whether to update templates with the latest component versions when initializing after an upgrade. |
|
||
| `LANGFLOW_LAZY_LOAD_COMPONENTS` | Boolean | `False` | If `true`, Langflow only partially loads components at startup and fully loads them on demand. This significantly reduces startup time but can cause a slight delay when a component is first used. |
|
||
| `LANGFLOW_EVENT_DELIVERY` | String | `streaming` | How to deliver build events to the frontend: `polling`, `streaming` or `direct`. |
|
||
| `LANGFLOW_FRONTEND_PATH` | String | `./frontend` | Path to the frontend directory containing build files. For development purposes only when you need to serve specific frontend code. |
|
||
| `LANGFLOW_MAX_ITEMS_LENGTH` | Integer | `100` | Maximum number of items to store and display in the visual editor. Lists longer than this will be truncated when displayed in the visual editor. Doesn't affect outputs or data passed between components. |
|
||
| `LANGFLOW_MAX_TEXT_LENGTH` | Integer | `1000` | Maximum number of characters to store and display in the visual editor. Responses longer than this will be truncated when displayed in the visual editor. Doesn't truncate outputs or responses passed between components. |
|
||
| `LANGFLOW_MAX_TRANSACTIONS_TO_KEEP` | Integer | `3000` | Maximum number of flow transaction events to keep in the database. |
|
||
| `LANGFLOW_MAX_VERTEX_BUILDS_TO_KEEP` | Integer | `3000` | Maximum number of vertex builds to keep in the database. Relates to [Playground](/concepts-playground) functionality. |
|
||
| `LANGFLOW_MAX_VERTEX_BUILDS_PER_VERTEX` | Integer | `2` | Maximum number of builds to keep per vertex. Older builds are deleted. Relates to [Playground](/concepts-playground) functionality. |
|
||
| `LANGFLOW_PUBLIC_FLOW_CLEANUP_INTERVAL` | Integer | `3600` | The interval in seconds at which data for [shared Playground](/concepts-playground#share-a-flows-playground) flows are cleaned up. Default: 3600 seconds (1 hour). Minimum: 600 seconds (10 minutes). |
|
||
| `LANGFLOW_PUBLIC_FLOW_EXPIRATION` | Integer | `86400` | The time in seconds after which a [shared Playground](/concepts-playground#share-a-flows-playground) flow is considered expired and eligible for cleanup. Default: 86400 seconds (24 hours). Minimum: 600 seconds (10 minutes). |
|