Environment variables

The LangGraph Server supports specific environment variables for configuring a deployment.

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BG_JOB_ISOLATED_LOOPS

Set BG_JOB_ISOLATED_LOOPS to True to execute background runs in an isolated event loop separate from the serving API event loop. This environment variable should be set to True if the implementation of a graph/node contains synchronous code. In this situation, the synchronous code will block the serving API event loop, which may cause the API to be unavailable. A symptom of an unavailable API is continuous application restarts due to failing health checks. Defaults to False.

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BG_JOB_SHUTDOWN_GRACE_PERIOD_SECS

Specifies, in seconds, how long the server will wait for background jobs to finish after the queue receives a shutdown signal. After this period, the server will force termination. Defaults to 180 seconds. Set this to ensure jobs have enough time to complete cleanly during shutdown. Added in langgraph-api==0.2.16.

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BG_JOB_TIMEOUT_SECS

The timeout of a background run can be increased. However, the infrastructure for a Cloud SaaS deployment enforces a 1 hour timeout limit for API requests. This means the connection between client and server will timeout after 1 hour. This is not configurable. A background run can execute for longer than 1 hour, but a client must reconnect to the server (e.g. join stream via POST /threads/{thread_id}/runs/{run_id}/stream) to retrieve output from the run if the run is taking longer than 1 hour. Defaults to 3600.

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DD_API_KEY

Specify DD_API_KEY (your Datadog API Key) to automatically enable Datadog tracing for the deployment. Specify other DD_* environment variables to configure the tracing instrumentation. If DD_API_KEY is specified, the application process is wrapped in the ddtrace-run command. Other DD_* environment variables (e.g. DD_SITE, DD_ENV, DD_SERVICE, DD_TRACE_ENABLED) are typically needed to properly configure the tracing instrumentation. See DD_* environment variables for more details.

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LANGCHAIN_TRACING_SAMPLING_RATE

Sampling rate for traces sent to LangSmith. Valid values: Any float between 0 and 1. See LangSmith documentation for more details.

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LANGGRAPH_AUTH_TYPE

Type of authentication for the LangGraph Server deployment. Valid values: langsmith, noop. For deployments to LangGraph Platform, this environment variable is set automatically. For local development or deployments where authentication is handled externally (e.g. self-hosted), set this environment variable to noop.

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LANGGRAPH_POSTGRES_POOL_MAX_SIZE

Beginning with langgraph-api version 0.2.12, the maximum size of the Postgres connection pool (per replica) can be controlled using the LANGGRAPH_POSTGRES_POOL_MAX_SIZE environment variable. By setting this variable, you can determine the upper bound on the number of simultaneous connections the server will establish with the Postgres database. For example, if a deployment is scaled up to 10 replicas and LANGGRAPH_POSTGRES_POOL_MAX_SIZE is configured to 150, then up to 1500 connections to Postgres can be established. This is particularly useful for deployments where database resources are limited (or more available) or where you need to tune connection behavior for performance or scaling reasons. Defaults to 150 connections.

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LANGSMITH_RUNS_ENDPOINTS

For deployments with self-hosted LangSmith only. Set this environment variable to have a deployment send traces to a self-hosted LangSmith instance. The value of LANGSMITH_RUNS_ENDPOINTS is a JSON string: {"<SELF_HOSTED_LANGSMITH_HOSTNAME>":"<LANGSMITH_API_KEY>"}. SELF_HOSTED_LANGSMITH_HOSTNAME is the hostname of the self-hosted LangSmith instance. It must be accessible to the deployment. LANGSMITH_API_KEY is a LangSmith API generated from the self-hosted LangSmith instance.

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LANGSMITH_TRACING

Set LANGSMITH_TRACING to false to disable tracing to LangSmith. Defaults to true.

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LOG_COLOR

This is mainly relevant in the context of using the dev server via the langgraph dev command. Set LOG_COLOR to true to enable ANSI-colored console output when using the default console renderer. Disabling color output by setting this variable to false produces monochrome logs. Defaults to true.

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LOG_LEVEL

Configure log level. Defaults to INFO.

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LOG_JSON

Set LOG_JSON to true to render all log messages as JSON objects using the configured JSONRenderer. This produces structured logs that can be easily parsed or ingested by log management systems. Defaults to false.

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MOUNT_PREFIX

Set MOUNT_PREFIX to serve the LangGraph Server under a specific path prefix. This is useful for deployments where the server is behind a reverse proxy or load balancer that requires a specific path prefix. For example, if the server is to be served under https://example.com/langgraph, set MOUNT_PREFIX to /langgraph.

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N_JOBS_PER_WORKER

Number of jobs per worker for the LangGraph Server task queue. Defaults to 10.

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POSTGRES_URI_CUSTOM

Specify POSTGRES_URI_CUSTOM to use a custom Postgres instance. The value of POSTGRES_URI_CUSTOM must be a valid Postgres connection URI. Postgres:

• Version 15.8 or higher.
• An initial database must be present and the connection URI must reference the database.

Control Plane Functionality:

• If POSTGRES_URI_CUSTOM is specified, the LangGraph Control Plane will not provision a database for the server.
• If POSTGRES_URI_CUSTOM is removed, the LangGraph Control Plane will not provision a database for the server and will not delete the externally managed Postgres instance.
• If POSTGRES_URI_CUSTOM is removed, deployment of the revision will not succeed. Once POSTGRES_URI_CUSTOM is specified, it must always be set for the lifecycle of the deployment.
• If the deployment is deleted, the LangGraph Control Plane will not delete the externally managed Postgres instance.
• The value of POSTGRES_URI_CUSTOM can be updated. For example, a password in the URI can be updated.

Database Connectivity:

• The custom Postgres instance must be accessible by the LangGraph Server. The user is responsible for ensuring connectivity.

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REDIS_CLUSTER

Set REDIS_CLUSTER to True to enable Redis Cluster mode. When enabled, the system will connect to Redis using cluster mode. This is useful when connecting to a Redis Cluster deployment. Defaults to False.

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REDIS_KEY_PREFIX

Specify a prefix for Redis keys. This allows multiple LangGraph Server instances to share the same Redis instance by using different key prefixes. Defaults to ''.

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REDIS_URI_CUSTOM

Specify REDIS_URI_CUSTOM to use a custom Redis instance. The value of REDIS_URI_CUSTOM must be a valid Redis connection URI.

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RESUMABLE_STREAM_TTL_SECONDS

Time-to-live in seconds for resumable stream data in Redis. When a run is created and the output is streamed, the stream can be configured to be resumable (e.g. stream_resumable=True). If a stream is resumable, output from the stream is temporarily stored in Redis. The TTL for this data can be configured by setting RESUMABLE_STREAM_TTL_SECONDS. See the Python and JS/TS SDKs for more details on how to implement resumable streams. Defaults to 120 seconds.