Connect to an external Redis database

LangSmith uses Redis to back our queuing/caching operations. By default, LangSmith Self-Hosted will use an internal Redis instance. However, you can configure LangSmith to use an external Redis instance. By configuring an external Redis instance, you can more easily manage backups, scaling, and other operational tasks for your Redis instance.

Requirements

• A provisioned Redis instance that your LangSmith instance will have network access to. We recommend using a managed Redis service like:

  • Amazon ElastiCache
  • Google Cloud Memorystore
  • Azure Cache for Redis

• Note: We only officially support Redis versions >= 5.

• We support both Standalone and Redis Cluster. See the appropriate sections for deployment instructions.

• We support no authentication, password, and IAM/Workload Identity authentication.

• By default, we recommend an instance with at least 2 vCPUs and 8GB of memory. However, the actual requirements will depend on your tracing workload. We recommend monitoring your Redis instance and scaling up as needed.

Standalone Redis

Connection String

You will need to assemble the connection string for your Redis instance. This connection string should include the following information:

• Host
• Database
• Port
• URL params

This will take the form of:

"redis://host:port/db?<url_params>"

An example connection string might look like:

"redis://langsmith-redis:6379/0"

Note: If your Standalone Redis requires authentication or TLS, include these directly in the connection URL:

• Use rediss:// when TLS is enabled on your Redis server.
• Provide the password in the connection string.

For example:

rediss://langsmith-redis:6380/0?password=foo

For IAM authentication, use the identity as the username (no password):

rediss://<iam-identity>@host:6380

Configuration

With your connection string in hand, you can configure your LangSmith instance to use an external Redis instance. You can do this by modifying the values file for your LangSmith Helm Chart installation or the .env file for your Docker installation.

Helm

redis:
  external:
    enabled: true
    connectionUrl: "Your connection url"

You can also store the connection URL in an existing Kubernetes Secret and reference it in your Helm values.

Helm (using an existing Secret)

redis:
  external:
    enabled: true
    # Name of an existing Secret that contains the connection URL
    existingSecretName: "my-redis-secret"
    # Key in the Secret that stores the connection URL (default shown)
    connectionUrlSecretKey: "connection_url"

Once configured, you should be able to reinstall your LangSmith instance. If everything is configured correctly, your LangSmith instance should now be using your external Redis instance.

Redis Cluster

As of LangSmith helm version 0.12.25, we officially support Redis Cluster.

Host Names

When using Redis Cluster, provide a list of node hostnames and ports. Each node URI must be in the form:

redis://hostname:port

For example:

redis://redis-node-0:6379
redis://redis-node-1:6379
redis://redis-node-2:6379

Do not include a password in these URIs, and do not use rediss here. For Redis Cluster:

• Provide the password separately via redis.external.cluster.password or through a Secret using passwordSecretKey.
• Enable TLS separately with redis.external.cluster.tlsEnabled: true.

Configuration

When connecting to an external Redis Cluster, configure the Helm values under redis.external.cluster. You can either:

• Provide node URIs and (optionally) a password directly in values.yaml.
• Or reference an existing Kubernetes Secret containing node URIs and password.

Helm (inline values)

redis:
  external:
    enabled: true
    cluster:
      enabled: true
      # List of cluster node URIs. Format: redis://host:port
      nodeUris:
        - "redis://redis-node-0:6379"
        - "redis://redis-node-1:6379"
        - "redis://redis-node-2:6379"
      # Optional. If your cluster requires auth, set a password or use a Secret (recommended).
      password: "your_redis_password"
      # Enable if your cluster uses TLS.
      tlsEnabled: true

If using an existing Secret, it should contain:

Kubernetes Secret

apiVersion: v1
kind: Secret
metadata:
  name: my-redis-cluster-secret
type: Opaque
stringData:
  # JSON array of node URIs (as a string)
  redis_cluster_node_uris: '["redis://redis-node-0:6379","redis://redis-node-1:6379","redis://redis-node-2:6379"]'
  # Optional if your cluster requires a password
  redis_cluster_password: "your_redis_password"

TLS with Redis

Use this section to configure TLS for Redis connections. For mounting internal/public CAs so LangSmith trusts your Redis server certificate, see Configure custom TLS certificates.

Server TLS (one-way)

To validate the Redis server certificate:

• Provide a CA bundle using config.customCa.secretName and config.customCa.secretKey.
• For Standalone Redis, use rediss:// in the connection URL.
• For Redis Cluster, set redis.external.cluster.tlsEnabled: true.

Mount a custom CA only when your Redis server uses an internal or private CA. Publicly trusted CAs do not require this configuration.

Helm (Standalone - server TLS)

config:
  customCa:
    secretName: "langsmith-custom-ca"  # Secret containing your CA bundle
    secretKey: "ca.crt"    # Key in the Secret with the CA bundle
redis:
  external:
    enabled: true
    # Use rediss:// and include password if required by your server
    connectionUrl: "rediss://host:6380/0?password=<PASSWORD>"

Mutual TLS with Client Auth (mTLS)

As of LangSmith helm chart version 0.12.29, we support mTLS for Redis clients. For server-side authentication in mTLS, use the Server TLS steps (custom CA) in addition to the following client certificate configuration.

If your Redis server requires client certificate authentication:

• Provide a Secret with your client certificate and key.
• Reference it via redis.external.clientCert.secretName and specify the keys with certSecretKey and keySecretKey.
• For Standalone Redis, keep using rediss:// in the connection URL.
• For Redis Cluster, set redis.external.cluster.tlsEnabled: true.

Helm (client Auth)

redis:
  external:
    enabled: true
    clientCert:
      secretName: "redis-mtls-secret"
      certSecretKey: "tls.crt"
      keySecretKey: "tls.key"
    # Standalone example:
    # connectionUrl: "rediss://host:6380/0?password=<PASSWORD>"
    # Or, for Cluster:
    cluster:
      enabled: true
      tlsEnabled: true
      nodeUris:
        - "redis://redis-node-0:6379"
        - "redis://redis-node-1:6379"
        - "redis://redis-node-2:6379"
      password: "<PASSWORD>"

Pod security context for certificate volumes

The certificate volumes mounted for mTLS are protected by file access restrictions. To ensure all LangSmith pods can read the certificate files, you must set fsGroup: 1000 in the pod security context.

You can configure this in one of two ways:

Option 1: Use commonPodSecurityContext

Set the fsGroup at the top level to apply it to all pods:

commonPodSecurityContext:
  fsGroup: 1000

Option 2: Add to individual pod security contexts

If you need more granular control, add the fsGroup to each pod’s security context individually. See the mtls configuration example for a complete reference.

IAM Authentication

As of LangSmith helm chart version 0.12.34, we support IAM authentication for Redis. This allows you to use cloud provider workload identity instead of static passwords.

IAM authentication is supported for both standalone Redis and Redis Cluster configurations. However, not all cloud providers support IAM authentication for all Redis offerings. Check your cloud provider’s documentation to verify IAM support for your specific Redis setup (e.g., GCP only supports IAM for Memorystore Cluster, not standalone Memorystore).

Supported providers

Provider	Redis Service	Documentation
AWS	ElastiCache for Redis	IAM authentication
GCP	Memorystore for Redis	IAM authentication
Azure	Azure Cache for Redis	Microsoft Entra authentication

Prerequisites

1. Configure workload identity in your Kubernetes cluster. See your cloud provider’s documentation:

   • AWS IRSA or EKS Pod Identity
   • GCP Workload Identity
   • Azure Workload Identity

2. Enable IAM authentication on your Redis instance and grant access to your workload identity. Refer to your cloud provider’s documentation linked above.

3. Annotate your Kubernetes ServiceAccounts and Deployments/Jobs with the workload identity binding per your cloud provider’s requirements.

Configuration

To enable IAM authentication, set the iamAuthProvider field and use an IAM-compatible connection string (with identity as username, no password):

Helm

redis:
  external:
    enabled: true
    existingSecretName: "redis-secret"
    iamAuthProvider: "azure"  # or "gcp" or "aws"

Kubernetes Secret

apiVersion: v1
kind: Secret
metadata:
  name: redis-secret
type: Opaque
stringData:
  # IAM connection URL - identity as username, no password
  connection_url: "rediss://<identity>@<host>:6380"

Redis Cluster with IAM Authentication

For Redis Cluster with IAM authentication, configure both the cluster settings and IAM provider:

Helm

redis:
  external:
    enabled: true
    existingSecretName: "redis-cluster-secret"
    iamAuthProvider: "gcp"  # or "aws" or "azure"
    cluster:
      enabled: true
      nodeUrisSecretKey: "redis_cluster_node_uris"
      tlsEnabled: true

Required annotations

You must apply the ServiceAccount annotations and pod labels required by your cloud provider’s workload identity to all LangSmith components that connect to Redis. This includes:

Deployments: backend, queue, platformBackend, hostBackend

Example for the backend service (repeat for other services listed above):

AWS

backend:
  serviceAccount:
    annotations:
      eks.amazonaws.com/role-arn: "arn:aws:iam::<account-id>:role/<role-name>"
...

See the Helm values reference for the full list of configurable services and their annotation/label options.

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