title	Use session pools in Azure Container Apps
description	Learn to use and manage session pools in Azure Container Apps.
services	container-apps
author	craigshoemaker
ms.service	azure-container-apps
ms.topic	how-to
ms.date	04/07/2025
ms.author	cshoe

Use session pools in Azure Container Apps

Session pools provide subsecond session allocation times and manage the lifecycle of each session.

Common concepts for both pools

The process for creating a pool is slightly different depending on whether you're creating a code interpreter session pool or a custom container pool. The following concepts apply to both.

To create session pools using the Azure CLI, ensure you have the latest versions of the Azure CLI and the Azure Container Apps extension:

# Upgrade the Azure CLI
az upgrade

# Install or upgrade the Azure Container Apps extension
az extension add --name containerapp --upgrade --allow-preview true -y

Common session pool commands include:

az containerapp sessionpool create
az containerapp sessionpool show
az containerapp sessionpool list
az containerapp sessionpool update
az containerapp sessionpool delete

Use --help with any command to see available arguments and supported values.

To check the status of a session pool, use the az containerapp sessionpool show command:

az containerapp sessionpool show \
    --name <SESSION_POOL_NAME> \
    --resource-group <RESOURCE_GROUP> \
    --query "properties.poolManagementEndpoint" \
    --output tsv

When you create or update a pool, you can set a maximum number of concurrent sessions, an idle cooldown period, and whether outbound network traffic is allowed for sessions.

Important

If you enable egress, code running in the session can access the internet. Use caution when the code is untrusted because it can be used to perform malicious activities such as denial-of-service attacks.

Important

If the session is used to run untrusted code, don't include information or data that you don't want the untrusted code to access. Assume the code is malicious and has full access to the container, including its environment variables, secrets, and files.

Configure a pool

Use az containerapp sessionpool create --help to see the latest CLI arguments for session pool configuration. This section focuses on advanced configuration options that apply across API versions.

Session lifecycle configuration

When you create or update a session pool, you can configure how sessions are terminated by setting properties.dynamicPoolConfiguration.lifecycleConfiguration. Starting with API version 2025-01-01, choose one of two lifecycle types.

For the full API specification, see the SessionPools API spec.

Timed (default)

With the Timed lifecycle, a session is deleted after a period of inactivity. Any request sent to a session resets the cooldown timer, extending the session's time-to-live by cooldownPeriodInSeconds.

Note

Timed is supported for all session pool types and works the same as executionType: Timed in earlier API versions.

{
  "dynamicPoolConfiguration": {
    "lifecycleConfiguration": {
      "cooldownPeriodInSeconds": 600,
      "lifecycleType": "Timed"
    }
  }
}

Property	Description
`cooldownPeriodInSeconds`	The session is deleted when there are no requests for this duration.
`maxAlivePeriodInSeconds`	Not supported for `Timed` lifecycle.

Management endpoint

Important

The session identifier is sensitive information which requires a secure process as you create and manage its value. To protect this value, your application must ensure each user or tenant only has access to their own sessions.

Failure to secure access to sessions could result in misuse or unauthorized access to data stored in your users' sessions. For more information, see Session identifiers

All requests to the pool management endpoint must include an Authorization header with a bearer token. To learn how to authenticate with the pool management API, see Authentication.

Each API request must also include the query string parameter identifier with the session ID. This unique session ID enables your application to interact with specific sessions. To learn more about session identifiers, see Session identifiers.

Image caching

When a session pool is created or updated, Azure Container Apps caches the container image in the pool. This caching helps speed up the process of creating new sessions.

Any changes to the image aren't automatically reflected in the sessions. To update the image, update the session pool with a new image tag. Use a unique tag for each image update to ensure that the new image is pulled.

Code interpreter session pool

Azure CLI

Use the az containerapps sessionpool create command to create the pool. The following example creates a Python code interpreter session pool named my-session-pool. Make sure to replace <RESOURCE_GROUP> with your resource group name before you run the command.

az containerapp sessionpool create \
    --name my-session-pool \
    --resource-group <RESOURCE_GROUP> \
    --location westus2 \
    --container-type PythonLTS \
    --max-sessions 100 \
    --cooldown-period 300 \
    --network-status EgressDisabled

You can define the following settings when you create a session pool:

Setting	Description
`--container-type`	The type of code interpreter to use. Supported values include `PythonLTS`, `NodeLTS`, `Shell`, and `CustomContainer`.
`--max-sessions`	The maximum number of allocated sessions allowed concurrently. The maximum value is `600`.
`--cooldown-period`	The number of allowed idle seconds before termination. The idle period is reset each time the session's API is called. The allowed range is between `300` and `3600`.
`--network-status`	Specifies whether outbound network traffic is allowed from the session. Valid values are `EgressDisabled` (default) and `EgressEnabled`.

Azure portal

Sign in to the Azure portal.
In the search bar at the top of the portal, search for and select Container Apps Session Pools.
Select Create.

In the Basics tab, enter the following values:

Setting	Action
Subscription	Select your Azure subscription.
Resource group	Select an existing resource group or select Create new.
Session pool name	Enter a name for your session pool.
Region	Select a supported region.
Pool type	Select Code interpreter.
Container type	Select PythonLTS, NodeLTS, or Shell.

In the Configuration section, enter the following values:

Setting	Action
Maximum sessions	Enter the maximum number of concurrent sessions. The maximum value is `600`.
Cooldown period (seconds)	Enter the number of idle seconds before a session is terminated. The allowed range is `300` to `3600`.
Outbound network	Select Disabled to block outbound traffic, or Enabled to allow it.

[!IMPORTANT] If you enable outbound network access, code running in the session can access the internet. Use caution when the code is untrusted.

Select Review + create.
After validation passes, select Create.

Code interpreter management endpoint

To use code interpreter sessions with LLM framework integrations or by calling the management API endpoints directly, you need the pool's management API endpoint.

The endpoint is in the format https://<REGION>.dynamicsessions.io/subscriptions/<SUBSCRIPTION_ID>/resourceGroups/<RESOURCE_GROUP>/sessionPools/<SESSION_POOL_NAME>.

To retrieve the management API endpoint for a session pool, see the common section above for an example command.

The following endpoints are available for managing sessions in a pool:

Endpoint path	Method	Description
`code/execute`	`POST`	Execute code in a session.
`files/upload`	`POST`	Upload a file to a session.
`files/content/{filename}`	`GET`	Download a file from a session.
`files`	`GET`	List the files in a session.

You build the full URL for each endpoint by concatenating the pool's management API endpoint with the endpoint path. The query string must include an identifier parameter containing the session identifier, and an api-version parameter with the value 2024-02-02-preview. API versions can change, so always confirm the latest version in the REST API docs before using it in production.

For example: {sessionManagementEndpoint}/code/execute?api-version=2024-02-02-preview&identifier=<IDENTIFIER>

For REST API references, see Container Apps data-plane APIs and the Container Apps data-plane operations overview.

Custom container session pool

To create a custom container session pool, you need to provide a container image and pool configuration settings.

You invoke or communicate with each session using HTTP requests. The custom container must expose an HTTP server on a port that you specify to respond to these requests.

The following capabilities apply only to custom container session pools.

Custom container management endpoint

For custom container session pools, get the management endpoint from the Azure portal or the Azure CLI output. The endpoint is returned as poolManagementEndpoint.

The endpoint is in the format https://<SESSION_POOL_NAME>.<ENVIRONMENT_ID>.<REGION>.azurecontainerapps.io.

OnContainerExit

With the OnContainerExit lifecycle, a session remains active until the container exits on its own or the maximum alive period is reached.

{
  "dynamicPoolConfiguration": {
    "lifecycleConfiguration": {
      "maxAlivePeriodInSeconds": 6000,
      "lifecycleType": "OnContainerExit"
    }
  }
}

Property	Description
`maxAlivePeriodInSeconds`	Maximum time the session can stay alive before being deleted.
`cooldownPeriodInSeconds`	Not supported for `OnContainerExit` lifecycle.

Container probes

Container probes let you define health checks for session containers so the pool can detect unhealthy sessions and replace them to keep the readySessionInstances target healthy.

Session pools support Liveness and Startup probes. For more information about probe behavior, see Health probes in Azure Container Apps.

When creating or updating a session pool, specify probes in properties.customContainerTemplate.containers. For the complete request body schema, see the SessionPools Create or Update API reference. The following example shows a partial configuration with probe definitions:

{
  "properties": {
    "customContainerTemplate": {
      "containers": [
        {
          "name": "my-session-container",
          "image": "myregistry.azurecr.io/my-session-image:latest",
          "probes": [
            {
              "type": "Liveness",
              "httpGet": {
                "path": "/health",
                "port": 8080
              },
              "periodSeconds": 10,
              "failureThreshold": 3
            },
            {
              "type": "Startup",
              "httpGet": {
                "path": "/ready",
                "port": 8080
              },
              "periodSeconds": 5,
              "failureThreshold": 30
            }
          ]
        }
      ]
    },
    "dynamicPoolConfiguration": {
      "readySessionInstances": 5
    }
  }
}

Azure CLI

Custom container session pools require a workload profiles-enabled Azure Container Apps environment. If you don't have an environment, use the az containerapp env create -n <ENVIRONMENT_NAME> -g <RESOURCE_GROUP> --location <LOCATION> command to create one.

Use the az containerapp sessionpool create command to create a custom container session pool.

The following example creates a session pool named my-session-pool with a custom container image myregistry.azurecr.io/my-container-image:1.0.

Before you send the request, replace the placeholders between the <> brackets with the appropriate values for your session pool and session identifier.

az containerapp sessionpool create \
    --name my-session-pool \
    --resource-group <RESOURCE_GROUP> \
    --environment <ENVIRONMENT> \
    --registry-server myregistry.azurecr.io \
    --registry-username <USER_NAME> \
    --registry-password <PASSWORD> \
    --container-type CustomContainer \
    --image myregistry.azurecr.io/my-container-image:1.0 \
    --cpu 0.25 --memory 0.5Gi \
    --target-port 80 \
    --cooldown-period 300 \
    --network-status EgressDisabled \
    --max-sessions 10 \
    --ready-sessions 5 \
    --env-vars "key1=value1" "key2=value2" \
    --location <LOCATION>

This command creates a session pool with the following settings:

Parameter	Value	Description
`--name`	`my-session-pool`	The name of the session pool.
`--resource-group`	`my-resource-group`	The resource group that contains the session pool.
`--environment`	`my-environment`	The name or resource ID of the container app's environment.
`--container-type`	`CustomContainer`	The container type of the session pool. Must be `CustomContainer` for custom container sessions.
`--image`	`myregistry.azurecr.io/my-container-image:1.0`	The container image to use for the session pool.
`--registry-server`	`myregistry.azurecr.io`	The container registry server hostname.
`--registry-username`	`my-username`	The username to log in to the container registry.
`--registry-password`	`my-password`	The password to log in to the container registry.
`--cpu`	`0.25`	The required CPU in cores.
`--memory`	`0.5Gi`	The required memory.
`--target-port`	`80`	The session port used for ingress traffic.
`--cooldown-period`	`300`	The number of seconds that a session can be idle before the session is terminated. The idle period is reset each time the session's API is called. Value must be between `300` and `3600`.
`--network-status`	`EgressDisabled`	Specifies whether outbound network traffic is allowed from the session. Valid values are `EgressDisabled` (default) and `EgressEnabled`.
`--max-sessions`	`10`	The maximum number of sessions that can be allocated at the same time.
`--ready-sessions`	`5`	The target number of sessions that are ready in the session pool all the time. Increase this number if sessions are allocated faster than the pool is being replenished.
`--env-vars`	`"key1=value1" "key2=value2"`	The environment variables to set in the container.
`--location`	`"Supported Location"`	The location of the session pool.

To update the session pool, use the az containerapp sessionpool update command.

Azure portal

Custom container session pools require a workload profiles-enabled Azure Container Apps environment.

Sign in to the Azure portal.
In the search bar at the top of the portal, search for and select Container Apps Session Pools.
Select Create.

In the Basics tab, enter the following values:

Setting	Action
Subscription	Select your Azure subscription.
Resource group	Select an existing resource group or select Create new.
Session pool name	Enter a name for your session pool.
Pool type	Select Custom container.
Maximum concurrent sessions	Enter the maximum number of sessions that can be allocated at the same time.
Session cooldown period (seconds)	Enter the number of idle seconds before a session is terminated. The allowed range is `300` to `3600`.
Ready session instances	Enter the target number of sessions to keep ready in the pool at all times.
Network egress	Select Disabled to block outbound traffic, or Enabled to allow it.

In the Container Apps environment section, enter the following values:

Setting Action

Region Select a supported region.

Container Apps environment Select an existing environment or select Create new environment.

[!NOTE] The environment houses your Log Analytics workspace. You can also add a virtual network and Application Insights. To see environments from all regions, select Show environments in all regions.

Setting	Action
Region	Select a supported region.
Container Apps environment	Select an existing environment or select Create new environment.

In the Container tab, enter the following values:

In the Session custom container source section, enter the following values:

Setting	Action
Name	Enter a name for the container.
Build type	Select the build type for the container.
Subscription	Select the subscription that contains your container registry.
Registry	Select your container registry.
Image	Select the container image.
Image tag	Select the image tag.
Command override	(Optional) Enter a command to override the container's default entrypoint. Example: `/bin/bash`.
Arguments override	(Optional) Enter arguments to pass to the command override. Example: `-c, while true; do echo hello; sleep 10; done`.

[!NOTE] You can update these settings after creating the session pool.

In the Ingress section, enter the following value:

Setting	Action
Target port	Enter the port that the session container exposes for HTTP traffic. Default is `80`.

In the Container resource allocation section, select the CPU and memory allocation for the container.

Optionally, add environment variables in the Environment variables section.

Select Review + create.
After validation passes, select Create.

Azure Resource Manager

To use Azure Resource Manager for session pools, see the SessionPools REST API overview.

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Use session pools in Azure Container Apps

Common concepts for both pools

Configure a pool

Session lifecycle configuration

Timed (default)

Management endpoint

Image caching

Code interpreter session pool

Azure CLI

Azure portal

Code interpreter management endpoint

Custom container session pool

Custom container management endpoint

OnContainerExit

Container probes

Azure CLI

Azure portal

Azure Resource Manager

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Use session pools in Azure Container Apps

Common concepts for both pools

Configure a pool

Session lifecycle configuration

Timed (default)

Management endpoint

Image caching

Code interpreter session pool

Azure CLI

Azure portal

Code interpreter management endpoint

Custom container session pool

Custom container management endpoint

OnContainerExit

Container probes

Azure CLI

Azure portal

Azure Resource Manager

Related content