# Configure Lambda durable functions
<a name="durable-configuration"></a>

Durable execution settings control how long your Lambda function can run and how long the service retains execution history. Configure these settings to enable durable execution for your function.

## Enable durable execution
<a name="durable-config-settings"></a>

Configure the `DurableConfig` object when creating your function to set execution timeout and history retention. You can only enable durable execution when creating a function. You cannot enable it on existing functions.

------
#### [ AWS CLI ]

```
aws lambda create-function \
  --function-name my-durable-function \
  --runtime nodejs24.x \
  --role arn:aws:iam::123456789012:role/my-durable-role \
  --handler index.handler \
  --zip-file fileb://function.zip \
  --durable-config '{"ExecutionTimeout": 3600, "RetentionPeriodInDays": 30}'
```

------
#### [ CloudFormation ]

```
Resources:
  MyDurableFunction:
    Type: AWS::Lambda::Function
    Properties:
      FunctionName: my-durable-function
      Runtime: nodejs24.x
      Handler: index.handler
      Code:
        ZipFile: |
          // Your durable function code
      DurableConfig:
        ExecutionTimeout: 3600
        RetentionPeriodInDays: 30
```

------

**Configuration parameters:**
+ `ExecutionTimeout` – The maximum time in seconds that a durable execution can run before Lambda stops the execution. This timeout applies to the entire durable execution, not individual function invocations. Valid range: 1–31622400.
+ `RetentionPeriodInDays` – The number of days to retain execution history after a durable execution completes. After this period, execution history is no longer available through the `GetDurableExecutionHistory` API. Valid range: 1–90.

For the full API reference, see [DurableConfig](https://docs.aws.amazon.com/lambda/latest/api/API_DurableConfig.html) in the Lambda API Reference.

## Configuration best practices
<a name="durable-config-best-practices"></a>

Follow these best practices when configuring durable functions for production use:
+ **Set appropriate execution timeouts** – Configure `ExecutionTimeout` based on your workflow's maximum expected duration. Do not set unnecessarily long timeouts as they affect cost and resource allocation.
+ **Balance retention with storage costs** – Set `RetentionPeriodInDays` based on your debugging and audit requirements. Longer retention periods increase storage costs.
+ **Monitor state size** – Large state objects increase storage costs and can impact performance. Keep state minimal and use external storage for large data.
+ **Configure appropriate logging** – Enable detailed logging for troubleshooting long-running workflows, but consider the impact on log volume and costs.

**Production configuration example:**

```
{
  "ExecutionTimeout": 86400,
  "RetentionPeriodInDays": 7
}
```

This example sets a 24-hour (86,400 seconds) execution timeout with a 7-day retention period, which balances debugging visibility with storage costs for most production workloads.