AWS Lambda extensions are companion processes that augment your Lambda functions. They run within the Lambda execution environment, alongside your Lambda function code. The Datadog extension is a lightweight version of the Datadog Agent built to run alongside your code with minimal performance overhead.
The Datadog Lambda Extension is responsible for:
The Datadog extension submits custom metrics, enhanced metrics, traces and logs asynchronously. Submitting Lambda logs with the extension is supported in all Lambda runtimes. Submitting custom metrics, enhanced metrics and traces is supported in Node.js, Python, Go and Java Lambda runtimes.
To install the Datadog Lambda Extension and instrument your AWS serverless applications, see the serverless installation instructions.
To disable submission of your AWS Lambda logs to Datadog using the extension, set the environment variable DD_SERVERLESS_LOGS_ENABLED to false in your Lambda function.
To disable submission of your AWS Lambda traces to Datadog using the extension, set the environment variable DD_TRACE_ENABLED to false in your Lambda function.
When using the Extension, Datadog recommends you apply tags by adding the following environment variables to your Lambda functions:
DD_ENV: This sets the env tag in Datadog. Use it to separate out your staging, development, and production environments.DD_SERVICE: This sets the service tag in Datadog. Use it to group related Lambda functions into a service.DD_VERSION: This sets the version tag in Datadog. Use it to enable Deployment Tracking.DD_TAGS: This sets custom tags in Datadog. Must be a list of <key>:<value> separated by commas such as: layer:api,team:intake.If you have the Datadog AWS integration enabled, any AWS resource tag applied to your AWS Lambda function also gets applied in Datadog automatically.
The Datadog Lambda Extension introduces a small amount of overhead to your Lambda function’s cold starts (that is, the higher init duration), as the Extension needs to initialize. Datadog is continuously optimizing the Lambda extension performance and recommend always using the latest release.
You may also notice increase of your Lambda function’s reported duration, and this is because the Datadog Lambda Extension needs to flush data back to the Datadog API. Although the time spent by the Extension flushing data is reported as part of the duration, it’s done after AWS returning your function’s response back to the client. In other words, the added duration does not slow down your Lambda function. Additional technical details can be found from this AWS blog post.
By default, the Extension sends data back to Datadog at the end of each invocation. This avoids delays of data arrival for sporadic invocations from low-traffic applications, cron jobs, and manual tests. Once the Extension detects a steady and frequent invocation pattern (more than once per minute), it batches data from multiple invocations and flushes periodically at the beginning of the invocation when it’s due. This means that the busier your function is, the lower the average duration overhead per invocation.
For Lambda functions deployed in a region that is far from the Datadog site, for example, a Lambda function deployed in eu-west-1 reporting data to the US1 Datadog site, can observe a higher duration overhead due to the network latency. You can set the environment variable DD_SERVERLESS_FLUSH_STRATEGY with value periodically,30000 on your Lambda functions to flush data every 30s, instead of the default every 10s, and this usually results in a significantly lower average duration overhead per invocation.
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