go-example-logs-api-extension

Example Logs API Extension in Go

The provided code sample demonstrates how to get a basic Logs API extension written in Go up and running.

This is a simple example extension to help you start investigating the Lambda Runtime Logs API. This example code is not production ready. Use it with your own discretion after testing thoroughly.

This sample extension:

• Subscribes to recieve platform and function logs
• Runs with a main and a helper goroutine: The main goroutine registers to ExtensionAPI and process its invoke and shutdown events (see nextEvent call). The helper goroutine:
  • starts a local HTTP server at the provided port (default 1234) that receives requests from Logs API
  • puts the logs in a synchronized queue (Producer) to be processed by the main goroutine (Consumer)
• Writes the received logs to an S3 Bucket

Compile package and dependencies

To run this example, you will need to ensure that your build architecture matches that of the Lambda execution environment by compiling with GOOS=linux and GOARCH=amd64 if you are not running in a Linux environment.

Building and saving package into a bin/extensions directory:

$ cd go-example-logs-api-extension
$ GOOS=linux GOARCH=amd64 go build -o bin/extensions/go-example-logs-api-extension main.go
$ chmod +x bin/extensions/go-example-logs-api-extension

Layer Setup Process

The extensions .zip file should contain a root directory called extensions/, where the extension executables are located. In this sample project we must include the go-example-logs-api-extension binary.

Creating zip package for the extension:

$ cd bin
$ zip -r extension.zip extensions/

Publish a new layer using the extension.zip and capture the produced layer arn in layer_arn. If you don't have jq command installed, you can run only the aws cli part and manually pass the layer arn to aws lambda update-function-configuration.

layer_arn=$(aws lambda publish-layer-version --layer-name "go-example-logs-api-extension" --region "<use your region>" --zip-file  "fileb://extension.zip" | jq -r '.LayerVersionArn')

Add the newly created layer version to a Lambda function.

aws lambda update-function-configuration --region <use your region> --function-name <your function name> --layers $layer_arn

Function Invocation and Extension Execution

Note: Your function role should have the AmazonS3FullAccess policy attached.

Note: You need to add LOGS_API_EXTENSION_S3_BUCKET environment variable to your lambda function. The value of this variable will be used to create a bucket or use an existing bucket if it is created previously. The logs received from Logs API will be written in a file inside that bucket. For S3 bucket naming rules, see AWS docs.

After invoking the function and receiving the shutdown event, you should now see log messages from the example extension written to an S3 bucket with the following name format:

<function-name>-<timestamp>-<UUID>.log in to the bucket set with the environment variable above.