lambda

Example: Lambda

This example shows how to use the X-Ray plugin for httpx on Lambda.

Outcome

This example provides a Lambda Function demonstrating how the httpx plugin (httpxxray) produces X-Ray traces when run on Lambda.

When you invoke the Lambda Function, it starts a "local" HTTPS server running within the Lambda sandbox and executes a simple GET request to the server using an httpx.Client with the plugin installed. The first 4 attempts cause various errors necessitating retry; the fifth attempt succeeds. The final X-Ray trace thus shows one execution with 5 attempts as shown below.

Steps

1. Build the example binary for a Lambda Function.
2. Create and configure your Lambda Function.
3. Invoke your Lambda Function.
4. View the generated trace in the AWS X-Ray console.

1. Build Lambda binary

Build the example binary using the below commands:

$ go get github.com/gogama/aws-xray-httpx/example/lambda
$ GOOS=linux go install github.com/gogama/aws-xray-httpx/example/lambda

The above will download the example source code and build an executable binary named lambda which can be used as an AWS Lambda Function. The binary will be built to the directory GOBIN or, if go env GOBIN is blank, the directory $(go env GOPATH)/bin.

Now change directories to GOBIN (if go env GOBIN is blank this is just the current working directory) and create a ZIP file containing the built binary:

$ zip lambda.zip lambda

If you struggle with this step, you may find the AWS Docs "Blank Go Lambda Function" example project to be helpful.

2. Create and configure your Lambda Function

The below steps explain how to set up the Function using the AWS Lambda console, but you may also use the AWS CLI.

1. In the AWS console, create a new Lambda Function named example_lambda using the "Go 1.x" runtime.
2. After creating your new Function, configure it:
   • On the Code tab, edit the runtime settings to set the handler name to lambda.
   • On the Code tab, upload the lambda.zip file you created in the previous step.
   • On the Configuration tab, go to "Monitoring and operations tools" and set enable Active tracing.

3. Invoke your Lambda Function

In the Lambda console, use the Test tab to invoke your new Function with a test event.

Your example Function requires a string input (which it ignores) and Lambda requires that you use valid JSON as the input, so use a bare JSON string as the input, e.g. "test".

The logged output should look similar to this:

START RequestId: bad4bec3-b5f8-486a-b8f7-a8759eddd079 Version: $LATEST
2021-03-31T15:17:13Z [INFO] Emitter using address: 169.254.79.2:2000
END RequestId: bad4bec3-b5f8-486a-b8f7-a8759eddd079
REPORT RequestId: bad4bec3-b5f8-486a-b8f7-a8759eddd079	Duration: 626.70 ms	Billed Duration: 627 ms	Memory Size: 512 MB	Max Memory Used: 42 MB	Init Duration: 102.08 ms
XRAY TraceId: 1-60649279-76721ac003b4127a585ff482	SegmentId: 69b784723afaa375	Sampled: true

4. View trace in X-Ray console

In the AWS console, navigate to AWS X-Ray.

Select Traces and view the most recent trace. If your Lambda function's trace does not appear, it is likely because you forgot to enable Active tracing.