Parse UserParameters sent from AWS CodePipeline to AWS Lambda in Go

#aws #go #awscodepipeline #awslambda

Context

I was trying to setup the UserParameters configuration within the AWS CodePipeline Template being generated,

Name: ...
Actions:
  - Name: Invoke-Lambda
    ActionTypeId:
      Category: Invoke
      Owner: AWS
      Provider: Lambda
      Version: '1'
    Configuration:
      FunctionName: exampleLambdaFunction
      UserParameters: '{"example":"user-parameters"}'

While testing it out on an AWS Lambda, written in Go, it took a bit longer than usual to find out the Function Definition for the Handler, to parse the AWS CodePipeline JSON Event that would be sent, For Example:

{
    "CodePipeline.job": {
        "id": "11111111-abcd-1111-abcd-111111abcdef",
        "accountId": "111111111111",
        "data": {
            "actionConfiguration": {
                "configuration": {
                    "FunctionName": "exampleLambdaFunction",
                    "UserParameters": "{\"example\":\"user-parameters\"}"
                }
            },
            "inputArtifacts": [
               ...
            ],
            ...
        }
    }
}

Solution

Use the github.com/aws/aws-lambda-go/events package link which contains the events.CodePipelineJobEvent that helps unmarshal the AWS CodePipeline JSON event being sent

package main

import (
    "context"
    "fmt"
    "github.com/aws/aws-lambda-go/events"
    "github.com/aws/aws-lambda-go/lambda"
)

func Handler(ctx context.Context, event events.CodePipelineJobEvent) (string, error) {
    fmt.Printf("received codepipeline event function name: %+v\n", event.CodePipelineJob.Data.ActionConfiguration.Configuration.FunctionName)
    fmt.Printf("received codepipeline event user parameters: %+v\n", event.CodePipelineJob.Data.ActionConfiguration.Configuration.UserParameters)
    return "cool", nil
}

func main() {
    lambda.Start(Handler)
}