Step 3: Create a lifecycle hook Lambda function - Amazon CodeDeploy
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Step 3: Create a lifecycle hook Lambda function

In this section, you implement one Lambda function for your Amazon ECS deployment's AfterAllowTestTraffic hook. The Lambda function runs a validation test before the updated Amazon ECS application is installed. For this tutorial, the Lambda function returns Succeeded. During a real world deployment, validation tests return Succeeded or Failed, depending on the result of the validation test. Also during a real world deployment, you might implement a Lambda test function for one or more of the other Amazon ECS deployment lifecycle event hooks (BeforeInstall, AfterInstall, BeforeAllowTraffic, and AfterAllowTraffic). For more information, see List of lifecycle event hooks for an Amazon ECS deployment.

An IAM role is required to create your Lambda function. The role grants the Lambda function permission to write to CloudWatch Logs and set the status of a CodeDeploy lifecycle hook.

To create an IAM role

  1. Open the IAM console at https://console.amazonaws.cn/iam/.

  2. From the navigation pane, choose Roles, and then choose Create role.

  3. Create a role with the following properties:

    • Trusted entity: Amazon Lambda.

    • Permissions: AWSLambdaBasicExecutionRole. This grants your Lambda function permission to write to CloudWatch Logs.

    • Role name: lambda-cli-hook-role.

    For more information, see Create an Amazon Lambda execution role.

  4. Attach the permission codedeploy:PutLifecycleEventHookExecutionStatus to the role you created. This grants your Lambda functions permission to set the status of a CodeDeploy lifecycle hook during a deployment. For more information, see Adding IAM identity permissions in the Amazon Identity and Access Management User Guide and PutLifecycleEventHookExecutionStatus in the CodeDeploy API Reference.

To create an AfterAllowTestTraffic hook Lambda function

  1. Create a file named AfterAllowTestTraffic.js with the following contents. 

    'use strict';
 
 const AWS = require('aws-sdk');
 const codedeploy = new AWS.CodeDeploy({apiVersion: '2014-10-06'});
 
 exports.handler = (event, context, callback) => {
 
 	console.log("Entering AfterAllowTestTraffic hook.");
 	
 	// Read the DeploymentId and LifecycleEventHookExecutionId from the event payload
  var deploymentId = event.DeploymentId;
 	var lifecycleEventHookExecutionId = event.LifecycleEventHookExecutionId;
 	var validationTestResult = "Failed";
 	
 	// Perform AfterAllowTestTraffic validation tests here. Set the test result 
 	// to "Succeeded" for this tutorial.
 	console.log("This is where AfterAllowTestTraffic validation tests happen.")
 	validationTestResult = "Succeeded";
 	
 	// Complete the AfterAllowTestTraffic hook by sending CodeDeploy the validation status
 	var params = {
 		deploymentId: deploymentId,
 		lifecycleEventHookExecutionId: lifecycleEventHookExecutionId,
 		status: validationTestResult // status can be 'Succeeded' or 'Failed'
 	};
 	
 	// Pass CodeDeploy the prepared validation test results.
 	codedeploy.putLifecycleEventHookExecutionStatus(params, function(err, data) {
 		if (err) {
 			// Validation failed.
 			console.log('AfterAllowTestTraffic validation tests failed');
 			console.log(err, err.stack);
 			callback("CodeDeploy Status update failed");
 		} else {
 			// Validation succeeded.
 			console.log("AfterAllowTestTraffic validation tests succeeded");
 			callback(null, "AfterAllowTestTraffic validation tests succeeded");
 		}
 	});
 }

  2. Create a Lambda deployment package. 

    zip AfterAllowTestTraffic.zip AfterAllowTestTraffic.js

  3. Use the create-function command to create a Lambda function for your AfterAllowTestTraffic hook. 

    aws lambda create-function --function-name AfterAllowTestTraffic \
       --zip-file fileb://AfterAllowTestTraffic.zip \
       --handler AfterAllowTestTraffic.handler \
       --runtime nodejs10.x \
       --role arn:aws:iam::aws-account-id:role/lambda-cli-hook-role

  4. Make a note of your Lambda function ARN in the create-function response. You use this ARN when you update your CodeDeploy deployment's AppSpec file in the next step.