Linux academy: Creating AWS Lambda Versions and Aliases via the AWS CLI

Introduction

In this hands-on lab, we'll create Lambda function versions and aliases via the AWS CLI.

Solution

Open a terminal session, and log in to the server via SSH using the credentials provided on the lab page:

ssh cloud_user@<PUBLIC_IP_ADDRESS>

In the browser, log in to the live AWS environment using the credentials provided, and make sure you're in the N. Virginia (us-east-1) region.

All of the code used in the lesson is available for download here.

Lab Prep

1. In AWS, navigate to IAM > Roles.
2. Click the lambda_exec_role_LA role listed.
3. Copy the ARN and paste it into a text file. We'll need it later.

4. In the terminal, make sure AWS CLI is installed by running:

   aws help

   You should see it's installed.

Create Your Lambda Function

1. In the terminal, run:

   vim lambda_function.py

2. Paste in the code from GitHub.

3. Save and exit the file.

4. Zip the file:

   zip lambda_function.zip lambda_function.py

5. Create the function (replacing <lambda_exec_role_LA_ARN> with the ARN you copied earlier):

   aws lambda create-function --function-name SnapShot \ --description "Taking EBS Snaps" \ --memory-size 1024 \ --timeout 10 \ --handler lambda_function.handler \ --runtime "python3.6" \ --role "<lambda_exec_role_LA_ARN>" \ --zip-file fileb:///home/cloud_user/lambda_function.zip \ --region us-east-1

Publish Your First Version

1. Publish a new version:

   aws lambda publish-version \ --function-name SnapShot \ --region us-east-1

2. Check the versions:

   aws lambda list-versions-by-function \ --function-name SnapShot --region us-east-1

Create Your Alias

1. Create the alias:

   aws lambda create-alias \ --function-name SnapShot \ --description "Production Alias" \ --function-version 1 \ --name PROD \ --region us-east-1

2. Check the aliases:

   aws lambda list-aliases \ --function-name SnapShot \ --region us-east-1

Create Your CloudWatch Event Rule/Trigger

1. Add a permission for events to invoke the function alias:

   aws lambda add-permission \ --function-name SnapShot \ --qualifier PROD \ --statement-id 001 \ --principal events.amazonaws.com \ --action lambda:InvokeFunction \ --region us-east-1

2. Copy the ARN listed in the output and paste it into a text file, as we'll need it later.

3. Create the CloudWatch rule:

   aws events put-rule \ --name "EC2-SNAP" \ --schedule-expression "rate(2 minutes)" \ --state "ENABLED" \ --description "Takes EBS Snapshot of volumes on a scheduled basis." \ --region us-east-1

4. Add a target to the rule (replacing <PROD_ARN> with the one you copied a minute ago):

   aws events put-targets \ --rule "EC2-SNAP" \ --targets "Id"="1","Arn"="<PROD_ARN>" \ --region us-east-1

5. Pause the rule:

   aws events disable-rule \ --name EC2-SNAP \ --region us-east-1

6. Verify your output.

Publish a New Version and Remap Your Alias

1. Update the code:

   vim lambda_function.py

2. Paste in the updated code from GitHub.

3. Save and exit the file.

4. Zip the file:

   !zip zip lambda_function.zip lambda_function.py

5. Upload your updated function code to Lambda:

   aws lambda update-function-code \ --function-name SnapShot \ --zip-file fileb:///home/cloud_user/lambda_function.zip \ --region us-east-1

6. Publish a new version from that updated code base:

   aws lambda publish-version \ --function-name SnapShot \ --region us-east-1

7. Once created, remap your alias to Version 2:

   aws lambda update-alias \ --function-name SnapShot \ --name PROD \ --function-version 2 \

8. Check the alias:

   aws lambda list-aliases \ --function-name SnapShot \ --region us-east-1

9. Re-enable the rule:

   aws events enable-rule \ --name EC2-SNAP \ --region us-east-1