aws-lambda.md

AWS Lambda

Today I learnt ...

... how to quickly iterate on a nodejs function that uses other AWS services

2024-01-23T12:32:03+00:00 A nodejs script with dependencies can be zipped and function code updated using the aws-cli

Prerequisites

• aws-cli

  • https://docs.aws.amazon.com/cli/latest/userguide/cli-chap-welcome.html

• An [sqs.md](SQS queue)

Recipe

1. Create the Role

   Create the role and attach a policy to the role that grants permissions to the lambda function to log to CloudWatch

   Expand for code

   pwd /home/jon/code/today-i-learned
   cd assets/aws-lambda
   aws iam create-role --role-name til-lambda-example-role --assume-role-policy-document file://trust-policy.json;
   
   aws iam attach-role-policy --role-name til-lambda-example-role --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
   

   
   

2. Create a barebones Lambda with aws-cli

   See the start version of the lambda: assets/aws-lambda/start/index.js

   Add this file to a zip and run aws lambda create-function populating the ARN to the role with your AWS account number.

   Expand for code

   cd assets/aws-lambda/start/
   zip -r9 lambda.zip index.js package.json;
   
   aws lambda create-function --function-name til-lambda-example --runtime nodejs20.x --zip-file fileb://lambda.zip --handler index.handler --role "arn:aws:iam::YOUR_ACCOUNT_NUMBER:role/til-lambda-example-role"
   

   
   

3. Invoke the Lambda with aws-cli

   To test the basic lambda has been created, invoke it passing a sample payload event.json

   After running the code, look in response.json

   Expand for code

   aws lambda invoke --function-name til-lambda-example --payload file://event.json response.json;
   
   cat response.json
   {"headers":{"Content-Type":"application/json"},"statusCode":200,"body":"{\"success\":true}"}%    
   

   
   

4. Now we know we can invoke a simple lambda, let's try one with packages.

   We'll use the existing lambda function and use the https://awscli.amazonaws.com/v2/documentation/api/latest/reference/lambda/update-function-code.html aws-cli method to update the code.

   In the script's directory, install packages, create a new zip, and update the function code.

   Expand for code

   cd ../packages
   npm install
   
   zip -r9 lambdapackages.zip .
   aws lambda update-function-code --function-name til-lambda-example --zip-file fileb://lambdapackages.zip
   
   # Invoke lambdapackages remotely
   aws lambda invoke --function-name til-lambda-example --payload file://event.json response.json
   cat response.json
   {"headers":{"Content-Type":"application/json"},"statusCode":200,"body":"{\"success\":true}"}%    

   
   

5. Iterate accordingly.

   Modify your code, rezip, update the function code and run it

   Expand for code

   rm -rf lambdapackages.zip; 
   
   zip -r9 lambdapackages.zip .
   aws lambda update-function-code --function-name til-lambda-example --zip-file fileb://lambdapackages.zip
   
   
   aws lambda invoke --function-name til-lambda-example --payload file://event.json response.json
   cat response.json
   {"headers":{"Content-Type":"application/json"},"statusCode":200,"body":"{\"success\":true}"}%    

   
   

6. Remove role and lambda when you've finished.

   Expand for code

   aws lambda delete-function --function-name til-lambda-example;
   
   aws iam delete-role --role-name til-lambda-example-role

Resources

• https://stackoverflow.com/a/34439125

• https://bobbyhadz.com/blog/aws-cli-create-lambda-function

• https://awscli.amazonaws.com/v2/documentation/api/latest/reference/lambda/index.html

• https://docs.aws.amazon.com/lambda/latest/dg/lambda-nodejs.html

• Update environment variables

  • https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html
  • https://awscli.amazonaws.com/v2/documentation/api/latest/reference/lambda/update-function-configuration.html

  • aws lambda update-function-configuration --function-name til-lambda-example --environment "Variables={JW_AWS_ACCESS_KEY_ID=XXX,JW_AWS_SECRET_ACCESS_KEY=YYY}"