lambda-api

A simple AWS Lambda function accessible via API Gateway.

Testing

python3 -m pip install -r requirements.txt

pytest

Deploy

Suitable to be deployed in AWS free tier.

Provide AWS credentials in one of the usual ways, verify variables.tf, and execute:

terraform apply

This will print:

api_route = "https://<some_id>.execute-api.ap-south-1.amazonaws.com/v1/list-bucket-content"

You may then add content to the bucket and use this endpoint to list files/folders.

gunjan@FocalUbuntu:~/python workspace/lambda-api$ curl $api_route
{"contents": ["dir1", "dir2"]}
gunjan@FocalUbuntu:~/python workspace/lambda-api$ curl $api_route/dir2
{"contents": ["file2", "file1"]}
gunjan@FocalUbuntu:~/python workspace/lambda-api$ curl $api_route/whatever
{"error": "No such folder whatever in S3 bucket gunjantest"}
gunjan@FocalUbuntu:~/python workspace/lambda-api$ 

A demo is available at https://rzyq4xmmvg.execute-api.ap-south-1.amazonaws.com/v1/list-bucket-content

Tear down

terraform destroy

You may need to empty the bucket first.

Design decisions

• Lambda has:
  • latest python runtime with boto3
  • easy to grant permissions to bucket
  • easy logging via CloudWatch
• API Gateway has:
  • good integration with Lambda (Lambda Proxy Integration)
  • public, https endpoint

Projects that made this easier:

• Terraformer:
  Creates basic terraform stubs from existing AWS resources, as a starting point.
  Note: Generated files have hardcoded ids. You need to define dependencies yourself.
  Note: liberally use terraform import command to actually import resources into tfstate.
• pytest: Use familiar assert to write test cases. Auto detect test cases.