Support the RDS PostgreSQL `aws_lambda` extension

[juman-y]

I would like to use this extension in fakecloud-managed PostgreSQL/RDS instances so that SQL running in the database can invoke Lambda functions directly, for example with aws_lambda.invoke(...).

LocalStack documents this feature here, and I would like fakecloud to provide compatible behavior as well:
https://docs.localstack.cloud/aws/services/rds/#aws_lambda-extension

Expected SQL:

CREATE EXTENSION IF NOT EXISTS aws_lambda CASCADE;

SELECT aws_commons.create_lambda_function_arn('my_function');

SELECT aws_lambda.invoke('my_function', '{"body": "Hello!"}'::json);

The invocation should call the corresponding fakecloud Lambda function and return a response compatible with AWS RDS PostgreSQL behavior.

This would help me run local integration tests for applications that rely on RDS PostgreSQL invoking Lambda functions from SQL.

[vieiralucas]

Hi @juman-y — shipped in v0.13.1, released today.

Your example works as written:

CREATE EXTENSION IF NOT EXISTS aws_lambda CASCADE;
SELECT aws_commons.create_lambda_function_arn('my_function');
SELECT aws_lambda.invoke('my_function', '{"body": "Hello!"}'::json);

A few notes on the implementation:

• aws_commons.create_lambda_function_arn(function_name, region DEFAULT NULL) returns the same composite type AWS uses, so the helper composes with aws_lambda.invoke overloads exactly like AWS RDS / Aurora.
• aws_lambda.invoke has the four standard signatures (text+json / composite+json, with optional region and invocation_type). It posts to a new /_fakecloud/rds/lambda-invoke bridge inside the container and resolves the function ARN against the fakecloud Lambda service, so any Lambda runtime fakecloud supports works.
• We also published prebuilt PostgreSQL images at ghcr.io/faiscadev/fakecloud-postgres:<major>-0.13.1 (pg13/14/15/16, linux/amd64 + linux/arm64), so the first CreateDBInstance no longer pays the ~60s extension build. Local build still kicks in as a fallback for offline / unreleased setups.

Upgrade notes are on the release page: https://github.com/faiscadev/fakecloud/releases/tag/v0.13.1.

If anything in your integration test setup behaves differently from AWS RDS, please reopen — happy to chase parity gaps. Thanks for the clean repro in the original issue, made the design straightforward.