Feature request: Include/Exclude Interface for AWS Lambda Builders

[mildaniel]

Describe your idea/feature/enhancement

There are currently two opposing feature requests that go hand-in-hand. One is to include files/directories in the resultant build package, and one is for exclusion. Both of these are genuine use-cases across various runtimes, and, as such, we believe should be handled together though a common include/exclude interface for the Lambda Builders library.

Include: Issue #430, PR #431
Exclude: Issue #185, PR #424

This should start with an initial design document, and once approved, can be implemented. The important notes for the design to address:

• What does the interface look like? e.g. is part of the JSON RPC, is it through a configuration file, etc?
• How to make the implementation general across runtimes. Are there any runtimes for which this feature should be ignored?

[AdrianCarreno]

I think the functionality should be just like .gitignore or .dockerignore. Just have a .samignore file where you would put every path you don't want in the build.

[farridav]

👍 Having an optional .samignore file that overides the hardcoded EXCLUDED_FILES seems like natural behaviour to me, afterall

Explicit is better than implicit - Zen of Python

It fits with developer expectations set by many other mature tools and could easily be a non breaking change by defaulting to the hardcoded EXCLUDED_FILES when this file is not present..

[ishan1608]

Has there any progress been made on this so far, to come up with a decision?
We are facing similar stuff in our project, where we have a bunch of stuff like tests, tools etc. being added to the deployed code which we don't really need and is also causing our bundled zip files to become bloated.

[borkke]

I think it should also support nested .samignore files, this could simplify the build process, and local setup for Python projects at least.

For example, I could have a normal multi-package Python app with similar folder structure.

├── sam_structure
│   ├── shared
│   │   ├── __init__.py
│   │   ├── .samignore     # nested (can include "shared")
│   │   └── utils.py
│   ├── activity
│   │   ├── __init__.py
│   │   ├── __pycache__
│   │   ├── app.py
│   │   ├── .samignore.    # nested (can include "shared")
│   │   └── service.py
│   └── location
│       ├── __init__.py
│       ├── __pycache__
│       ├── app.py
│       ├── .samignore      # nested
│       └── service.py
├── template.yaml
├── .samignore             # global (for cache folders for example)

The nested ignore files could exclude/include only what is relevant for the function. What's nice about this is that I can maintain exactly the same folder/package structure across AWS environment, local environment and test runtime. For example, I would use something like this in templates.yaml

CodeUri: .
Handler: sam_structure.activity.app.lambda_handler

and in the test and across the entire application, I don't have to use relative imports anywhere and don't even have to copy shared libraries manually. The Python app should just work everywhere with this import

from sam_structure.activity.service import get_message