tools: detect changes between builds

[nmoutschen]

Proposed change

This change would prevent building resources that are already built and thus lower the iteration time for development changes.

On the first make build for a given service, it will create a .checksum file in the build folder. This file will be a checksum of all the relevant files for the build command. There could be multiple checksum files for different build operations (e.g. CloudFormation, OpenAPI, Python code, etc.).

On subsequent runs, this would check the checksum file(s) and compare them to the checksums of the existing files. If there are no differences, this will skip the build step and consider it as successful.

Risks

If files outside of the service folder are changed (e.g. files in shared/src/ecom/), this could create discrepancies between the development environments and what would be built in the CI/CD pipeline. This could be overcome with the detection of changes within shared libraries.