[CT-3488] [Feature] Generate manifest at build time or in PR

[colin-rogers-dbt]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Currently dbt-core relies on a delicate mechanism to generate a manifest: https://github.com/dbt-labs/dbt-core/blame/6e0a38720529360d061bd4e24e140f5ec55f8c15/tests/functional/artifacts/test_previous_version_state.py#L414

Instead of relying on commenting/uncommenting out test code we should generate this as part of our CI process either on the PR or in the release.

The current setup risks us to accidentally merge a manifest change: #9195 (comment) and is unintuitive for core development

Describe alternatives you've considered

No response

Who will this benefit?

No response

Are you interested in contributing this feature?

No response

Anything else?

No response

[emmyoop]

@colin-rogers-dbt this isn't quite accurate. That line generates a manifest off the test project that we use to test backwards compatibility. It's not generating the new schema. It affects only the test, not dbt as a released product. The changes in the linked PR were likely timestamps so not significant. However this is not the first time those methods were not commented back out before merging a PR. This is not an ideal solution for generating the new test manifest.

[colin-rogers-dbt]

Thanks for the clarification @emmyoop !

[dbeatty10]

What do you see as the next steps here @emmyoop or @colin-rogers-dbt ?

Is it to determine an alternative mechanism to #5604 that would allow generating a new manifest that doesn't rely on remembering to re-comment an uncommented line?

Like reading an environment variable here (or something else)?

        # If we need a newly generated manifest, set the DBT_GENERATE_MANIFEST environment variable
        if os.getenv("DBT_GENERATE_MANIFEST"):
            self.generate_latest_manifest(project, current_schema_version)

[emmyoop]

One option is to have a make command that would generate the file for us. We're already use ing it to do things like generate new proto definitions.

[dbeatty10]

@colin-rogers-dbt would it meet the need to remove these lines altogether and replace it with a command in the Makefile similar to the one for generating protos?