CI: check server metadata on a schedule

[thekaveman]

Closes #515

Todo

• Release Feat: metadata endpoint #512 to dev, test, and prod
• Create ACTION_MONITORING_SLACK secret
• Fill secret value for ACTION_MONITORING_SLACK
• Create METADATA_CHECK_CONFIG secret
• Fill secret value for METADATA_CHECK_CONFIG:

{
  "mst": "https://production-server-url.com/metadata",
  "sbmtd": "https://production-server-url.com/metadata",
}

Reviewing

Success path

1. Checkout the branch locally, open in devcontainer

2. Create a file metadata.json at the root, with contents:

   {
     "cst": "http://localhost:8000/metadata"
   }

3. Run flask init-db to ensure metadata is hydrated

4. F5 to run the app

5. Run the check-metadata script: python .github/workflows/check-metadata.py cst

6. Confirm no error output. Zero exit code.

Fail path

1. Modify eligibility_server/db/setup.py to make metadata.timestamp something other than the correct current date (e.g. change day, month, and/or year)
2. Run flask init-db again to hydrate new metadata
3. F5 to run the app
4. Run the check-metadata script: python .github/workflows/check-metadata.py cst
5. Confirm error output indicates a timestamp mismatch. Non-zero exit code.

Redo the preceding steps to:

• Make metadata.users 0
• Make metadata.eligibility an empty list

And in each case, confirm the check-metadata.py script fails accordingly.

[github-actions]

Coverage report

This PR does not seem to contain any modification to coverable code.

[thekaveman]

Closing this in favor of a workflow in the Benefits repo: cal-itp/benefits#2610