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GitHub App Setup — sap-tutorials-builder

Audience: the SAP GitHub org admin who owns https://github.com/sap-tutorials, and the tutorials-ims repo maintainer who will set the Actions secrets and flip the activation variable. This doc is intentionally short and copy-pasteable.

For the why behind this change, see github-app-migration.md. The short version: replace a long-lived classic PAT (which expires under SAP rotation policy and is tied to one human) with a GitHub App that mints a fresh 1-hour token per workflow run.

What this changes operationally

  • Today: tutorials-ims runs npm run fetch-tutorials in CI using the TUTORIALS_GITHUB_TOKEN secret (a classic PAT). When the PAT expires, the build breaks until someone with access regenerates and re-pastes it.
  • After: the workflow asks GitHub for a short-lived installation token at the start of each run. Nothing to rotate.

What's already in the repo

The workflow change is already merged (see .github/workflows/rebuild-content.yml):

  • A Generate GitHub App token step gated on the repo variable USE_GITHUB_APP == 'true'.
  • The Fetch tutorials step picks steps.app-token.outputs.token || secrets.TUTORIALS_GITHUB_TOKEN.

So:

  • Until the org admin completes setup → the variable stays unset → step is skipped → PAT continues to be used.
  • Once secrets + variable are in place → App token is used automatically.
  • To roll back at any time → set the variable to anything other than true (or delete it).

No code changes required in scripts/parsers/github.ts. Installation tokens are standard Bearer tokens.

Part 1 — Org admin steps (sap-tutorials)

These run once. Estimated time: 15 minutes.

1.1 Register the App

  1. Go to https://github.com/organizations/sap-tutorials/settings/apps/new
  2. Fill in:
    • GitHub App name: sap-tutorials-builder
    • Homepage URL: https://github.com/sap-tutorials/tutorials-ims (or wherever the repo lives)
    • Webhook → Active: uncheck (we don't consume events)
    • Repository permissions:
      • Contents: Read-only (Phase 3 note: bump to Read and write only if you migrate TUTORIALS_POC_DISPATCH_TOKEN — needed for repository_dispatch)
      • Metadata: Read-only (auto-selected)
      • Actions: Read and write (runtime workflow_dispatch from the CAP app — Phase 2)
      • everything else: No access
    • Organization permissions: all No access
    • Account permissions: all No access
    • Where can this GitHub App be installed? Only on this account
  3. Click Create GitHub App.

1.2 Generate a private key

On the App's settings page, scroll to Private keys → Generate a private key. A .pem file downloads automatically. Save this file — you'll paste its contents into a repo secret in Part 2. The key cannot be recovered later; if lost, generate a new one and rotate.

1.3 Note the App ID

At the top of the App's settings page: App ID: XXXXXXX. Copy this number.

1.4 Install the App on the org

  1. On the App settings page, left sidebar → Install App.
  2. Click Install next to sap-tutorials.
  3. Choose either:
    • All repositories (simpler; covers public tutorials + private *-Contribution repos automatically as new ones are added), or
    • Only select repositories → pick every public tutorial repo plus every *-Contribution private repo.
  4. Click Install.
  5. After installation, the URL contains /installations/<INSTALLATION_ID>. Copy this number.

1.5 Hand off to the repo maintainer

Send to whoever owns tutorials-ims Actions secrets:

  • App ID (the number from 1.3)
  • The full contents of the .pem file from 1.2 — paste between -----BEGIN RSA PRIVATE KEY----- and -----END RSA PRIVATE KEY----- inclusive
  • Installation ID (the number from 1.4)

Use a secure channel (e.g. SAP password vault, encrypted email, in-person). Treat the private key like any other credential — anyone with it can mint tokens with the App's permissions.

Part 2 — Repo maintainer steps (tutorials-ims)

These also run once, after Part 1 is complete. Estimated time: 5 minutes.

2.1 Add three Actions secrets

Settings → Secrets and variables → Actions → New repository secret. Add:

Name Value
TUTORIALS_APP_ID App ID from 1.3
TUTORIALS_APP_PRIVATE_KEY Full .pem contents from 1.2 (including BEGIN/END lines)
TUTORIALS_APP_INSTALLATION_ID Installation ID from 1.4 (optional — see note)

The actions/create-github-app-token@v1 action can resolve the installation ID from app-id + owner automatically. The current workflow does not pass installation-id, so this secret is optional. Add it only if you later want to pin a specific installation.

2.2 Flip the activation switch

Same page, Variables tab → New repository variable:

Name Value
USE_GITHUB_APP true

This is a non-secret variable on purpose — it's a feature flag, not a credential, and being non-secret means it shows up clearly in workflow logs.

2.3 Verify with a manual run

  1. Go to Actions → Rebuild Content → Run workflow.
  2. Choose dev, leave slug empty.
  3. Watch the run. You should see:
    • Generate GitHub App token step: ✅ runs (was previously skipped)
    • Fetch tutorials step: ✅ uses the App token (no observable difference in output)
  4. If the run succeeds end-to-end, the migration is complete.

2.4 Cleanup (after one successful unattended run)

Once you've confirmed at least one scheduled or dispatch-triggered run works without manual help:

  1. Delete the TUTORIALS_GITHUB_TOKEN repo secret.
  2. Revoke the underlying classic PAT in the source account's developer settings (so it can't be used elsewhere by accident).

Keep the TUTORIALS_GITHUB_TOKEN secret for at least one full successful run cycle before deleting. It's the rollback path if the App turns out to have a permission gap.

Part 3 — Runtime activation (Phase 2)

The CAP app (tutorials-srv) mints its own installation token via srv/lib/github-app-token.js for the rebuild dispatcher and the two fetch crons. This needs the App secrets in the BTP Credential Store (not just GitHub Actions) plus a runtime flag.

3.1 Load the App secrets into the Credential Store

At /admin-ui/#secrets-display on the target env's approuter, set values for the three registry rows (seeded by scripts/seed-secrets.cjs):

Alias Value
TUTORIALS_APP_ID App ID from 1.3
TUTORIALS_APP_INSTALLATION_ID Installation ID from 1.4
TUTORIALS_APP_PRIVATE_KEY Full .pem contents from 1.2 (multi-line, incl. BEGIN/END)

3.2 Flip the runtime flag

cf set-env tutorials-srv USE_GITHUB_APP true && cf restart tutorials-srv

Verify: trigger an admin save (fires a debounced workflow_dispatch) and confirm rebuild-content ran; check srv logs for [github-app-token] warnings (none expected on success). Roll back with cf set-env tutorials-srv USE_GITHUB_APP false && cf restart tutorials-srv — the PAT path resumes.

Part 4 — Contribution-repo migration (Phase 3)

Each *-Contribution repo fires repository_dispatch at tutorials-ims via notify-qa.yml. To migrate off TUTORIALS_POC_DISPATCH_TOKEN:

  1. Ensure the App is installed on the Contribution repo and holds Contents: write on tutorials-ims (dispatch permission).
  2. Add TUTORIALS_APP_ID + TUTORIALS_APP_PRIVATE_KEY Actions secrets to the Contribution repo.
  3. Set repo variable USE_GITHUB_APP=true on the Contribution repo.
  4. Push a tutorial change; confirm a tutorial-qa-updated dispatch reaches tutorials-ims.
  5. After a clean run, delete TUTORIALS_POC_DISPATCH_TOKEN from that repo.

Roll out per-repo; each is independent.

Rollback

If anything misbehaves after activation:

  1. Set USE_GITHUB_APP repo variable to false (or delete it).
  2. Re-add TUTORIALS_GITHUB_TOKEN secret if it was already deleted.
  3. Re-run the workflow. It falls back to the PAT path automatically.

No code change needed.

Troubleshooting

Symptom Likely cause Fix
Resource not accessible by integration on a *-Contribution repo App not installed on that repo Re-run install (1.4), pick "All repositories" or add the missing repo to the selected list
Bad credentials on GraphQL Private key pasted incorrectly (missing BEGIN/END lines, line endings mangled) Re-paste the .pem exactly as downloaded; GitHub's secret editor preserves newlines correctly when pasted whole
app-token step is skipped even after activation USE_GITHUB_APP variable name typo, or value is not exactly true The check is vars.USE_GITHUB_APP == 'true' — must be lowercase string
Rate limit errors after migration App installation rate limit (5000 req/hr) shared with other workflows Unlikely with current build cadence; check if other workflows now use the same install

References