TowerGit ↔ CI/CD Pipeline: Least‑Privilege Authentication vs Expired Credentials

Answer

TowerGit does not currently provide automated expiration checks or built‑in alerts for OAuth/PAT tokens, and there is no public roadmap indicating when such features will be added. Therefore, pipelines must validate token validity themselves and rely on external secret‑rotation practices to avoid silent success when a token is revoked or expired.

Confirmed facts

• TowerGit OAuth scopes (read_repository, write_repository, admin_repository) enforce least‑privilege access when the token is presented.
• Personal Access Tokens (PATs) remain valid until explicitly revoked; the service does not reject a request based on an embedded timestamp.
• No native webhook or notification mechanism exists for token expiry or revocation.

Likely explanation / recommended pattern

1. Pre‑job token introspection: At the start of each CI/CD job, call a TowerGit endpoint that requires authentication (e.g., GET https://api.towergit.com/user) with the token in the Authorization: Bearer $TOKEN header. Treat any HTTP 401/403 response as proof that the token is no longer valid and fail the job immediately.
2. Short‑lived credentials: Where possible, replace static PATs with OIDC‑based short‑lived tokens issued by your CI platform (e.g., GitHub Actions OIDC, GitLab CI JWT). TowerGit can be configured to trust the CI provider’s identity provider, eliminating the need to store any secret.
3. Secret rotation schedule: If you must continue using PATs, automate rotation (e.g., weekly) and store the new value in a secret manager. Notify the pipeline via the secret manager’s update event so the job picks up the fresh token on the next run.
4. Monitoring & alerting: Set up a scheduled job (outside the pipeline) that periodically introspects the stored PAT and raises an alert (email, Slack, PagerDuty) when the introspection call returns 401/403. This gives operators visibility before a pipeline silently succeeds with a stale token.

Steps for this case (using a PAT)

1. Store the TowerGit PAT as a masked secret (e.g., TOWERGIT_PAT) in your CI secret store.
2. Add a validation step before any Git operation:

# Example for a Bash‑based CI step
curl -s -o /dev/null -w "%{http_code}" \
  -H "Authorization: Bearer $TOWERGIT_PAT" \
  https://api.towergit.com/user
if [ "$response" -ne 200 ]; then
  echo "❌ TowerGit token invalid or expired"
  exit 1
fi

1. Proceed with the rest of the pipeline (clone, build, deploy) knowing the token is currently valid.
2. Rotate the PAT according to your organization’s policy and update the secret store.

Missing diagnostic detail

To refine the validation step, we need to know whether TowerGit’s API response includes an explicit expiration field (e.g., expires_at or an exp claim) that could be checked without relying on a 401/403. If such a field exists, the pipeline could compare it to the current time and fail earlier; otherwise, the introspection‑call approach is the only reliable method.