DevSecOps Pipeline — Wiring & Interpreting Results

← all weeks · worksheet · readme · slides

<!-- Sandbox/teaching only; for authorized lab use. -->

DevSecOps Pipeline — Wiring & Interpreting Results

OWASP 2025: A09 Security Logging & Alerting Failures, A10 Mishandling of Exceptional Conditions (plus the scanners cover A02/A03).

This folder is a lab template. The workflow does not run from here; you copy it into a repo's .github/workflows/ directory.

1. Wire it in

# From the root of the repo you want to protect:
mkdir -p .github/workflows
cp path/to/labs/week15-devsecops-pipeline/security-ci.yml \
   .github/workflows/security-ci.yml
git add .github/workflows/security-ci.yml
git commit -m "ci: add security gate (Semgrep + Trivy + Gitleaks)"
git push        # the workflow runs on push/PR to main

No secrets are required: Semgrep, Trivy, and Gitleaks all run with the free/public rule sets in this template.

2. What each job does

3. How the gate works (the important part)

Each tool runs twice on purpose:

1. Report step (exit-code: 0 / || true) — produces a SARIF file and

uploads it to the GitHub Security tab. Uses if: always() so the SARIF uploads even when the build is about to fail.

1. Gate step (exit-code: 1, --error) — re-runs and fails the build

if any HIGH/CRITICAL finding (or any secret) exists.

This ordering is deliberate: a single failing scan would abort before the SARIF could upload, hiding the findings. Report-then-gate gives you both the visible results and a red build.

Why not just || true everything? Because then the build never fails and the "gate" is decorative. Real gates must be able to say no.

4. Reading results

• GitHub UI: Security tab -> Code scanning alerts (from the SARIF uploads),

and the Actions run log for the gate step that failed.

• Severity: the template gates on HIGH,CRITICAL. Tune in the workflow

(severity: for Trivy, rulesets for Semgrep) as the class matures.

• Triage: fix, or document a justified, time-boxed exception. Do not

blanket-ignore.

5. "Break the Build" game (see week15 README)

• Blue: keep the gate green by fixing findings.
• Red: open PRs that try to sneak past — e.g. add an old urllib3, a

chmod 777, or a hard-coded token. A correctly-built gate turns the PR red.

6. Run the sample service locally (logging + fail-closed demo)

pip install flask
python sample-service.py
# In another shell:
curl -s -X POST localhost:5001/login -H 'Content-Type: application/json' \
     -d '{"token":"nope"}'                       # -> 401, logs authn_failure
curl -s localhost:5001/admin -H 'Authorization: bob-token'   # -> 403 authz_failure
curl -s localhost:5001/admin -H 'Authorization: alice-token' # -> 200 (admin)

Watch the structured event=... security log lines — those are what a SIEM would alert on (A09). Note that errors deny by default (A10, fail-closed).