Keys never live in a repo: an ignore list and a scanner that actually looks

.github/workflows/gitleaks.yml

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+name: gitleaks
+
+# Secret scanning that covers the ways a secret actually gets in.
+#
+# WHY THIS EXISTS. On 2026-07-30 a VPN profile with an unencrypted private key
+# was found in the planning repo, committed 2026-07-01 and readable by five
+# people for 29 days. Secret scanning did not miss it — it never looked. Three
+# holes, all closed here:
+#
+#   1. WRONG REPO — scanning ran on 3 of 14 repos. This workflow goes on every
+#      repo in the org, public ones included.
+#   2. WRONG TRIGGER — it fired on pull requests only, and that repo pushes
+#      straight to main. This fires on pushes too, on every branch.
+#   3. WRONG SCOPE — it read only the diff of a pull request, so anything that
+#      arrived another way stayed invisible. The weekly run reads the ENTIRE
+#      history, so a secret that slipped in before this workflow existed still
+#      gets found.
+#
+# FAIL-CLOSED, deliberately. A hit fails the job, and so does an error running
+# the scanner. A scan that could not run must never report success — that is
+# the same trap as a test that passes while measuring nothing.
+#
+# ON A HIT: the credential is compromised. Remove it, ROTATE it (git history
+# keeps the old value), confirm it is covered by .gitignore. Rewriting history
+# alone does not make a leaked key safe — only rotation does.
+
+on:
+  pull_request:
+  push:
+  schedule:
+    - cron: '23 6 * * 1'   # Mondays 06:23 UTC — the full-history sweep
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: gitleaks-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  scan:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # every commit — the scheduled sweep reads the whole history, and a
+          # shallow clone would silently scan almost nothing
+          fetch-depth: 0
+
+      - name: Scan for secrets
+        env:
+          EVENT: ${{ github.event_name }}
+          PR_BASE: ${{ github.event.pull_request.base.sha }}
+          PR_HEAD: ${{ github.event.pull_request.head.sha }}
+          PUSH_BEFORE: ${{ github.event.before }}
+          PUSH_AFTER: ${{ github.sha }}
+        run: |
+          set -euo pipefail
+          V=8.18.4
+          curl -sSfL "https://github.com/gitleaks/gitleaks/releases/download/v${V}/gitleaks_${V}_linux_x64.tar.gz" \
+            | tar -xz -C /tmp gitleaks
+
+          # Pick the range. Anything unusual — a brand-new branch (all-zero
+          # "before"), a scheduled run, a manual run — falls through to the
+          # whole history rather than skipping the scan.
+          RANGE=""
+          case "$EVENT" in
+            pull_request) RANGE="${PR_BASE}..${PR_HEAD}" ;;
+            push)         RANGE="${PUSH_BEFORE}..${PUSH_AFTER}" ;;
+          esac
+          if printf '%s' "$RANGE" | grep -qE '^0{40}\.\.|\.\.0{40}$|^\.\.|^$'; then
+            RANGE=""
+          fi
+
+          if [ -n "$RANGE" ]; then
+            echo "scanning range $RANGE"
+            /tmp/gitleaks detect --source=. --redact --log-opts="$RANGE"
+          else
+            echo "scanning the ENTIRE history"
+            /tmp/gitleaks detect --source=. --redact
+          fi
+
+      - name: What to do if that failed
+        if: failure()
+        run: |
+          echo "::error::A secret was found, or the scan could not run. Either way this does not merge."
+          echo "If a credential was found: it is compromised. Remove it, ROTATE it (git history keeps the old value),"
+          echo "and confirm .gitignore covers it. Rewriting history alone does NOT make a leaked key safe."
+          exit 1

.gitignore

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+
+# ─────────────────────────────────────────────────────────────────────────────
+# CREDENTIALS NEVER LIVE IN A REPO.
+#
+# Added org-wide 2026-07-30. A VPN connection profile carrying an unencrypted
+# private key had been sitting in the planning repo since 2026-07-01 — pushed
+# as a side effect of a folder move, not a decision, and readable by five
+# people for 29 days. The whole VPN trust chain was burned the day it was found.
+#
+# It got in because nothing scanned that path: secret scanning ran on only 3 of
+# 14 repos, fired on pull requests only, and read just the diff. All three holes
+# are closed by .github/workflows/gitleaks.yml, added in the same change as
+# this block. This list is the second layer — it stops the file being staged in
+# the first place.
+#
+# This is a PREVENTIVE list. It does not untrack anything already committed;
+# nothing existing is removed by adding it.
+# ─────────────────────────────────────────────────────────────────────────────
+
+# VPN / connection profiles
+*.ovpn
+*.tblk
+*.mobileconfig
+
+# keys and certificates
+*.pem
+*.key
+*.p8
+*.p12
+*.pfx
+*.jks
+*.keystore
+*.crt
+*.cer
+*.der
+*.asc
+*.gpg
+*.kdbx
+*_rsa
+*_dsa
+*_ecdsa
+*_ed25519
+*.ppk
+
+# environment files — .env.example stays, it holds names not values
+.env
+.env.*
+!.env.example
+!.env.sample
+!.env.template
+
+# cloud + service credentials
+.aws/credentials
+credentials.json
+service-account*.json
+gcloud-service-key.json
+*-serviceaccount.json
+.npmrc
+.pypirc
+.netrc
+kubeconfig
+*.kubeconfig
+terraform.tfvars
+*.auto.tfvars
+.pulumi/credentials.json