pez-infra/.github/workflows/validate-terraform.yml

name: Validate Terraform

on:
  pull_request:
    paths:
      - "terraform/**"
      - ".github/workflows/validate-terraform.yml"

permissions:
  contents: read
  pull-requests: write

# Requires these repository secrets:
#   AGE_SECRET_KEY     — age private key for SOPS decryption
#
# Dependabot PRs run with no access to these secrets and a read-only token,
# so they take a lightweight, secret-free path (init + validate, no plan/
# comment). Provider-version bumps are still resolved and validated.

jobs:
  plan:
    name: tofu plan
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6

      - uses: ./.github/actions/setup-tofu

      # --- Dependabot: secret-free validation -------------------------------
      - name: Validate (no secrets)
        if: github.actor == 'dependabot[bot]'
        working-directory: terraform/
        run: |
          # secrets.yaml is decrypted from SOPS at plan time and can't be
          # produced here, so stub the keys the config reads (kept in sync by
          # deriving them from the actual secrets["..."] references).
          # Stub values must satisfy provider config validators: hcloud
          # requires a 64-char token, and Grafana's fleet_management_auth
          # must look like `username:password`.
          stub64=$(printf 'stub%.0s' {1..16})
          grep -rhoE 'secrets\["[^"]+"\]' . \
            | sed -E 's/.*secrets\["([^"]+)"\].*/\1/' \
            | sort -u \
            | while read -r key; do
                case "$key" in
                  *_auth) echo "$key: \"stub:stub\"" ;;
                  *)      echo "$key: \"$stub64\"" ;;
                esac
              done > secrets.yaml
          tofu init -backend=false
          tofu validate

      # --- Human PRs: full plan against real backend ------------------------
      - name: Decrypt secrets
        if: github.actor != 'dependabot[bot]'
        uses: ./.github/actions/sops-decrypt
        with:
          age-key: ${{ secrets.AGE_SECRET_KEY }}

      - name: Set backend credentials
        if: github.actor != 'dependabot[bot]'
        uses: ./.github/actions/tofu-backend-creds

      # Proxmox (bpg) provider reaches london-a over the tailnet during plan.
      - name: Set up tailnet + SSH
        if: github.actor != 'dependabot[bot]'
        uses: ./.github/actions/setup-tailnet
        with:
          tailscale-client-id: ${{ secrets.TAILSCALE_CLIENT_ID }}
          tailscale-audience: ${{ secrets.TAILSCALE_AUDIENCE }}
          ssh-private-key: ${{ secrets.SSH_PRIVATE_KEY }}

      - name: tofu init
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        run: tofu init

      - name: tofu validate
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        run: tofu validate

      - name: tofu plan
        id: plan
        if: github.actor != 'dependabot[bot]'
        working-directory: terraform/
        continue-on-error: true
        run: |
          set -o pipefail
          tofu plan -no-color 2>&1 | tee plan_output.txt

      - name: Post plan as PR comment
        if: github.actor != 'dependabot[bot]'
        uses: actions/github-script@v9
        with:
          script: |
            const fs = require('fs');
            const raw = fs.readFileSync('terraform/plan_output.txt', 'utf8');
            const filtered = raw.split('\n').filter(l => !l.includes(': Refreshing state...')).join('\n');
            const truncated = filtered.length > 65000
              ? filtered.slice(0, 65000) + '\n\n...(output truncated)'
              : filtered;
            const outcome = '${{ steps.plan.outcome }}';
            const header = outcome === 'failure' ? '## Terraform Plan — FAILED' : '## Terraform Plan';
            const body = `${header}\n\`\`\`\n${truncated}\n\`\`\``;

            const { data: comments } = await github.rest.issues.listComments({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
            });
            const existing = comments.find(c => c.body.startsWith('## Terraform Plan'));
            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body,
              });
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: context.issue.number,
                body,
              });
            }

      - name: Fail if plan failed
        if: github.actor != 'dependabot[bot]' && steps.plan.outcome == 'failure'
        run: exit 1