Merge pull request 'feat(ci): the pipeline is the approver' (#17) from feat/ci-is-the-approver into main

Reviewed-on: #17
Reviewed-by: Keith Jackson <[email protected]>

ci/Makefile

@@ -35,6 +35,9 @@ decisions-log: ## handoff log: DECISIONS-LOG.md frozen, decisions/ entries well-
 l1: ## L1 rendering checks (no cluster; live now)
 	@"$(CI_DIR)l1.sh"
 
+approval-policy: ## CI is the approver; sensitive paths still need a human (needs PR_NUMBER + token)
+	@./approval-policy.sh
+
 gitea-settings: ## Gitea branch protection + runners match infra/gitea/expected-branch-protection.json (SKIPS w/o GITEA_SETTINGS_TOKEN)
 	@./gitea-settings.sh
 

ci/approval-policy.sh

@@ -0,0 +1,117 @@
+#!/usr/bin/env bash
+# ci/approval-policy.sh — the CI/CD pipeline is the approver, EXCEPT for changes that alter
+# what the pipeline verifies or the security posture it rests on.
+#
+# THE POLICY, and why it is shaped this way.
+#
+# Operator intent (2026-09-29): "CI/CD pipeline is the end-all-be-all for approval. If the CI
+# pipeline is not good enough to be trusted for this, then it is not good enough to do its
+# intended job and needs to be improved. Manual approvers should only be for architecturally or
+# security relevant changes -- which is essentially the CI pipeline itself and kyverno policies."
+#
+# So `required_approvals` on the branch drops to 0 and the GATE decides. That is a real transfer
+# of authority, and it has exactly one hole: **a change to the gate cannot be gated by the gate.**
+# A PR that weakens a check would be approved by the weakened check. The same applies to the
+# admission policies, the Flux wiring that decides what reconciles, the SOPS recipients, and the
+# RBAC. Those are the "architecturally or security relevant" set, and this stage is what still
+# requires a human for them.
+#
+# The list is data, not code: infra/gitea/approval-policy.json, with a stated reason per entry so
+# it stays reviewable. Changing that list is itself a sensitive change (infra/gitea/**), so the
+# policy cannot be widened without a human.
+#
+# FAIL-CLOSED, DELIBERATELY DIFFERENT FROM gitea-settings.sh. That stage skips when its token is
+# missing, because an unwired credential blocking every PR is a lock-out. Here the reverse is
+# true: if this cannot evaluate, an unreviewed change to the gate itself could merge. A skip is a
+# BYPASS, not a gap. So: cannot determine -> BLOCK.
+#
+# EXIT CODES
+#   0  no sensitive paths touched (gate alone is sufficient), OR sensitive paths touched and a
+#      non-author APPROVED review is present
+#   1  sensitive paths touched without such a review, OR the policy could not be evaluated
+set -euo pipefail
+CI_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+REPO_ROOT="$(cd "${CI_DIR}/.." && pwd)"
+# shellcheck disable=SC1091
+source "${CI_DIR}/lib.sh"
+
+log "Stage: approval policy (CI approves; humans approve changes to CI)"
+
+DECL="${REPO_ROOT}/infra/gitea/approval-policy.json"
+[ -f "$DECL" ] || die "approval policy declaration missing: ${DECL}"
+require_tool jq
+require_tool python3
+
+# Not a PR -> nothing to gate. A push to main is already merged, and direct pushes are refused
+# by branch protection, so this is genuinely not-applicable rather than a skipped check.
+EVENT="${GITHUB_EVENT_NAME:-${EVENT_NAME:-}}"
+PR="${PR_NUMBER:-}"
+if [ "$EVENT" != "pull_request" ] || [ -z "$PR" ] || [ "$PR" = "null" ]; then
+  ok "not a pull_request event (event='${EVENT:-none}') — approval policy N/A"
+  exit 0
+fi
+
+GITEA_URL="${GITEA_URL:-https://gitea.home.keithjackson.dev}"
+GITEA_REPO="${GITEA_REPO:-Home-Network/home-network-k3s-impl}"
+TOKEN="${SETTINGS_API_TOKEN:-${GITEA_SETTINGS_TOKEN:-}}"
+if [ -z "$TOKEN" ]; then
+  err "no SETTINGS_API_TOKEN — cannot read this PR's changed files or its reviews."
+  err "  BLOCKING. A skip here would let an unreviewed change to the gate itself merge."
+  summary "- approval-policy: **BLOCKED — cannot evaluate** (no token; a skip here is a bypass)"
+  exit 1
+fi
+api() { curl -sS --max-time 20 -H "Authorization: token ${TOKEN}" "$@"; }
+
+FILES_JSON="$(api "${GITEA_URL}/api/v1/repos/${GITEA_REPO}/pulls/${PR}/files?limit=1000" || true)"
+PR_JSON="$(api "${GITEA_URL}/api/v1/repos/${GITEA_REPO}/pulls/${PR}" || true)"
+REVIEWS_JSON="$(api "${GITEA_URL}/api/v1/repos/${GITEA_REPO}/pulls/${PR}/reviews" || true)"
+for v in FILES_JSON PR_JSON REVIEWS_JSON; do
+  jq -e . >/dev/null 2>&1 <<<"${!v}" || {
+    err "could not read ${v} from Gitea for PR #${PR} — BLOCKING rather than assuming."
+    summary "- approval-policy: **BLOCKED — Gitea unreadable**"
+    exit 1; }
+done
+
+AUTHOR="$(jq -r '.user.login // empty' <<<"$PR_JSON")"
+[ -n "$AUTHOR" ] || { err "could not determine PR author — BLOCKING"; exit 1; }
+
+# NOTE: the PR file list goes in via an ENV VAR, not a second stdin redirect. `python3 - <<EOF`
+# already consumes stdin for the script; adding `<<<"$json"` silently wins and the script body is
+# never read. Caught before shipping, by running it.
+SENSITIVE="$(FILES_JSON="$FILES_JSON" DECL="$DECL" python3 -c '
+import json, os, fnmatch
+decl = json.load(open(os.environ["DECL"]))
+files = [f.get("filename", "") for f in json.loads(os.environ["FILES_JSON"])]
+pats = decl["sensitive_paths"]
+hits = sorted({f for f in files for p in pats
+               if fnmatch.fnmatch(f, p) or (p.endswith("/**") and f.startswith(p[:-2]))})
+print("\n".join(hits))
+')"
+
+if [ -z "$SENSITIVE" ]; then
+  ok "no architecturally/security-relevant paths touched — the GATE is the approver."
+  summary "- approval-policy: **green** (CI approves; no sensitive paths touched)"
+  exit 0
+fi
+
+echo "  sensitive paths touched:" >&2
+printf '    %s\n' $SENSITIVE >&2
+
+APPROVER="$(jq -r --arg a "$AUTHOR" \
+  '[.[] | select(.state == "APPROVED") | select(.user.login != $a) | .user.login] | first // empty' \
+  <<<"$REVIEWS_JSON")"
+
+if [ -n "$APPROVER" ]; then
+  ok "approved by '${APPROVER}' (author '${AUTHOR}') — sensitive change is human-reviewed."
+  summary "- approval-policy: **green** (sensitive paths approved by \`${APPROVER}\`)"
+  exit 0
+fi
+
+err "This PR changes the pipeline or the security posture it rests on, and has NO approving"
+err "  review from anyone other than its author ('${AUTHOR}')."
+err "  A change to the gate cannot be gated by the gate — that is the one thing CI cannot"
+err "  honestly approve for itself. Get a human review, or move the change out of:"
+printf '    %s\n' $SENSITIVE >&2
+err "  The list lives in infra/gitea/approval-policy.json, with a reason per entry."
+summary "- approval-policy: **BLOCKED — sensitive paths need a non-author approval**"
+exit 1

ci/gate.sh

@@ -113,6 +113,7 @@ run_stage lint          "${CI_DIR}/lint.sh"
 run_stage l0            "${CI_DIR}/l0.sh"
 run_stage render-golden "${CI_DIR}/render-golden.sh"
 run_stage l1            "${CI_DIR}/l1.sh"
+run_stage approval-policy "${CI_DIR}/approval-policy.sh"
 run_stage gitea-settings "${CI_DIR}/gitea-settings.sh"
 run_stage conformance   "${CI_DIR}/conformance.sh"
 
@@ -190,6 +191,20 @@ case "${OUTCOME[spec-immutability]}" in
   pass) ok   "spec-immutability: green" ;;
 esac
 
+# approval-policy: the branch requires NO human approvals (required_approvals: 0) -- the GATE
+# is the approver, per operator intent. This stage is the single exception: a change to the
+# pipeline itself, the admission policies, the Flux wiring, the SOPS recipients or the RBAC
+# cannot honestly be approved BY the thing it changes, so those paths still need a human.
+#
+# It never SKIPS -- it exits 0 or 1 only, and blocks when it cannot evaluate. That is the
+# opposite of gitea-settings' tolerance and it is deliberate: there, a missing credential is a
+# lock-out; here, a missing credential would let an unreviewed change to the gate merge.
+case "${OUTCOME[approval-policy]}" in
+  fail) err "approval-policy: a sensitive change lacks a non-author approval -> blocks merge"; BLOCK=1 ;;
+  skip) err "approval-policy: did not run -- it is fail-closed by design, so treat as a block"; BLOCK=1 ;;
+  pass) ok  "approval-policy: green" ;;
+esac
+
 # gitea-settings: the ONLY check that can see Gitea's own database (branch protection +
 # runner registration). A FAIL is real drift and always blocks -- that is the whole point.
 # A SKIP means no token or unreachable Gitea, which is an UNWIRED CREDENTIAL, not a defect