signing-service: Pocket-ID JWKS + K8s TokenReview + OPA (DEV-609)
Wires the signing-service's production path for ProofedMesh Phase 1:
the service now performs a double identity check (Pocket-ID OIDC JWT
+ K8s ServiceAccount TokenReview), reconciles both against the
trust-api `agents` registry, and asks an OPA/Rego policy whether the
caller may sign with the requested key_ref.
Code
- internal/token/pocket_id.go: OIDC-Discovery-backed JWKS validator
with automatic kid rotation (coreos/go-oidc).
- internal/token/k8s_tokenreview.go: hand-rolled TokenReview client;
reads X-Workload-Token, posts to authentication.k8s.io/v1 via the
pod's in-cluster SA token + CA.
- internal/registry: Postgres resolver for the agents table +
in-memory Static resolver for tests.
- internal/policy/opa.go: OPA/rego StructuredDecider; input carries
both lookups so the policy can enforce identity consistency AND
the key_ref ↔ role mapping.
- internal/httpapi/sign.go: new structured flow when
Validator+TokenReviewer+Registry+StructuredPolicy are all wired;
dev path (static bearers + AllowAll) remains intact.
- cmd/signing-service/main.go: -pocket-id-issuer,
-pocket-id-audience, -k8s-tokenreview, -registry-dsn,
-policy-bundle flags.
Policy
- policies/sinks/signing_service.rego: identities_agree +
key_ref_matches_role rules; agent → key_ref prefix map covers
approval-service, testagent-transform, dummy-sink.
Deploy
- deploy/signing-service/01-rbac.yaml: ClusterRole with
tokenreviews.create + binding to the signing-service SA.
- deploy/signing-service/20-deployment.yaml: adds POCKET_ID_ISSUER,
POCKET_ID_AUDIENCE, TRUST_PG_DSN env, projected SA token volume,
OPA policy ConfigMap mount, structured flags.
- deploy/signing-service/00-serviceaccount.yaml: disables default
auto-mount; a projected volume is used.
- deploy/signing-service/README.md: documents prod flags +
ConfigMap generation.
Tests
- httptest-mock Pocket-ID (OIDC discovery + JWKS, kid rotation),
StaticTokenReviewer fake, Static registry, real Rego policy.
- Happy paths: Approval-Service → trust-api/approval-signer-2026-q4;
testagent-transform → trust-api/agent-testagent-transform-2026-q4.
- Denies: registry mismatch, wrong key_ref for role, missing /
bad workload token, bad Pocket-ID token, kid rotation.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
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