Files
tenant-registry/internal/authn/authn.go
T
sharangandSharang Parnerkar ce75ed04c2
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RBAC Phase 1: membership authority endpoint + fail-closed API auth (#14)
Implements the model-B2 membership authority (ratified compliance auth design) and inbound token verification.

- GET /v1/users/{id}/memberships: Keycloak supplies user->tenant links + org_roles (attribute projection until the realm migrates to Organizations); registered tenants override status/plan/products from registry tables (source: registry|keycloak). Closes the M5.2-deferred org_roles stub.
- New internal/authn: OIDC discovery + JWKS verification (go-oidc/v3), audience tenant-registry. /healthz + /readyz stay PUBLIC_EXPLICIT; all other routes INTERNAL_SERVICE_ONLY. AUTH_ENABLED=true refuses to start on incomplete config (fail-closed); false (dev default) keeps current behavior.
- Full suite green incl. postgres testcontainers; openapi.yaml updated (contract test passes).

Activation is a separate step (Auth-5): requires the orca-infra env merge and a portal service token (portal currently calls with no auth).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Sharang Parnerkar <30073382+mighty840@users.noreply.github.com>
Reviewed-on: #14
2026-08-24 18:21:46 +00:00

89 lines
3.0 KiB
Go

// Package authn validates Keycloak-issued bearer tokens for the
// tenant-registry API (RBAC rollout Phase 1; fail-closed per the ratified
// compliance auth design, model B2).
//
// The package only verifies — issuer, signature via JWKS, expiry, and
// audience. It deliberately does not authorize: tenant-registry IS the
// membership authority, so its callers are services (INTERNAL_SERVICE_ONLY
// posture) holding client_credentials tokens whose audience includes
// AUTH_EXPECTED_AUDIENCE.
package authn
import (
"context"
"errors"
"fmt"
"strings"
"github.com/coreos/go-oidc/v3/oidc"
)
// ErrNoToken means the Authorization header was absent or not a Bearer
// scheme. Handlers map it to 401 TOKEN_MISSING.
var ErrNoToken = errors.New("authorization header missing or not Bearer")
// Principal is the verified caller identity, placed in the request context
// so handlers (and, later, audit writes) can attribute actions.
type Principal struct {
Subject string // JWT sub — the Keycloak user or service-account id
ClientID string // JWT azp — which OAuth client obtained the token
Issuer string
}
type ctxKey struct{}
// WithPrincipal returns ctx carrying p.
func WithPrincipal(ctx context.Context, p *Principal) context.Context {
return context.WithValue(ctx, ctxKey{}, p)
}
// PrincipalFrom extracts the verified principal, if any.
func PrincipalFrom(ctx context.Context) (*Principal, bool) {
p, ok := ctx.Value(ctxKey{}).(*Principal)
return p, ok
}
// Verifier checks bearer tokens against one issuer + audience. A nil
// *Verifier means auth is disabled (AUTH_ENABLED=false) and the server
// passes requests through unauthenticated.
type Verifier struct {
issuer string
verifier *oidc.IDTokenVerifier
}
// New performs OIDC discovery against issuer and prepares JWKS-backed
// verification. Callers must treat an error as fatal when AUTH_ENABLED=true
// (AUTH_CONFIG_INCOMPLETE — refuse to start, never fall open).
func New(ctx context.Context, issuer, audience string) (*Verifier, error) {
if issuer == "" || audience == "" {
return nil, errors.New("issuer and audience are required")
}
provider, err := oidc.NewProvider(ctx, issuer)
if err != nil {
return nil, fmt.Errorf("oidc discovery for %s: %w", issuer, err)
}
return &Verifier{
issuer: issuer,
verifier: provider.Verifier(&oidc.Config{ClientID: audience}),
}, nil
}
// Verify checks the raw Authorization header value and returns the caller
// principal. Signature, issuer, expiry, and audience are all enforced by
// the underlying oidc verifier.
func (v *Verifier) Verify(ctx context.Context, authorization string) (*Principal, error) {
raw, ok := strings.CutPrefix(authorization, "Bearer ")
if !ok || strings.TrimSpace(raw) == "" {
return nil, ErrNoToken
}
tok, err := v.verifier.Verify(ctx, strings.TrimSpace(raw))
if err != nil {
return nil, err
}
var claims struct {
Azp string `json:"azp"`
}
_ = tok.Claims(&claims) // azp is informational; absence is not an error
return &Principal{Subject: tok.Subject, ClientID: claims.Azp, Issuer: tok.Issuer}, nil
}