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jakman85andClaude Opus 4.8 071123ae43 fix(headlamp): rename OIDC secret keys to OIDC_* so chart args expand

Headlamp OIDC login failed with `unsupported protocol scheme ""`. The
kubernetes-sigs/headlamp chart `envFrom`s the headlamp-oidc Secret verbatim
and renders args like `-oidc-idp-issuer-url=$(OIDC_ISSUER_URL)`, so the Secret
keys must be the exact env var names. The keys were camelCase
(clientID/issuerURL/scopes/callbackURL/clientSecret), following the mistaken
`.example`, so `OIDC_ISSUER_URL` was never defined. Kubernetes left the literal
`$(OIDC_ISSUER_URL)` in the arg and Headlamp's OIDC discovery hit
`Get "$(OIDC_ISSUER_URL)/.well-known/openid-configuration": unsupported
protocol scheme ""`.

Rename the SOPS Secret keys to OIDC_CLIENT_ID / OIDC_CLIENT_SECRET /
OIDC_ISSUER_URL / OIDC_SCOPES / OIDC_CALLBACK_URL (values unchanged, still
SOPS/age-encrypted). Fix the `.example` and README so the correct, load-bearing
key names are documented and the camelCase footgun can't recur.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

2026-08-29 15:09:15 -05:00

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Headlamp — Kubernetes dashboard (Keycloak OIDC + per-user RBAC)

Headlamp is served at https://headlamp.home.keithjackson.dev behind the shared Gateway (wildcard TLS), with native Keycloak OIDC login and per-user RBAC (ADR-0014, docs/15).

How per-user RBAC works (end to end)

A user logs in at Keycloak (homelab realm, headlamp confidential client, auth-code flow).
Headlamp's backend keeps the user's id_token and forwards it as the bearer on every request it proxies to the k3s API server (this is Headlamp's default OIDC behaviour).
The apiserver validates that token — it is configured (infra/ansible roles/k3s_server) with oidc-issuer-url = this realm, oidc-client-id=kubernetes, oidc-username-claim=email, oidc-groups-claim=groups, prefixes oidc:.
RBAC is applied per user via the existing group bindings in ../keycloak/k8s-oidc-rbac.yaml: oidc:platform-admins → cluster-admin, oidc:viewers → view.

So each user gets exactly their own rights — not a shared Headlamp identity. That is why the Headlamp ServiceAccount is not bound to cluster-admin: the chart default clusterRoleBinding.create: true (→ cluster-admin) is overridden to false in helmrelease.yaml. User requests ride the forwarded user token; the SA needs no cluster rights.

The audience nuance (why the client has an audience mapper)

The apiserver only accepts ID tokens whose aud contains kubernetes (oidc-client-id= kubernetes). A plain headlamp client issues aud=[headlamp], which the apiserver would reject. The headlamp client therefore carries an oidc-audience-mapper (see ../keycloak/keycloak-realm-import.yaml) with included.client.audience: kubernetes, so tokens carry aud=[headlamp, kubernetes]:

Headlamp's own verifier accepts it (aud contains headlamp), and
the apiserver accepts it (aud contains kubernetes).

This keeps the apiserver OIDC config untouched (preferred over widening --api-audiences).

Secrets

The confidential client secret lives SOPS-encrypted in ../keycloak/keycloak-realm-clients.sops.yaml (headlamp-client-secret, injected into the realm import via the HEADLAMP_CLIENT_SECRET placeholder) and mirrored in this namespace's headlamp-oidc-credentials.sops.yaml (OIDC_CLIENT_SECRET), which the chart config.oidc.externalSecret envFrom's. Same cross-namespace mirror pattern as grafana/gitea.
Key names are load-bearing. The chart envFroms this Secret verbatim, so its keys become the container env vars referenced by the chart's OIDC args (-oidc-idp-issuer-url=$(OIDC_ISSUER_URL), etc.). They must be exactly OIDC_CLIENT_ID, OIDC_CLIENT_SECRET, OIDC_ISSUER_URL, OIDC_SCOPES (and OIDC_CALLBACK_URL) — not camelCase. A misnamed key leaves $(OIDC_ISSUER_URL) unexpanded and OIDC login fails with unsupported protocol scheme "".

Break-glass

The cert-based admin in the bootstrap kubeconfig is unaffected by any of this and retains full access if Keycloak/OIDC is down — the standard break-glass path.

Files

File	Tier	Purpose
`namespace.yaml`	platform	`headlamp` namespace (`gateway-access=shared`; platform, not app-namespace)
`helmrepository.yaml` / `helmrelease.yaml`	platform	Official `kubernetes-sigs/headlamp` chart + OIDC/RBAC values
`headlamp-oidc-credentials.sops.yaml`	platform	SOPS OIDC config the chart envFrom's (decrypted by the `platform` Flux Kustomization)
`networkpolicy.yaml`	platform	default-deny baseline + Cilium ingress(gateway)/egress(apiserver+Keycloak) allows
`httproute.yaml`	platform-config	Gateway API HTTPRoute for `headlamp.home.keithjackson.dev` (needs Gateway CRDs)

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