docs(monitoring): add OIDC authentication guide for Grafana

content/en/docs/next/operations/services/monitoring/oidc-authentication.md

@@ -0,0 +1,158 @@
+---
+title: "OIDC authentication for Grafana"
+linkTitle: "OIDC authentication"
+description: "Give tenant users per-identity Grafana access with per-instance audience isolation and tenant-membership gating."
+weight: 5
+---
+
+Cozystack Grafana instances can authenticate users through OIDC instead of the shared `admin_user` / `admin_password` Secret. Each user then has their own identity, per-user audit, and a role that can be revoked by removing them from `spec.oidc.users` on the `Monitoring` CR.
+
+The identity model is deliberately **per-instance** rather than per-tenant: each Monitoring release (per-tenant `monitoring`, plus the platform's `monitoring-system`) gets its own OIDC audience, and a token minted for instance A is rejected by instance B's Grafana. Cross-tenant sign-in is additionally blocked by a `allowed_groups` gate on the release's namespace-scoped `<ns>-{view,use,admin,super-admin}` groups (chart-owned in the tenant chart; the platform-managed `groups` scope in the `cozy` realm makes them visible on every token). The full rationale is in the [design proposal](https://github.com/cozystack/community/pull/24). The tenant kube-apiserver's Phase 1 ([cozystack/cozystack#3044](https://github.com/cozystack/cozystack/pull/3044)) uses the same shape; this Grafana integration is the Phase-1 follow-up called out in that PR's body.
+
+{{% alert color="info" %}}
+The `grafana-admin-password` Secret in the release namespace stays available as a break-glass path regardless of whether OIDC is enabled. `disable_login_form` is not flipped by the selector.
+{{% /alert %}}
+
+## Modes
+
+`spec.oidc.mode` picks the identity source on the `Monitoring` CR:
+
+- **`None`** — the default. No OIDC; only the `admin_user` / `admin_password` Secret works. Existing instances render identically to before.
+- **`System`** — trust the platform `cozy` Keycloak realm via a per-instance confidential client and audience binding. Users are the ones a Cozystack platform admin already provisioned in `cozy`; the tenant does not manage a directory of its own.
+- **`CustomConfig`** — trust a tenant-supplied issuer directly (BYO IdP: Okta, Auth0, a customer's own Keycloak). `cozy` is not in the path.
+
+## Enable OIDC — `System` mode
+
+```yaml
+apiVersion: apps.cozystack.io/v1alpha1
+kind: Monitoring
+metadata:
+  name: monitoring
+  namespace: tenant-acme
+spec:
+  oidc:
+    mode: System
+    users:
+      - email: alice@acme.example
+        role: Admin
+      - email: bob@acme.example
+        role: Editor
+      - email: carol@acme.example
+        role: Viewer
+  # ...
+```
+
+Cozystack provisions:
+
+- A per-instance **`KeycloakClient`** in the `cozy` realm with `clientId` set to `<namespace>-<release>` (for the CR above: `tenant-acme-monitoring-system`). Confidential (`clientAuthenticatorType: client-secret`), `secret` sourced from a chart-owned Kubernetes Secret. `redirectUris` locked to `https://grafana.<host>/login/generic_oauth`.
+- A per-instance **`KeycloakClientScope`** whose audience mapper pins the token's `aud` claim to that same `clientId` — the isolation primitive.
+- A persistent Kubernetes **Secret** carrying the confidential `client-secret` (random on first install, preserved on upgrades).
+- A chart-owned **users-reconcile Job** (`<release>-oidc-users`) that syncs `spec.oidc.users[]` into the Grafana instance on every reconcile: creates missing Grafana accounts, patches roles, and prunes stale org members. Runs as a post-install / post-upgrade hook when `users[]` is non-empty; omitted otherwise (BYO-IdP-friendly).
+- The Grafana CR's **`spec.config.auth.generic_oauth`** section wired to the cozy realm issuer, per-instance audience scope, and the tenant-membership gate:
+
+  ```
+  allowed_groups        = <namespace>-view <namespace>-use <namespace>-admin <namespace>-super-admin
+  groups_attribute_path = groups
+  ```
+
+  `groups_attribute_path` is REQUIRED alongside `allowed_groups` on Grafana v11.x+: without it Grafana leaves the extracted `user.Groups` slice empty regardless of what the userinfo endpoint returns, and the gate rejects every login with "user not a member of one of the required groups" even when the token carries the correct claim. The JMESPath expression `groups` reads the top-level `groups` array from userinfo — the shape Keycloak's `oidc-group-membership-mapper` emits.
+
+  When `spec.oidc.users[]` is non-empty the chart additionally forces:
+
+  ```
+  skip_org_role_sync                = true
+  oauth_allow_insecure_email_lookup = true
+  allow_sign_up                     = false
+  ```
+
+  `skip_org_role_sync=true` keeps a login from overwriting the users-Job's role assignments; `oauth_allow_insecure_email_lookup=true` lets Grafana attach the OIDC identity to the pre-provisioned local account by email; `allow_sign_up=false` is the isolation lever — without it, Grafana's default `allow_sign_up=true` combined with `skip_org_role_sync=true` would mint a Viewer account for every `cozy`-realm identity that hits the login flow.
+
+Server-level `GrafanaAdmin` promotion is opt-in via `spec.oidc.grafanaAdmin: true` — the chart then sets `allow_assign_grafana_admin: true` on the rendered `[auth.generic_oauth]` block. The platform bundle flips this on for the platform Grafana release (`monitoring-system` in `cozy-monitoring`); tenant Grafana releases inherit the chart default `false` and stay at org-level Admin.
+
+### Prerequisite
+
+`System` mode requires the platform-level OIDC feature (`authentication.oidc.enabled` at the Cozystack platform values). If the flag is off, the chart hard-fails the render with a clear message. Ask a Cozystack platform admin to enable it, or use `CustomConfig`.
+
+## Enable OIDC — `CustomConfig` mode
+
+Bring your own issuer. Two supply paths, **mutually exclusive**:
+
+```yaml
+spec:
+  oidc:
+    mode: CustomConfig
+    customConfig:
+      config:
+        client_id: my-grafana
+        client_secret: xxxxxxxx
+        auth_url: https://idp.acme.example/protocol/openid-connect/auth
+        token_url: https://idp.acme.example/protocol/openid-connect/token
+        api_url: https://idp.acme.example/protocol/openid-connect/userinfo
+        scopes: openid email profile groups
+    users:
+      - email: alice@acme.example
+        role: Admin
+```
+
+…or via a pre-existing Secret in the tenant namespace holding a ready-made `[auth.generic_oauth]` ini fragment in the `auth.ini` key:
+
+```yaml
+spec:
+  oidc:
+    mode: CustomConfig
+    customConfig:
+      secretRef:
+        name: acme-byo-grafana-auth
+```
+
+Setting both `config` and `secretRef.name` (or neither) fails the render. In `CustomConfig` mode no Keycloak objects are provisioned in `cozy`; the Grafana instance trusts the operator-supplied issuer directly.
+
+The `secretRef` path is authoritative — the chart does not overlay any keys onto the operator-supplied ini fragment. If you use `secretRef`, `spec.oidc.users[]` MUST be empty (the chart fails the render otherwise) because the users-Job cannot reason about a config it cannot see.
+
+The `inline config` path merges the operator's map on top of the chart-forced users-map contract (`skip_org_role_sync=true`, `oauth_allow_insecure_email_lookup=true`, `allow_sign_up=false`) when `users[]` is non-empty. If your BYO IdP does not emit `groups` in the shape Grafana expects, add `groups_attribute_path` to your inline map to point at the right JMESPath.
+
+## Assigning roles
+
+Roles are driven by **`spec.oidc.users[]`**, not by group membership: each entry has an `email` (matched against the OIDC `email` claim on login) and a `role` (Grafana org-level: `Admin`, `Editor`, or `Viewer`). The users-Job creates or updates the local Grafana account on every reconcile and prunes stale members. Removing a user from the list demotes them (users-Job deletes the account) on the next chart apply; adding a user re-provisions them.
+
+Login authorization is separate: the token owner MUST be a member of one of the release's tenant-scoped `cozy`-realm groups (`<namespace>-view`, `<namespace>-use`, `<namespace>-admin`, `<namespace>-super-admin`) for `allowed_groups` to accept the login. That gate is unconditional in `System` mode, independent of `users[]`.
+
+Add a user to the appropriate tenant-scoped group in `cozy` — via the Keycloak UI or with a `KeycloakRealmUser` CR:
+
+```yaml
+apiVersion: v1.edp.epam.com/v1
+kind: KeycloakRealmUser
+metadata:
+  name: alice-acme
+  namespace: cozy-keycloak
+spec:
+  realm: cozy
+  username: alice@acme.example
+  email: alice@acme.example
+  emailVerified: true
+  password: "…"
+  groups:
+    - tenant-acme-admin
+```
+
+## Sign in
+
+Open `https://grafana.<host>` and press "Sign in with Keycloak" under the login form. Grafana runs the OAuth Authorization Code flow against `cozy`, receives a token whose `aud` matches this Monitoring instance's clientId, checks the `groups` claim against `allowed_groups`, then looks up the pre-provisioned Grafana account by email and grants the users-Job-assigned role.
+
+The `admin_user` / `admin_password` field on the form stays wired to `grafana-admin-password` and continues to work.
+
+## Prerequisites and gotchas
+
+- **`emailVerified: true` on Keycloak users.** Phase 1 does not add a `claimValidationRules` entry — so `email_verified` is not chart-enforced. Set `emailVerified: true` on the `KeycloakRealmUser` (or complete the email-verify flow through the Keycloak UI) so the identity holding a given email is guaranteed authentic. The `cozy` realm's default `duplicateEmails: false` prevents a second account from claiming an already-registered address. CEL `claimValidationRules` to make this a hard gate is a follow-up hardening path.
+- **`groups_attribute_path` is not optional on Grafana v11.x+.** The chart wires it automatically for `System` mode; in `CustomConfig` inline the operator must add it explicitly (`groups_attribute_path: groups`) if their IdP emits a top-level `groups` array. Otherwise `allowed_groups` becomes a silent no-op and every login fails.
+- **BYO issuer with a self-signed CA.** In `CustomConfig` mode the `secretRef` path is the way to ship a CA bundle alongside the `[auth.generic_oauth]` block — you package `auth.ini` and any `ca-cert` files into the Secret and mount both under `/etc/grafana/oidc`.
+- **`admin_user` stays a break-glass path.** Even under `mode: System` the login form and the `grafana-admin-password` Secret remain wired. Locking the form off is a follow-up hardening.
+- **Mode toggle drops the users-Job's local accounts.** Flipping `spec.oidc.mode` from `System` to `None` prunes every user the users-Job provisioned (the accounts are ephemeral shadows of `spec.oidc.users[]`). Any dashboards those users starred / owned move to their original creators; the local passwords / API keys go away. Flipping back re-provisions them empty. Treat mode toggle like an admin-Secret rotation.
+
+## What's out of scope for this feature
+
+- **Per-tenant Keycloak realms.** Managed multi-tenant identity is a separate proposal, evaluated against Keycloak Organizations. Track it in the [community proposal](https://github.com/cozystack/community/pull/24).
+- **Federating an external IdP into the platform `cozy` realm.** BYO-for-Cozystack-itself is a distinct problem — this feature is BYO-for-a-managed-service.
+- **Full-logout through Keycloak's end-session endpoint.** Native `auth.generic_oauth` covers the OAuth part; `backend-logout-url` wiring is a follow-up.
+- **CEL `claimValidationRules` for `email_verified`.** Explicit-gate hardening; not required for Phase 1 given the layered guarantees above.
+- **Role granularity beyond Admin/Editor/Viewer.** Grafana org roles are the assignment surface; team memberships / dashboard-level permissions stay out-of-band.