authentik: add Grafana OAuth2/OIDC provider + application

Adds an OIDC provider + application so the in-cluster Grafana
(grafana.k8s.syd1.au.unkin.net) can authenticate users against Authentik.

Extends the oauth2 module so provider config stays declarative and
secret-free:
- Resolve authorization/invalidation flows by slug (data.authentik_flow)
  and scope mappings by managed identifier
  (data.authentik_property_mapping_provider_scope).
- Read client_secret from Vault kv-v2 (data.vault_kv_secret_v2) instead of
  committing it; adds the hashicorp/vault provider (auth via VAULT_ADDR/
  VAULT_TOKEN from the Makefile).
- Support allowed_redirect_uris on the oauth2 provider.

config/providers_oauth2/grafana.yaml wires client_id `grafana`, the
openid/email/profile scopes, the login/generic_oauth redirect URI, and
points client_secret at kv/kubernetes/namespace/grafana/default/oauth-credentials.

config/providers_oauth2/grafana.yaml

@@ -0,0 +1,17 @@
+# OAuth2/OIDC provider + application for the in-cluster Grafana
+# (grafana.k8s.syd1.au.unkin.net). client_secret is read from Vault, not committed.
+name: Grafana
+authorization_flow: default-provider-authorization-implicit-consent
+invalidation_flow: default-provider-invalidation-flow
+client_type: confidential
+client_id: grafana
+client_secret_vault:
+  mount: kv
+  path: kubernetes/namespace/grafana/default/oauth-credentials
+scope_mappings:
+  - goauthentik.io/providers/oauth2/scope-openid
+  - goauthentik.io/providers/oauth2/scope-email
+  - goauthentik.io/providers/oauth2/scope-profile
+redirect_uris:
+  - matching_mode: strict
+    url: https://grafana.k8s.syd1.au.unkin.net/login/generic_oauth

environments/root.hcl

@@ -7,6 +7,10 @@ provider "authentik" {
   token = var.authentik_token
 }
 
+# Reads client secrets seeded in Vault (kv-v2). Auth via VAULT_ADDR + VAULT_TOKEN
+# from the environment (set by the Makefile vault_env helper).
+provider "vault" {}
+
 variable "authentik_token" {
   type      = string
   sensitive = true
@@ -26,6 +30,10 @@ terraform {
       source  = "goauthentik/authentik"
       version = "2026.5.0"
     }
+    vault = {
+      source  = "hashicorp/vault"
+      version = ">= 4.0.0"
+    }
   }
 }
 EOF

modules/authentik/.terraform.lock.hcl

@@ -21,3 +21,26 @@ provider "registry.opentofu.org/goauthentik/authentik" {
     "zh:eb9c1fd3020cf61e9b7a6a38d2965f4b521495a9928705e963459a4af857f97d",
   ]
 }
+
+provider "registry.opentofu.org/hashicorp/vault" {
+  version     = "5.10.1"
+  constraints = ">= 4.0.0"
+  hashes = [
+    "h1:wo5cTkl/1nlxMfdn1yEDIHNoRLMczuK6COH2Id4/zeY=",
+    "zh:0abf976c01f0c0732d0ccc6481e52008be5ee9c8e3d9b5eba0573c640fcf7019",
+    "zh:2aff4d7ee7ba9eb3de2cd5cda16ba92b4ec7a2b43232aec180984241a323b216",
+    "zh:2cc186fd0bfc44e100a22b0b40ae8ddcd0ec210a53c1da65d310ee758b1d2b08",
+    "zh:3f8fb8594736b34af4b26437dd4df4dd4042ad4905223995cfebb8a1f10682ec",
+    "zh:47fb41b18b74073f557dbcd6aad2183e416293405ccd70c0691a279cfe97f8cd",
+    "zh:517e2f2764d671c22d22def0384fdfc521b456458189189c0363375495d114dc",
+    "zh:5a49a2003636f2b8a547d494a6c06d43d62a68299775305408c52eff22b1c11f",
+    "zh:66d4e716920ada84b0c768f4aca4c8948388995462923349a01bd3818d82b618",
+    "zh:7599f652e89a3f18fa4b76a59d115cc63255cc36ce6b273850509ba25031abca",
+    "zh:9c3e38ae7e670de973b6255d7050f526cd2b3ca7c383d7ba7226fc204d97c507",
+    "zh:d04b046023fa9fd69def678f27e001c298ea34fc99ba51f835cda82e496fdb57",
+    "zh:d9acd8810f6660cd51bb4c25596632984ae18e93340c82a102d074c6eac95151",
+    "zh:e161bcb9a22607270b980eeff2ba693335fb62d6978516dff93dd4c91cda99b3",
+    "zh:ef47502f08cfcb5311b7b16a7905e0052bf28359e07cc00ed080ef454e0946cf",
+    "zh:f0640ddb52e7e90c5006ff571f6ad0554e593665320c764c57a3d8b7ec31b490",
+  ]
+}

modules/authentik/main.tf

@@ -20,18 +20,42 @@ resource "authentik_provider_saml" "this" {
   signing_kp         = each.value.signing_kp
 }
 
+# Resolve oauth2 flows by slug and scope mappings by managed identifier, and
+# read client secrets from Vault so nothing sensitive is committed.
+data "authentik_flow" "oauth2_authorization" {
+  for_each = var.providers_oauth2
+  slug     = each.value.authorization_flow
+}
+
+data "authentik_flow" "oauth2_invalidation" {
+  for_each = var.providers_oauth2
+  slug     = each.value.invalidation_flow
+}
+
+data "authentik_property_mapping_provider_scope" "oauth2" {
+  for_each     = { for k, v in var.providers_oauth2 : k => v if length(v.scope_mappings) > 0 }
+  managed_list = each.value.scope_mappings
+}
+
+data "vault_kv_secret_v2" "oauth2" {
+  for_each = { for k, v in var.providers_oauth2 : k => v if v.client_secret_vault != null }
+  mount    = each.value.client_secret_vault.mount
+  name     = each.value.client_secret_vault.path
+}
+
 resource "authentik_provider_oauth2" "this" {
   for_each = var.providers_oauth2
 
   name                  = each.value.name
-  authorization_flow    = each.value.authorization_flow
+  authorization_flow    = data.authentik_flow.oauth2_authorization[each.key].id
-  invalidation_flow     = each.value.invalidation_flow
+  invalidation_flow     = data.authentik_flow.oauth2_invalidation[each.key].id
   client_type           = each.value.client_type
   client_id             = each.value.client_id
-  client_secret         = each.value.client_secret
+  client_secret         = each.value.client_secret_vault != null ? data.vault_kv_secret_v2.oauth2[each.key].data["client_secret"] : null
-  property_mappings     = each.value.property_mappings
+  property_mappings     = try(data.authentik_property_mapping_provider_scope.oauth2[each.key].ids, [])
   signing_key           = each.value.signing_key
   access_token_validity = each.value.access_token_validity
+  allowed_redirect_uris = each.value.redirect_uris
 }
 
 resource "authentik_provider_ldap" "this" {

modules/authentik/variables.tf

@@ -24,13 +24,24 @@ variable "providers_saml" {
 
 variable "providers_oauth2" {
   type = map(object({
-    name                  = string
+    name               = string
-    authorization_flow    = string
+    authorization_flow = string # flow slug, resolved to id via data.authentik_flow
-    invalidation_flow     = string
+    invalidation_flow  = string # flow slug, resolved to id via data.authentik_flow
-    client_type           = optional(string, "confidential")
+    client_type        = optional(string, "confidential")
-    client_id             = string
+    client_id          = string
-    client_secret         = optional(string, null)
+    # client_secret is never committed. Point at a Vault kv-v2 secret whose
-    property_mappings     = optional(list(string), [])
+    # `client_secret` key holds the value (seeded out of band); TF reads it.
+    client_secret_vault = optional(object({
+      mount = string
+      path  = string
+    }), null)
+    # Managed identifiers of scope property mappings (e.g.
+    # goauthentik.io/providers/oauth2/scope-openid). Resolved to ids.
+    scope_mappings = optional(list(string), [])
+    redirect_uris = optional(list(object({
+      matching_mode = optional(string, "strict")
+      url           = string
+    })), [])
     signing_key           = optional(string, null)
     access_token_validity = optional(string, "minutes=10")
   }))

modules/authentik/versions.tf

@@ -5,5 +5,9 @@ terraform {
       source  = "goauthentik/authentik"
       version = ">= 2026.5.0"
     }
+    vault = {
+      source  = "hashicorp/vault"
+      version = ">= 4.0.0"
+    }
   }
 }