Onboard OpenBao as an Authentik OIDC client

Adds config/providers_oauth2/vault.yaml so human logins to OpenBao go
through Authentik SSO (bao CLI and the web UI). Machine auth (approle,
kubernetes, CI) and break-glass are unchanged and stay on the OpenBao side.

Extends the oauth2 provider module so a config may generate its own client
secret instead of reading a pre-seeded one: client_secret_vault.generate
creates a random_password and writes {client_id, client_secret} to the given
kv-v2 path. Providers without the flag keep the existing read-only data source
behaviour. This is what lets the provider land with no manual Vault seed.

Gates the new application with akP-vault-admin and nests it in
akR-global-admin, matching how every other app in this repo is bound.

modules/authentik/.terraform.lock.hcl

@@ -22,6 +22,29 @@ provider "registry.opentofu.org/goauthentik/authentik" {
   ]
 }
 
+provider "registry.opentofu.org/hashicorp/random" {
+  version     = "3.9.0"
+  constraints = ">= 3.6.0"
+  hashes = [
+    "h1:8EQU5KSxezcjo/phRSe69rDOI0lk4pSaggj7FsskYp8=",
+    "zh:03f1114cc20b8913523735ab76e0f0a2b16ce13c92923a53304bf85f07fc0dbc",
+    "zh:105b678ee72322a3067f105d7e05e940f6143238f377f6e87ff4ec909246ac2a",
+    "zh:55f3bbf13ea18cbace61a706566a80f25f33fe2b1780b6f3d7b582af2a05b6d2",
+    "zh:63adf996db48f082f7a6351eb485e219cd88795fc71e6ec60a837263ab0d2cb1",
+    "zh:7e99550738a4e3cc68b8a467714b0d69371025fe95e3326d5323d026d55653e9",
+    "zh:8342b54af3a18a37e075eeae61be57f4de2ba71b35d95c5075d402dd2c1f289d",
+    "zh:83ee18e32ac9dd5fc91298554b7c4cfa4c3a1db50f4c797945637cc93c0844ae",
+    "zh:993ecc0adbf6bd535a59fbc9b735d8c33950e6f6eb5e621d750da9b71d65d80a",
+    "zh:ad722bc59d4edbf1415e827fc007c0efe6e0e9462d5568bae20b34be1058a261",
+    "zh:ae9448e1f87b2f9a6c5197a0e9862162ec6b137cb3a3835e11522995d8939e7c",
+    "zh:bc9cdd3aac784f759125c6627f6f6416e8726a1c184eb9cf3e55b9edbc94c627",
+    "zh:c8e35b89572ba1c40a9b20022e033a3395fb8d42e7604d50c900f193ba10382e",
+    "zh:e2deaa8a9975ef81d9f62baed12c41286918b0a10908e0e031f13f69a3b730a1",
+    "zh:ee39707557210a0ab1098aa357d2cdfe502e5a312d0dbdffb09d08facc4d3fc5",
+    "zh:f81afe4eb63e8aa9e0ea71be6c990f0dc69cb360e7191c0742a991f4a5081b64",
+  ]
+}
+
 provider "registry.opentofu.org/hashicorp/vault" {
   version     = "5.10.1"
   constraints = ">= 4.0.0"

modules/authentik/main.tf

@@ -136,12 +136,53 @@ data "authentik_property_mapping_provider_scope" "oauth2" {
   managed_list = each.value.scope_mappings
 }
 
+locals {
+  # Providers whose client secret is pre-seeded in Vault and only read here.
+  oauth2_secret_read = {
+    for k, v in var.providers_oauth2 : k => v
+    if v.client_secret_vault != null && !v.client_secret_vault.generate
+  }
+  # Providers whose client secret is generated here and published to Vault, so
+  # onboarding needs no operator seeding the path first.
+  oauth2_secret_generate = {
+    for k, v in var.providers_oauth2 : k => v
+    if v.client_secret_vault != null && v.client_secret_vault.generate
+  }
+
+  oauth2_client_secret = merge(
+    { for k, v in local.oauth2_secret_read : k => data.vault_kv_secret_v2.oauth2[k].data["client_secret"] },
+    { for k, v in local.oauth2_secret_generate : k => random_password.oauth2_client_secret[k].result },
+  )
+}
+
 data "vault_kv_secret_v2" "oauth2" {
-  for_each = { for k, v in var.providers_oauth2 : k => v if v.client_secret_vault != null }
+  for_each = local.oauth2_secret_read
   mount    = each.value.client_secret_vault.mount
   name     = each.value.client_secret_vault.path
 }
 
+# Alphanumeric only: the secret is pasted into consumer configs and CLI flags,
+# where punctuation is an easy way to hit shell/URL escaping bugs.
+resource "random_password" "oauth2_client_secret" {
+  for_each = local.oauth2_secret_generate
+
+  length  = 64
+  special = false
+}
+
+# Publish the generated credential so consumers (terraform-vault, app configs)
+# read it from Vault instead of an operator copying it out of Authentik.
+resource "vault_kv_secret_v2" "oauth2_client_secret" {
+  for_each = local.oauth2_secret_generate
+
+  mount = each.value.client_secret_vault.mount
+  name  = each.value.client_secret_vault.path
+  data_json = jsonencode({
+    client_id     = each.value.client_id
+    client_secret = random_password.oauth2_client_secret[each.key].result
+  })
+}
+
 # Default JWT signing key for OAuth2 providers. Without a signing_key Authentik
 # signs ID tokens with HS256, which RS256-only RP clients (argocd, grafana, ...)
 # reject. Look up the estate's RSA keypair by name so providers default to RS256.
@@ -157,7 +198,7 @@ resource "authentik_provider_oauth2" "this" {
   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_vault != null ? data.vault_kv_secret_v2.oauth2[each.key].data["client_secret"] : null
+  client_secret      = lookup(local.oauth2_client_secret, each.key, null)
   property_mappings = concat(
     try(data.authentik_property_mapping_provider_scope.oauth2[each.key].ids, []),
     [authentik_property_mapping_provider_scope.groups_hierarchical.id],

modules/authentik/variables.tf

@@ -60,9 +60,13 @@ variable "providers_oauth2" {
     client_id          = string
     # client_secret is never committed. Point at a Vault kv-v2 secret whose
     # `client_secret` key holds the value (seeded out of band); TF reads it.
+    # generate = true flips that around: the secret is created here and written
+    # to that path as {client_id, client_secret}, so onboarding needs no manual
+    # seed. Requires write access to the kv path.
     client_secret_vault = optional(object({
-      mount = string
-      path  = string
+      mount    = string
+      path     = string
+      generate = optional(bool, false)
     }), null)
     # Managed identifiers of scope property mappings (e.g.
     # goauthentik.io/providers/oauth2/scope-openid). Resolved to ids.

modules/authentik/versions.tf

@@ -9,5 +9,9 @@ terraform {
       source  = "hashicorp/vault"
       version = ">= 4.0.0"
     }
+    random = {
+      source  = "hashicorp/random"
+      version = ">= 3.6.0"
+    }
   }
 }