vault: revert to confidential client, Web UI only (no CLI)

services/kanidm/default.nix

@@ -43,12 +43,10 @@
 
       systems.oauth2.openbao = {
         displayName = "OpenBao Secrets";
-        # Public client for CLI support (uses PKCE instead of client secret)
-        public = true;
-        enableLocalhostRedirects = true;
-        # Both CLI (localhost) and Web UI callback URLs
+        # Web UI callback only (CLI localhost not supported with confidential clients)
         originUrl = "https://vault.home.2rjus.net:8200/ui/vault/auth/oidc/oidc/callback";
         originLanding = "https://vault.home.2rjus.net:8200/";
+        basicSecretFile = config.vault.secrets.openbao-oauth2.outputDir;
         preferShortUsername = true;
         # Allow groups scope for role binding
         scopeMaps.admins = [ "openid" "profile" "email" "groups" ];
@@ -86,6 +84,14 @@
     group = "kanidm";
   };
 
+  # Vault secret for OpenBao OAuth2 client secret
+  vault.secrets.openbao-oauth2 = {
+    secretPath = "services/openbao/oauth2-client-secret";
+    extractKey = "password";
+    services = [ "kanidm" ];
+    owner = "kanidm";
+    group = "kanidm";
+  };
 
   # Note: Kanidm does not expose Prometheus metrics
   # If metrics support is added in the future, uncomment:

terraform/vault/approle.tf

@@ -106,6 +106,7 @@ locals {
         "secret/data/hosts/kanidm01/*",
         "secret/data/kanidm/*",
         "secret/data/services/grafana/*",
+        "secret/data/services/openbao/*",
       ]
     }
 

terraform/vault/oidc.tf

@@ -1,10 +1,11 @@
 # OIDC authentication backend for Kanidm integration
-# Using a public client (no secret) to support CLI localhost redirects
+# Web UI only - CLI localhost redirects not supported with confidential clients
 resource "vault_jwt_auth_backend" "oidc" {
   path               = "oidc"
   type               = "oidc"
   oidc_discovery_url = "https://auth.home.2rjus.net/oauth2/openid/openbao"
   oidc_client_id     = "openbao"
+  oidc_client_secret = random_password.auto_secrets["services/openbao/oauth2-client-secret"].result
   default_role       = "default"
 
   tune {
@@ -27,7 +28,6 @@ resource "vault_jwt_auth_backend_role" "admin" {
   role_type    = "oidc"
 
   allowed_redirect_uris = [
-    "http://localhost:8250/oidc/callback",
     "https://vault.home.2rjus.net:8200/ui/vault/auth/oidc/oidc/callback",
   ]
 }
@@ -43,7 +43,6 @@ resource "vault_jwt_auth_backend_role" "default" {
   role_type    = "oidc"
 
   allowed_redirect_uris = [
-    "http://localhost:8250/oidc/callback",
     "https://vault.home.2rjus.net:8200/ui/vault/auth/oidc/oidc/callback",
   ]
 }

terraform/vault/secrets.tf

@@ -115,6 +115,11 @@ locals {
       password_length = 64
     }
 
+    # OpenBao OAuth2 client secret (for Kanidm OIDC)
+    "services/openbao/oauth2-client-secret" = {
+      auto_generate   = true
+      password_length = 64
+    }
 
     # NKey for nixos-exporter NATS cache sharing
     "shared/nixos-exporter/nkey" = {