Fix keycloak with large headers

nginx keeps headers in a buffer, and unfortunately keycloak can produce
long headers. By increasing the size of this buffer, we can prevert 502
errors on some endpoints (particularly matrix)

Change-Id: I4e5fba827817d4c4a86f9316ccd2de6bb4e46ceb
Reviewed-on: https://git.clicks.codes/c/Clicks/NixFiles/+/187
Tested-by: Skyler Grey <minion@clicks.codes>
Reviewed-by: Samuel Shuert <coded@clicks.codes>
diff --git a/modules/common/keycloak.nix b/modules/common/keycloak.nix
index 587744d..27da3c8 100644
--- a/modules/common/keycloak.nix
+++ b/modules/common/keycloak.nix
@@ -41,5 +41,10 @@
       passwordFile = config.sops.secrets.clicks_keycloak_db_password.path;
     };
   };
-  
+
+  services.nginx.virtualHosts."login.clicks.codes".locations."/".extraConfig = ''
+    proxy_buffers 16 32k;
+    proxy_buffer_size 64k;
+    proxy_busy_buffers_size 64k;
+  '';
 }