Move the 503 -> 429 mapping into Synapse's frontend rather than HAProxy defaults

Author: benbz

charts/matrix-stack/configs/haproxy/haproxy.cfg.tpl

@@ -1,5 +1,5 @@
 {{- /*
-Copyright 2024 New Vector Ltd
+Copyright 2024-2025 New Vector Ltd
 
 SPDX-License-Identifier: AGPL-3.0-only
 */ -}}
@@ -66,16 +66,6 @@ defaults
   compression algo gzip
   compression type text/plain text/html text/xml application/json text/css
 
-  # if we hit the maxconn on a server, and the queue timeout expires, we want
-  # to avoid returning 503, since that will cause cloudflare to mark us down.
-  #
-  # https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#1.3.1 says:
-  #
-  #   503  when no server was available to handle the request, or in response to
-  #        monitoring requests which match the "monitor fail" condition
-  #
-  errorfile 503 /usr/local/etc/haproxy/429.http
-
   # Use a consistent hashing scheme so that worker with balancing going down doesn't cause
   # the traffic for all others to be shuffled around.
   hash-type consistent sdbm

charts/matrix-stack/configs/haproxy/429.http.tpl renamed to charts/matrix-stack/configs/synapse/429.http.tpl

@@ -1,5 +1,5 @@
 {{- /*
-Copyright 2024 New Vector Ltd
+Copyright 2024-2025 New Vector Ltd
 
 SPDX-License-Identifier: AGPL-3.0-only
 */ -}}

charts/matrix-stack/configs/synapse/partial-haproxy.cfg.tpl

@@ -25,6 +25,16 @@ frontend synapse-http-in
   # same as http log, with %Th (handshake time)
   log-format "%ci:%cp [%tr] %ft %b/%s %Th/%TR/%Tw/%Tc/%Tr/%Ta %ST %B %CC %CS %tsc %ac/%fc/%bc/%sc/%rc %sq/%bq %hr %hs %{+Q}r"
 
+  # if we hit the maxconn on a server, and the queue timeout expires, we want
+  # to avoid returning 503, since that will cause cloudflare to mark us down.
+  #
+  # https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#1.3.1 says:
+  #
+  #   503  when no server was available to handle the request, or in response to
+  #        monitoring requests which match the "monitor fail" condition
+  #
+  errorfile 503 /synapse/429.http
+
   capture request header Host len 32
   capture request header Referer len 200
   capture request header User-Agent len 200

charts/matrix-stack/templates/haproxy/_helpers.tpl

@@ -20,8 +20,6 @@ app.kubernetes.io/version: {{ include "element-io.ess-library.labels.makeSafe" .
 {{- with required "element-io.haproxy.configmap-data missing context" .context -}}
 haproxy.cfg: |
 {{- tpl ($root.Files.Get "configs/haproxy/haproxy.cfg.tpl") (dict "root" $root "context" .) | nindent 2 }}
-429.http: |
-{{- (tpl ($root.Files.Get "configs/haproxy/429.http.tpl") dict) | nindent 2 }}
 {{- end -}}
 {{- end -}}
 

charts/matrix-stack/templates/synapse/_helpers.tpl

@@ -223,6 +223,8 @@ redis.conf: |
 
 {{- define "element-io.synapse-haproxy.configmap-data" -}}
 {{- $root := .root -}}
+429.http: |
+{{- (tpl ($root.Files.Get "configs/haproxy/429.http.tpl") dict) | nindent 2 }}
 path_map_file: |
 {{- (tpl ($root.Files.Get "configs/synapse/path_map_file.tpl") (dict "root" $root)) | nindent 2 }}
 path_map_file_get: |