caddy-frontend: Support stale-if-error

software/caddy-frontend/buildout.hash.cfg

@@ -74,7 +74,7 @@ md5sum = 8cde04bfd0c0e9bd56744b988275cfd8
 
 [template-trafficserver-records-config]
 filename = templates/trafficserver/records.config.jinja2
-md5sum = 3c342b0388f94f819b04b05b46744427
+md5sum = 3a4e378932ffc7768426bb7a897e2c45
 
 [template-trafficserver-storage-config]
 filename = templates/trafficserver/storage.config.jinja2

software/caddy-frontend/templates/trafficserver/records.config.jinja2

@@ -25,6 +25,8 @@ CONFIG proxy.config.log.logfile_dir STRING {{ ats_directory['log'] }}
 # Implement RFC 5861 with core
 CONFIG proxy.config.http.cache.open_write_fail_action INT 2
 CONFIG proxy.config.body_factory.template_sets_dir STRING  {{ ats_configuration['templates-dir'] }}
+# Support stale-if-error by returning cached content on backend 5xx or unavailability
+CONFIG proxy.config.http.negative_revalidating_enabled INT 1
 
 ##############################################################################
 # Thread configurations. Docs: