As part of T255568, a test of the envoy service proxy disabled listening on 127.0.0.1 for services. When this was applied to restbase-dev hosts, started failing to connect to the configured services as it was attempting to connect to 127.0.0.1 and then failing.
$ curl localhost:7233/en.wikipedia.org/v1/feed/announcements {"type":"https://mediawiki.org/wiki/HyperSwitch/errors/server_error","title":"Site info fetch failed.","method":"get","detail":"connect ECONNREFUSED 127.0.0.1:6500","uri":"/en.wikipedia.org/v1/feed/announcements"}
Restbase only has "localhost" defined for these services, the IP is not hardcoded. This behaviour persisted after a restart.
Meanwhile the IPv6 proxied services are looking fine:
curl -v localhost:6017/en.wikipedia.org/v1/feed/announcements
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 6017 (#0)
...
<
* Curl_http_done: called premature == 0
* Connection #0 to host localhost left intact
{"announce":[]}The ports in these examples differ but it's the same for all services.