FWIW, more discussion about that CA change is at T386836 (though it’s not clear to me how that could cause a host name lookup failure o_O)

A revert commit has been proposed at https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CentralAuth/+/1121043

I +2ed that revert by now, but it’ll take quite some time for gate-and-submit to reach it :|

In T386851#10564639, @Lucas_Werkmeister_WMDE wrote:

FWIW, more discussion about that CA change is at T386836 (though it’s not clear to me how that could cause a host name lookup failure o_O)

I added some in-place debugging to LegacyHandler.php:

public function __construct(
        $stream,
        $useLegacyFilter = false,
        $level = Logger::DEBUG,
        $bubble = true
) {
        parent::__construct( $level, $bubble );
        trigger_error("URI is {$stream}\n", E_USER_WARNING);
        $this->uri = $stream;
        $this->useLegacyFilter = $useLegacyFilter;
}

This is the result:

mergeMessageFileList.php generated PHP notices/warnings:
Warning: URI is udp://deployment-mwlog02.deployment-prep.eqiad1.wikimedia.cloud:8420/{channel}
...

deployment-mwlog02.deployment-prep.eqiad1.wikimedia.cloud is a resolvable hostname so it's unclear what's going on.

This is the message that is being logged at the time of the socket_sendto() call:

MessageCache 2025-02-19 18:28:06.710940 [608821d4d8ba83c01bd9b82d] deployment-deploy04 aawiki 1.44.0-alpha MessageCache DEBUG: MessageCache using store Wikimedia\ObjectCache\EmptyBagOStuff {"class":"Wikimedia\\ObjectCache\\EmptyBagOStuff"}

OK. I remember now. Scap runs mergeMessageFileList.php in a container that does not have network access enabled, so anything that generates a log message will trigger this type of situation.

Mentioned in SAL (#wikimedia-releng) [2025-02-19T21:28:45Z] <dancy> Reenabled https://integration.wikimedia.org/ci/view/Beta/job/beta-scap-sync-world/ (T386851)