IPv6 services now resolving to IPv4 addresses breaking jobs

Problem

Previously GitLab services defined in the gitlab-ci.yml file were available on IPv6 addresses. After changing listen configurations to listen on IPv6, some jobs are now using IPv4 addresses and failing.

Observed Behavior

Services that previously resolved to IPv6 addresses are now resolving to IPv4 addresses:

• Before (IPv6): fd76:5338:4685:1:0:242:ac11:3
• Now (IPv4): 172.17.0.3

This causes jobs to fail when they attempt to connect to services on the expected IPv6 addresses.

Questions

1. Why was this changed recently?
2. There's no mention of IPv4 vs IPv6 in public documentation - this needs clarification.

Related

• Caused by: MR !5980 (merged) - Changes to network configuration that resulted in IPv4 addresses being used instead of IPv6
• Fix in progress: MR !6027 (merged) which adds IPv6 address support when emulating links functionality and fixes IPv6 support for the default network adapter

Suggested workarounds

• Re-configure services to bind to IPv4
• Utilise FF_NETWORK_PER_BUILD (untested)