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Cannot assign requested address - bind(2) for "::1"

Vinh  docker puma rails

Today I encountered this error during running Puma in Dockerm, using official 2.3 Ruby image.

Cannot assign requested address - bind(2) for "::1" port 3000 (Errno::EADDRNOTAVAIL)

Google search found out that https://github.com/puma/puma/issues/1062 and a fixed in https://github.com/puma/puma/pull/1318.

However, the fixed wasn’t working for me. The core of issue is somehow even the docker container doesn’t support ipv6 but we have an entry like this:

::1 localhost ip6-localhost ip6-loopback

in host file. This #1318 supposed to fixed it. It seems the issue caugh by webpack dev server as well besde Puma. At that point, I was frustrated and just try to find a way to disable ipv6 in docker container.

If you’re using docker compose you can add this line to disable ipv6, hence remove the ::1 entry from host file:

  sysctls:
      net.ipv6.conf.all.disable_ipv6: 0