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Frequent Gem::RemoteFetcher::UnknownHostError timed out over the last week

Stan Hu's Avatar

Stan Hu

06 May, 2019 11:42 AM

I thought I had reported this in another discussion, but now I can't find it. Over the past week, we've been seeing frequently failures talking to RubyGems in our CI, such as:

Retrying download gem from due to error (2/4): Gem::RemoteFetcher::UnknownHostError timed out (

  1. 1 Posted by Tinco on 07 May, 2019 12:54 AM

    Tinco's Avatar

    Same here, perhaps more IPv6 problems?

    It's proving difficult to deal with, I don't have a good solution yet and it's making it really hard to deploy.

  2. 2 Posted by Brian on 08 May, 2019 09:44 AM

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    +1 here. Intermittent issue in my Gitlab CI while building my docker image.

  3. Support Staff 3 Posted by sonalkr132 on 15 May, 2019 12:22 PM

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    We have been monitoring our fastly 5xx for the past few days. We don't see any timeout for /gems path. Can you please confirm if your builds are still failing?

  4. 4 Posted by Stan Hu on 15 May, 2019 04:05 PM

    Stan Hu's Avatar

    It sounds like the errors wouldn't show up on Fastly because the DNS lookups just fail on the client before any attempts are made. It sounds like the wrokaround is to force IPv4 lookups:

  5. Support Staff 5 Posted by sonalkr132 on 15 May, 2019 04:13 PM

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    AFAIK, Gitlab doesn't use IPv6 hosts[1]. Intermittent timeout on gem path seems unrelated to IPv6 issue to me.

  6. 6 Posted by Stan Hu on 15 May, 2019 05:49 PM

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    GitLab Runners are configured to use IPv6. That issue is about users accessing with IPv6, which is a different issue.

  7. Support Staff 7 Posted by sonalkr132 on 13 Jul, 2020 07:45 AM

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    Hi Stan,

    Sorry about the delay in the resolution here. I personally didn't have access to take any steps here until recently. I have opened a support ticket with Fastly and hopefully, we will make some progress here. Can you please confirm if you are still having this issue?
    If yes, I would like to forward some debugging info about your host/IP to the Fastly team.

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