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How do I stop Docker trying to pull from IPv6? (aussie.zone)
submitted 1 year ago by to c/selfhosted@lemmy.world
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I'm currently trying to install Docker on my old Raspberry Pi (3 Model B+) to host some personal projects. When I run docker run hello-world, I get:

Unable to find image 'hello-world:latest' locally
docker: Error response from daemon: Get "https://registry-1.docker.io/v2/library/hello-world/manifests/sha256:ec153840d1e635ac434fab5e377081f17e0e15afab27beb3f726c3265039cfff": dial tcp [2600:1f18:2148:bc00:eff:d3ae:b836:fa07]:443: connect: network is unreachable

My Internet connection does not support IPv6 at all, which would explain why this error occurs. But how do I force docker-pull to only use IPv4?

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[–] 2 points 1 year ago* (7 children)

What version of Pi OS are you running?

(we can move to DMs if you wish, it will be less polluting, or stay in the comment thread if you don't feel safe in DMs)

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  • [–] [S] 1 point 1 year ago* (6 children)

    I'm happy to keep it public if only for the off chance that if we find a solution it might some day help someone else with the same issue. The thread'll fall down in the rankings naturally over time anyway so I wouldn't worry about polluting anything for people not actively seeking it out.

    I'm not 100% sure how to find the OS version, but uname -a outputs [...]6.12.25+rpt-rpi-v8[...]. /etc/os-release contains "Debian GNU/Linux 12 (bookworm)". It should be whatever was latest as of a month or two ago when I installed the OS fresh.

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  • [–] 2 points 1 year ago* (last edited 1 year ago) (5 children)

    I have read the rest of the comments to see what you already tried. I was about yo tell you to use sysctl to disable ipv6 but it looks like that is already done.

    As a matter of fact, it looks like you have no ipv6 address at all. Which makes me think that your DNS config might be off, as it shouldn't even attempt an ipv6 resolution.

    Can you show me the content of /etc/resolv.conf ?

    Also install "dig" if you dont have it already and show the output of

    dig registry-1.docker.io
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  • [–] [S] 1 point 1 year ago* (4 children) 
    $ dig registry-1.docker.io

; <<>> DiG 9.18.33-1~deb12u2-Debian <<>> registry-1.docker.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50801
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;registry-1.docker.io.          IN      A

;; ANSWER SECTION:
registry-1.docker.io.   33      IN      A       54.210.249.78
registry-1.docker.io.   33      IN      A       44.218.153.24
registry-1.docker.io.   33      IN      A       107.20.112.188
registry-1.docker.io.   33      IN      A       34.234.222.10
registry-1.docker.io.   33      IN      A       34.195.83.243
registry-1.docker.io.   33      IN      A       52.21.128.203
registry-1.docker.io.   33      IN      A       52.0.248.137
registry-1.docker.io.   33      IN      A       52.207.69.161

;; Query time: 47 msec
;; SERVER: 192.168.20.1#53(192.168.20.1) (UDP)
;; WHEN: Tue Aug 12 22:27:45 AEST 2025
;; MSG SIZE  rcvd: 177
$ cat /etc/resolv.conf
# Generated by NetworkManager
search Home
nameserver 192.168.20.1

    edit: oh, and in my router's configuration:

    • Primary DNS Server:9.9.9.9
    • Secondary DNS Server:1.1.1.1
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  • [–] 2 points 1 year ago (3 children)

    Well this is getting weird.

    Have you tried checking if your os has a resolution cashe active? If so, try to flush it.

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  • [–] [S] 1 point 1 year ago* (2 children)

    I never set one up myself, and this 11 year-old thread implies that Raspbian doesn't have one set up by default. It is a very old thread though, so could be wrong.

    edit: this is more recent and also says Raspbian doesn't have DNS caching by default

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  • [–] 2 points 1 year ago (1 child)

    At this point I am assuming that it is actually a docker issue.

    Can you show your docker daemon configuration?

    Hard to tell where it is on your machine. Try ~/.docker/daemon.json, or maybe /etc/docker/daemon.json... Else look for it haha

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  • [–] [S] 1 point 1 year ago

    There's a ~/.docker/config.json. In that there're some auths, with keys https://index.docker.io/v1/, https://index.docker.io/v1/access-token, and https://index.docker.io/v1/refresh-token, and then there's "currentContext": "rootless".

    There's ~/.docker/contexts/meta/[a long hex string]/meta.json, with {"Name":"rootless","Metadata":{"Description":"Rootless mode"},"Endpoints":{"docker":{"Host":"unix:///run/user/1000/docker.sock","SkipTLSVerify":false}}}.

    The only file in /etc/docker is key.json.

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