Docker builds failing, bad bridge?

Image Builds
1

I have just installed a fresh docker (Docker version 29.1.2, build 890dcca
) on an up-to-date build of Ubuntu 24.04.3 LTS, and all my docker builds are failing - first theres a bunch of "Temporary failure resolving ‘’”, then its unable to locate any package, like this:

60.25 Reading package lists…
60.26 Building dependency tree…
60.26 Reading state information…
60.26 Package uuid-runtime is not available, but is referred to by another package.
60.26 This may mean that the package is missing, has been obsoleted, or
60.26 is only available from another source
60.26 
60.26 E: Unable to locate package cpanminus
60.26 E: Unable to locate package gcc
60.26 E: Unable to locate package git

If I try the same docker build and append —network=host, it works. 

So it seems something is broken in the default bridge network. Theres nothing otherwise unusual about my system that I can see as a possible cause. Suggestions for debugging this will be gratefully received.
2

Have you also tried to run containers without building? Does this command work?

docker run --rm -it curlimages/curl example.org

It just starts a container without building an image. Image builds are not using Docker containers so I am curious whether a simple container works or not.

You should also check your local network. If for example 172.16 exists on your LAN or for anything else locally, that could break docker network.

You could also try running a container on a user defined docker network.

docker network create test
docker run --rm -it --network test curlimages/curl example.org
3

Aha. Thankyou! I have CloudflareWARP installed, using 172.16.0.0. I thought it didn’t conflict with docker because docker0 was 172.17.0.1. But evidently it does conflict because disabling CloudFlareWARP fixes my builds.

4

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