DOCKER_BUILDKIT=1 prevents custom networks using docker build --network

[jhrabi]

Not sure if this is a Docker CLI or BuildKit issue, but when using BuildKit by specifying DOCKER_BUILDKIT=1 as part of a Docker Build in Docker v18.09, a custom Docker network is no longer recognized.

So for example, a command of "docker build --network demo-net ." will now return:

Error response from daemon: network mode "demo-net" not supported by buildkit

Seemingly this means that it only supports specific network modes are being supported, and not custom Docker networks.

[AkihiroSuda]

cc @kunalkushwaha

[antifuchs]

I have just stumbled across this too (running an apt_cache container locally to support my builds); believe this is intentional: this conditional pretty much says that no network modes other than host, none, or the default are supported /:

[MarcosMorelli]

im also looking at this one. I want to build and add to a custom network along with mongodb to run integration tests;

[crevao]

I'm also very interested in this!

[MarcosMorelli]

any updates at this one?

[snakenstein]

I faced this issue too when running build in Swarm from CI server. We attach to network where container with private Nuget server resides to pull required packages.
And because of this limitation we can't use buildkit for such builds.

[barrelmaker97]

Have run into this issue as well trying to build an image that uses a Redis instance for testing during the build process. Any updates?

I have just stumbled across this too (running an apt_cache container locally to support my builds); believe this is intentional: this conditional pretty much says that no network modes other than host, none, or the default are supported /:

I suspect there just wasn't time/focus to implement the feature, it's marked as a roadblock item in the comment on moby/moby#40379 - if it's removed it would be a definite functional regression.

[SuperSandro2000]

This is a real blocker for me cause I cannot access my DNS server in another container while building.

[kanduvisla]

Any updates or workaround on this one?

[AkihiroSuda]

workaround: export DOCKER_BUILDKIT=0

[kanduvisla]

@AkihiroSuda that's not really a workaround since then you cannot use the features provided by docker buildkit. Like secrets, in my case.