Allow additional build flags when building a container

[marchingphoenix]

When building a devcontainer from dockerfile it will be useful to expose out additional docker build args that can be used when the container is created.
This can be done either by direct linking of these commands to the build property in the .devcontainer.json or via a catch-all array like build.command_flags: ["--network=host", "--compress"] etc

Example, a dockerfile is installing packages from an internal repository but your machine is on a vpn. Would need to pass --network=host to the build command to ensure that traversal happens correctly on Linux hosts.

[296951]

Any word on when this might get added? We work in Amazon Workspaces Linux instances and in order to build/run Docker images/containers you need to pass --network host to allow the running container to access the network. There is already a runArgs that allows passing Docker run options there also needs to be a buildOpts to allow passing docker build options

I can work around this by building the container outside vscode and then open my devcontainer project in vscode. I then use the "runArgs": ["--network=host"]. This is less than optimal.

We are trying to make this a standard for projects we support but without this it is difficult.

[felipecrs]

In my case I would like to use --cache-from repo/devcontainer:cache as my devcontainer takes around 30 minutes to build, so I can prebuild it in CI and let the VSCode leverage the build cache.

[felipecrs]

For some cases (such as mine), the following workaround can be useful:

// pre build image to leverage --cache-from
"initializeCommand": [
  "docker",
  "build",
  "--target=devcontainer",
  "--cache-from=armdocker.rnd.ericsson.se/proj-river/cicd-devcontainer",
  "."
],

This will build the image the way I want, and later when VS Code tries to build it, it will be already cached and will be almost instantaneous.

[ismailazerty]

Hello,
any update on this ticket ? we really need this feature to be able to use --network=host.

Regards

[James-Mart]

Another very important use-case I don't see mentioned above is that this feature is needed in order to use docker "build --ssh=default".

This is used to allow the host ssh-agent to sign for build commands (such as pulling from a private github repository using ssh).