Cli: Add support for build-time extra_hosts for Version 3

[kinnalru]

It work well for Version 2.3 since https://github.com/docker/compose/issues/5282 but invalid for Version 3

[anibalrivero]

Is there a known workaround for this? Other than building the images outside of compose.

[kinnalru]

I'am using Version 2.3 for building images and other version for deploying.

[Stono]

Hi,
Is there any update on this? It feels like a real omission from v3 when it is supported by the docker --add-host command.

I really don't want to adjust our build process to building outside of compose, and I can't use version 2.3 because I lose support for other build aspects I need from 3?

A work around to pass --add-host would be great?

[nicosmaris]

For the following Dockerfile:

FROM byrnedo/alpine-curl

The following docker-compose.yml works (if you replace host and IP with your case):

version:          '2.3'
services:
  tmp:
    build:
      context:    .
      extra_hosts:
        - "host:IP"
    command:      -kIL https://host
    tty:          true
    stdin_open:   true

But the following fails (if you replace host and IP with your case):

version:          '3'
services:
  tmp:
    build:
      context:    .
      extra_hosts:
        - "host:IP"
    command:      -kIL https://host
    tty:          true
    stdin_open:   true

The error at docker-compose up is:

The Compose file is invalid because:                                                                                                                                                 
services.tmp.build contains unsupported option: 'extra_hosts' 

[posix4e]

Any updates this would be very nice

[lmammino]

Having this would be great. Currently doing weird hacks to circumvent this limitation... :(

[i3inc]

is this on the radar as something to be fixed?

[ghevge]

One more vote here for fixing this limitation. I was trying with 3.5 and the issue is still there

[thaJeztah]

This was added to the compose 3.9 schema in https://github.com/docker/cli/pull/2517. The 3.9 schema is not yet released (will be together with the next 20.x release of docker), and will have to be implemented in docker-compose as well (as the docker CLI itself doesn't use the build section of compose files, and only uses docker-compose files for docker stack deploy).

I'm closing this issue here, but subscribe / participate on https://github.com/docker/compose/issues/7323 which is a ticket in the docker-compose repository for this