Add support for additional_contexts in build service config

[laurazard]

What I did

Implement support for additional_contexts as per compose-spec/compose-spec#307 and compose-spec/compose-go#354.

Related issue

closes #9461
closes #9961

(not mandatory) A picture of a cute animal, if possible in relation to what you did

[codecov]

Codecov Report

Patch coverage: 7.69% and project coverage change: -0.02 ⚠️

Comparison is base (e0aaccf) 53.37% compared to head (e53bc57) 53.36%.

Additional details and impacted files

@@            Coverage Diff             @@
##               v2   #10369      +/-   ##
==========================================
- Coverage   53.37%   53.36%   -0.02%     
==========================================
  Files         104      104              
  Lines        8927     8939      +12     
==========================================
+ Hits         4765     4770       +5     
- Misses       3642     3648       +6     
- Partials      520      521       +1     

Impacted Files	Coverage Δ
pkg/compose/build.go	76.28% <0.00%> (-2.02%)	⬇️
pkg/compose/build_classic.go	52.91% <25.00%> (-0.86%)	⬇️

... and 1 file with indirect coverage changes

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[laurazard]

@glours PTAL :)

[ndeloof]

looks like we don't have coverage report for cucumber tests

[laurazard]

Yup, I was just realizing that. We probably need to do the -cover dance for those too?

[ndeloof]

yes we probably need GOCOVERDIR set somehow

[EronWright]

Heads-up, I hit upon an issue related to additional_contexts and relative paths.
#10448

Assumedly this is because the context is being passed uninterpreted by compose to buildx.

[ndeloof]

@EronWright according to the spec
https://github.com/compose-spec/compose-spec/blob/master/build.md

Validation beyond that is the responsibility of the image builder

but indeed, it would make sense we detect and expand relative paths. I'll investigate if this is feasible

[TeKa-Dev]

I have a problem with additional_contexts and directory paths containing a dot at the beginning:

additional_contexts:
  foo: /home/user/.bar/foo

it just comes out empty when COPY,
but it works on buildx:
docker buildx build . --build-context foo=/home/user/.bar/foo

[laurazard]

Hiya @TeKa-Dev,

I can't seem to reproduce this:

$ ls /home/laurabrehm/.config/nvim/
init.lua  lazy-lock.json  LICENSE  lua  README.md  stylua.toml

services:
  a:
    build:
        context: .
        additional_contexts:
          - dep=/home/laurabrehm/.config/nvim/

# syntax=docker/dockerfile:1
FROM alpine:latest
COPY --from=dep init.lua /

$ docker compose build
...
$ docker run --rm -it build-a sh
/ ls
...
init.lua

We might be able to help you if you provide a more complete reproduction scenario however.

[TeKa-Dev]

Hi, I was not accurate, not all directories with a dot cause the error, but .m2/repository/

$ docker buildx build . --build-context m2repository=/home/teka/.m2/repository/
[+] Building 1.1s (12/12) FINISHED
 => [internal] load build definition from Dockerfile                                                 0.0s
 => => transferring dockerfile: 994B                                                                 0.0s
 => [internal] load .dockerignore                                                                    0.0s
 => => transferring context: 34B                                                                     0.0s
 => resolve image config for docker.io/docker/dockerfile:1.4                                         0.9s
 => CACHED docker-image://docker.io/docker/dockerfile:1.4@sha256:9ba7531bd80fb0a858632727cf7a112fbf  0.0s
 => [internal] load build definition from Dockerfile                                                 0.0s
 => [internal] load .dockerignore                                                                    0.0s
 => [internal] load metadata for docker.io/library/alpine:latest                                     0.0s
 => [context m2repository] load .dockerignore                                                        0.0s
 => => transferring m2repository: 102B                                                               0.0s
 => [context m2repository] load from client                                                          0.0s
 => => transferring m2repository: 406.09kB                                                           0.0s
 => CACHED [stage-0 1/2] FROM docker.io/library/alpine:latest                                        0.0s
 => [stage-0 2/2] COPY --from=m2repository org /                                                     0.0s
 => exporting to image                                                                               0.0s
 => => exporting layers                                                                              0.0s
 => => writing image sha256:c9a3f6a8e9a2f369d8cb5332c0f4652d44e35c52e622d2fc899851a3b30c87ac         0.0s

services:
  alpine:
    build:
      context: .
      additional_contexts:
        - m2repository=/home/teka/.m2/repository/

$ docker-compose build
[+] Building 2.1s (11/11) FINISHED
 => [internal] load build definition from Dockerfile                                                 0.0s
 => => transferring dockerfile: 994B                                                                 0.0s
 => [internal] load .dockerignore                                                                    0.0s
 => => transferring context: 34B                                                                     0.0s
 => resolve image config for docker.io/docker/dockerfile:1.4                                         1.9s
 => CACHED docker-image://docker.io/docker/dockerfile:1.4@sha256:9ba7531bd80fb0a858632727cf7a112fbf  0.0s
 => [internal] load build definition from Dockerfile                                                 0.0s
 => [internal] load .dockerignore                                                                    0.0s
 => [internal] load metadata for docker.io/library/alpine:latest                                     0.0s
 => [context m2repository] load .dockerignore                                                        0.0s
 => => transferring m2repository: 2B                                                                 0.0s
 => [context m2repository] load from client                                                          0.0s
 => => transferring m2repository: 2B                                                                 0.0s
 => [stage-0 1/2] FROM docker.io/library/alpine:latest                                               0.0s
 => ERROR [stage-0 2/2] COPY --from=m2repository org /                                               0.0s
------
 > [stage-0 2/2] COPY --from=m2repository org /:
------
failed to solve: failed to compute cache key: "/org" not found: not found

I don't know if this is related but it doesn't work for me

$ docker compose build
services.alpine.build Additional property additional_contexts is not allowed

I use

$ docker -v
Docker version 20.10.23, build 7155243
$ docker-compose -v
Docker Compose version v2.17.2