Add network and target to build in v3.4

[dnephin]

Fixes #305
Related docker/compose#5011

This is basically a no-op, but it's good to keep them synced, and it will work when Compose uses the v3.4 schema.

[codecov-io]

Codecov Report

Merging #430 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #430   +/-   ##
=======================================
  Coverage   46.28%   46.28%           
=======================================
  Files         194      194           
  Lines       16134    16134           
=======================================
  Hits         7467     7467           
  Misses       8278     8278           
  Partials      389      389

[vdemeester]

LGTM 🐯

[sirlatrom]

Seeing as multi-stage builds with targets were introduced as part of docker-ce stable 17.06, is there any chance this change will be part of any 17.06.x stable patch release?

[thaJeztah]

LGTM

[thaJeztah]

@sirlatrom docker stack deploy doesn't support build, so for the docker 17.06 release there's nothing to do; an update to docker compose could support it, but that's a separate repository

[dnephin]

cc @shin- just an FYI that we've added these to v3.4

[sirlatrom]

@thaJeztah docker stack deploy doesn't support the services.service.build key, but it does validate its contents, giving errors like shown below. While that is the case, the same docker-compose.yml cannot be used for both building the images and deploying the stack.

app.go:

package main
func main() {
}

Dockerfile:

FROM golang:1.7.3 as builder
WORKDIR /go/src/github.com/alexellis/href-counter/
RUN go get -d -v golang.org/x/net/html
COPY app.go    .
RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o app .

FROM alpine:latest
RUN apk --no-cache add ca-certificates
WORKDIR /root/
COPY --from=builder /go/src/github.com/alexellis/href-counter/app .
CMD ["./app"]

docker-compose.yml:

version: '3.3'
services:
    builder:
        build:
            context: .
            target: builder
    app:
        build:
            context: .

Error message:

$ docker stack deploy --compose-file docker-compose.yml mystack
services.builder.build Additional property target is not allowed

$ docker version
Client:
 Version:      17.06.0-ce
 API version:  1.30
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:23:31 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.06.0-ce
 API version:  1.30 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:19:04 2017
 OS/Arch:      linux/amd64
 Experimental: false