SKIP_DOCKER=true make build still attempts to use Docker for Darwin build

[radu-matei]

$ export SKIP_DOCKER=true
$ make build
bash -c "LDFLAGS=\"-w -s -X github.com/cnabio/duffle/pkg/version.Version=2fc6ad7\" scripts/build.sh"
building linux-amd64
building windows-amd64
building darwin-amd64
docker build \
        -t duffle:2fc6ad7 \
        --build-arg LDFLAGS='-w -s -X github.com/cnabio/duffle/pkg/version.Version=2fc6ad7' \
        .
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
Makefile:110: recipe for target 'build-image' failed
make: *** [build-image] Error 1

cc @krancour

[krancour]

@radu-matei

I believe this is doing what it is supposed to. The build target is defined as follows:

build: build-all-bins build-image

The pre-req build-all-bins target is happening outside of Docker:

bash -c "LDFLAGS=\"-w -s -X github.com/cnabio/duffle/pkg/version.Version=2fc6ad7\" scripts/build.sh"

The pre-req build-image target is a different story. It's building a Docker image-- which cannot be accomplished without docker build (unless you want to bring something like kaniko into the mix).

SKIP_DOCKER=true really only stops things that can be done without Docker from being done without Docker. Building an image isn't one of those things.