Fix build

[friism]

- What I did

make build doesn't work, so I fixed it. There were two problems:

• source is not in sh on Ubuntu: http://stackoverflow.com/a/13702876/2942
• CGO_ENABLED was not set in the scripts invoked from the makefile

- How to verify it

make build

[dnephin]

I believe this is also fixed by #78 which includes some other stuff for cross.

[dnephin]

I think CGO_ENABLED is already set in the Dockerfiles, no?

[friism]

Yes, but these scripts are invoked from make outside the Dockerfiles too so builds not using Docker won't work without this setting.

[dnephin]

True, this is also fixed in #78

[friism]

Cool @dnephin do you want me to remove that change from this pr?

[friism]

I believe this is also fixed by #78 which includes some other stuff for cross.

@dnephin that PR adds bash as a requirement which means the build won't work in builds in standard alpine-based containers. Using bash in the shebang was also my first impulse, but I found that caused the Docker-based build to fail.

[dnephin]

Sure, it's also going to fail in any container that doesn't have go, or sh. Why would it run in any container but the one we've defined in this repo? My change adds bash to the Dockerfile.

[friism]

It would run outside of a container (in my case on Ubuntu). That's the primary documented way to build the project: https://github.com/docker/cli#build-locally

Solving the problem by removing dependencies and complexity rather than piling more on top seems preferable.

[dnephin]

bash exists on ubuntu, so why would it fail when using bash?

We should also fix those instructions. I don't think running outside a container should be recommended.

[friism]

@dnephin it wouldn't fail on Ubuntu when using bash, but you didn't answer my question: Why solve the problem by adding more complexity rather than removing complexity?

[dnephin]

You didn't answer my question either! You said it would fail on alpine images, and I was asking why we would support arbitrary images!

I agree we should keep dependencies to a minimum. I don't think bash is an unreasonable dependency. We need to use bash to support -o pipefail anyway, so it's not an optional dependency.

I don't see either option are more complex. Where is the additional complexity?