fix dockerfile to build correct go binary

[arnopensource]

Removed 2 superfluous lines from docker/Dockerfile.multiarch that caused undefined environment variables in the Makefile which caused amd64 go builds in all cases

More details on woodpecker-ci/woodpecker#1443

[lafriks]

Why is ARG HOME removed?

[arnopensource]

Because it is still at line 11

Since the duplicated line for TARGEOS and TARGETARCH created a bug I though it was the same for HOME

I didn't test it though, I will do it now

[arnopensource]

Ok I searched a little but I have no idea how the HOME arg should be used :/
And I just realized that I deleted the default value (/app) of the argument

Any help on the subject would be appreciated

[lafriks]

@6543 can you help on this?

[anbraten]

Have a look at https://docs.docker.com/engine/reference/builder/#understand-how-arg-and-from-interact

From reading the buildx docs again I would confirm that TARGETOS, ... is directly passed by buildx. It then can be used inside the dockerfile / build run process. I guess setting it above FROM will override the values passed by buildx.

[anbraten]

For home I would just add the default to the lower arg home line.

[arnopensource]

I spent some time in the docs to understand the arguments coming from buildx and their scopes, see:

• https://docs.docker.com/engine/reference/builder/#automatic-platform-args-in-the-global-scope for an explanation of where the args come from
  Note:

  These arguments are defined in the global scope so are not automatically available inside build stages or for your RUN commands. To expose one of these arguments inside the build stage redefine it without value.

• https://docs.docker.com/engine/reference/builder/#scope for an explanation of the scope of the args
• https://docs.docker.com/build/building/multi-stage/#use-multi-stage-builds an explanation of what a build stage is (build stages are used to define the scope of an arg)

Same conclusion as @anbraten :

• declaring TARGETOS and TARGETARCH in the global scope was overriding the values coming from buildx
• we should be fine using only the ARG HOME in the relevant build step since it is only used here, I will add the default value that I accidentally deleted

Since the ARG HOME is not at the top of the file anymore, it is less visible. I could maybe add a line in the README.md about it ?

[6543]

hah that it was - thanks ❤️