I don't understand how this even works... surely when entering the container it tries to build something that it doesn't know about?

What don't you understand? It simply names the binary based on the host
architecture/OS (for which it's also compiled).

It fixes trying to use a binary from the wrong architecture when mixing
builds in and out of the container (e.g. in an OSX host) which was being
experienced by @davkal.

From a conversation in Slack it seems @davkal may be having other problems
too, let's see if this helps.

On Wednesday, February 24, 2016, Tom Wilkie [email protected]
wrote:

I don't understand how this even works... surely when entering the
container it tries to build something that it doesn't know about?

—
Reply to this email directly or view it on GitHub
#1028 (comment).

Builds in container, and on Darwin. LGTM

Pls hold off on this until I've had a chance to look at it, I have some concerns.

I get this when trying to build using docker-machine on my mac:

docker run --rm -ti \
        -v /Users/twilkie/Documents/src/github.com/weaveworks/scope:/go/src/github.com/weaveworks/scope \
        -v /Users/twilkie/Documents/src/github.com/weaveworks/scope/.pkg:/go/pkg \
        --net=host \
        -e GOARCH -e GOOS -e CIRCLECI -e CIRCLE_BUILD_NUM -e CIRCLE_NODE_TOTAL \
        -e CIRCLE_NODE_INDEX -e COVERDIR -e SLOW \
        weaveworks/scope-backend-build SCOPE_VERSION=18964aa GO_BUILD_INSTALL_DEPS=-i vendor/github.com/ugorji/go/codec/codecgen/bin/codecgen_darwin_amd64
make: Entering directory '/go/src/github.com/weaveworks/scope'
make: *** No rule to make target 'vendor/github.com/ugorji/go/codec/codecgen/bin/codecgen_darwin_amd64'.  Stop.
make: Leaving directory '/go/src/github.com/weaveworks/scope'
make: *** [vendor/github.com/ugorji/go/codec/codecgen/bin/codecgen_darwin_amd64] Error 2

@tomwilkie please take another look. I fixed it by moving all the codecgen dependencies to the non-containerized part (which is here they should be since codecgen depends on the host of whatever runs the non-containerized part)

This now requires I have go installed, which I thought we'd decided against...

This now requires I have go installed, which I thought we'd decided against...

No it doesn't. Have you actually tested it?

As I already said, the makefile variables are used lazily unless assigned with :=, although I can happily define the variable in the non-containerized-block if that's confusing.

vagrant@vagrant-ubuntu-vivid-64:~/scope$ echo $PATH
/home/vagrant/bin:/usr/local/go/bin:/home/vagrant/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
vagrant@vagrant-ubuntu-vivid-64:~/scope$ export PATH=/home/vagrant/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
vagrant@vagrant-ubuntu-vivid-64:~/scope$ which go
vagrant@vagrant-ubuntu-vivid-64:~/scope$ make

@2opremio how did you test the darwin build? Which command do you run?

@davkal I have been relying on you to test the build in Darwin (I use a Linux VM). The purpose of this PR is to make you comfortable with the build, hence the PTAL :)

This command used to work make report/report.codecgen.go (on my mac, building in a container) but now does not.

Also, if I change the build container the .codecgen.go files are not rebuilt and I kinda think they should be.

In general it makes me uncomfortable to have different dependancy trees inside the container to outside.

Note both of these are minor issues. What precisely is the problem we're trying to solve here?

I cant think of a nicer way of doing this, so assuming we still want to fix the build-in-container-then-build-on-a-mac-without-a-make-clean-inbetween problem, I'm LGTM.

@davkal / @foot You would still like to have this, right?

Yes please, easier it is to build in and out of container the better!

Yes please, easier it is to build in and out of container the better!

Alright, then I will rebase the changes and ask you to take another look

Rebased.

@foot Can you please test it so that we can merge it? (Ideally before it bit-rots again! :) )

env -u doesn't work on osx! grrr.
Linux: env -u GOARCH -u GOOS $(GO)
Darwin equiv: unset GOARCH GOOS; $(GO)

• Made a quick patch for the above.
• I also made a mess when rebasing onto master, i think i fixed it though, look okay?
• I have a new file now: vendor/github.com/ugorji/go/codec/codecgen/codecgen, should this be gitignored?

But otherwise it works nicely!

Rebased onto master.

But circle is giving a funny permission error now so maybe i broke something..

I have a new file now: vendor/github.com/ugorji/go/codec/codecgen/codecgen, should this be gitignored?

That's because we now build vendor/github.com/ugorji/go/codec/codecgen/codecgen_OS_ARCH instead. Just remove the file manually (you will only need to do this once).

I think we were overcomplicating it. My last commit makes it much simpler (although it will only work when ugorji/go#148 is merged and we bump the dependency).

• Get rid of GO15VENDOREXPERIMENT since it's enabled by default in Go >=1.6,
  just use go 1.6 if you want to build outside the container.
• Stop using unset/env -u, just avoid adding env variables where needed.
• Pass build flags consistently to codecgen.
• Let the experimental/ directory be.

LGTM for me!