Add Go modules support

[myhro]

Moving away from Go dep to Go modules allowed the build infrastructure to be cleaned up a bit. The related docs were also updated.

The whole diff is somewhat long after the vendor/ directory removal, so I guess reviewing it per commit can make the process a bit easier.

This closes #4234.

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[k8s-ci-robot]

Hi @myhro. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[minikube-bot]

Can one of the admins verify this patch?

[afbjorklund]

"Somewhat" (2,178 files, +323 −929,569 lines)

[myhro]

I signed it

[myhro]

/assign @tstromberg

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[tstromberg]

@minikube-bot OK to test

[tstromberg]

This change looks beautiful. Once the integration tests are run, I'll merge it.

[myhro]

Thank you for the review. Jenkins build is broken, I'll investigate how to fix it.

[tstromberg]

@myhro - We do something funny and build the kvm2 driver binary from inside a Docker image running an older release of Debian for libvirt compatibility.

Let me or @sharifelgamal know if you need any help in getting with getting this sorted out.

[myhro]

@tstromberg The kvm2 driver build system I found quite clever and was able to fix it by adding git to its Docker image. jteeuwen/go-bindata is a tool I would like to replace, as it is not maintained anymore, but right now I don't have an alternative for it.

Debugging the last failure, I noticed that it was trying to build the hyperkit driver under the karalabe/xgo-1.10.x image which, as the name suggests, is based on Go 1.10, a version that doesn't support modules. I've changed it to karalabe/xgo-1.12.x and was able to build the driver with:

MINIKUBE_BUILD_IN_DOCKER=y make out/docker-machine-driver-hyperkit

Now I see that it still failed on Jenkins, so I'll keep digging.

[myhro]

@tstromberg Sorry, I only saw that after sending the last comment:

Status: Downloaded newer image for karalabe/xgo-1.12.x:latest
docker: Error response from daemon: devmapper: Thin Pool has 148835 free data
blocks which is less than minimum required 163840 free data blocks. Create more
free space in thin pool or use dm.min_free_space option to change behavior.
See 'docker run --help'.
Makefile:282: recipe for target 'out/docker-machine-driver-hyperkit' failed
make: *** [out/docker-machine-driver-hyperkit] Error 125

Did the Jenkins builder run out of disk space?

P.s.: I can join Slack if you prefer to avoid the comment ping-pong.

[tstromberg]

I found https://stackoverflow.com/questions/47457012/how-to-increase-the-space-data-space-total-used-by-docker-that-value-is-less - which mentioned running "docker system prune". Going to do so on our Jenkins master, which apparently has hundreds of old images around:

sudo docker system df

TYPE                TOTAL               ACTIVE              SIZE                RECLAIMABLE
Images              434                 0                   66.97GB             66.97GB (100%)
Containers          0                   0                   0B                  0B
Local Volumes       0                   0                   0B                  0B

[tstromberg]

@minikube-bot OK to test

[tstromberg]

It looks like perhaps a merge is in order, since jibber jabber is a recent addition? Jenkins got farther this time: passing the hyperkit build, but failing kvm2:

15:16:39 pkg/minikube/constants/constants.go:27:2: cannot find package "github.com/blang/semver" in any of:
15:16:39 	/usr/local/go/src/github.com/blang/semver (from $GOROOT)
15:16:39 	/var/lib/jenkins/go/src/github.com/blang/semver (from $GOPATH)
15:16:39 pkg/minikube/console/console.go:27:2: cannot find package "github.com/cloudfoundry-attic/jibber_jabber" in any of:
...
15:16:39 	/usr/local/go/src/k8s.io/kubernetes/cmd/kubeadm/app/constants (from $GOROOT)
15:16:39 	/var/lib/jenkins/go/src/k8s.io/kubernetes/cmd/kubeadm/app/constants (from $GOPATH)
15:16:39 Makefile:345: recipe for target 'out/docker-machine-driver-kvm2' failed
15:16:39 make: *** [out/docker-machine-driver-kvm2] Error 1
15:16:39 make: *** Waiting for unfinished jobs....

[tstromberg]

Here's the PR that added jibber jabber 7 days ago: #4199

[myhro]

Thanks for fixing the disk space issue. The out/docker-machine-driver-kvm2 task is failing because Go modules aren't available. As it doesn't runs under Docker, different than the hyperkit one, and it's a straight call to go build, I suspect that the Jenkins builder has Go < 1.12 currently installed. I can't confirm that suspicion, as the Go version information isn't available in the build logs.

I'm seeing two possible solutions for this problem:

• We can consider that every driver has to be built under Docker, changing out/docker-machine-driver-kvm2 to behave like out/docker-machine-driver-hyperkit.
• Confirm the Go version hypothesis and, if it's true, update the Jenkins builder to use an up-to-date Go version.

Which one you prefer?

Edit: actually we need Go 1.12. I've seen some problems building the project under 1.11.

[tstromberg]

go v1.12 is a requirement, as per https://github.com/kubernetes/minikube/blob/master/docs/contributors/build_guide.md

I did notice that the Jenkins master was stuck on go v1.12rc1, so I've upgraded the master to v1.12.5. I'm having similar issues building locally, and I believe the difference between our environments is that Jenkins and myself are building from ~/go/src, which disables go modules by default.

I believe that this PR will need to do is set env GO111MODULE=on in the Makefile to guarantee
build consistency across environments. I would rather not Docker become a build dependency unless strictly necessary.

[tstromberg]

If possible, leave this at 1.x so that we will continue to auto-update when v1.13 comes along.

[myhro]

Done.

[tstromberg]

Thank you for taking this beast of a PR on, by the way. I just learned today that a tool we would like to use for localization (golang.org/x/text/cmd/gotext) is incompatible with vendor directories, so this PR is perfectly timed. You are a hero =)

[tstromberg]

@minikube-bot OK to test

[myhro]

Thank you for clarifying the version and upgrading the server. I agree that it makes way more sense to use GO111MODULE=on and not worry about the import path anymore. I still removed it from the .travis.yml file just to be clear that it's not needed.

I just learned today that a tool we would like to use for localization (golang.org/x/text/cmd/gotext) is incompatible with vendor directories, so this PR is perfectly timed.

I didn't knew that there were projects incompatible with vendor directories. Thanks for the tip. I'm glad that we are taking care of that detail. :-)

I'm a bit confused, as there are no timestamps in the Jenkins logs, but looks like the build worked and the integration tests are running now.

[tstromberg]

Looks like the build works great with the most recent changes.

I'll wait for the rest of the integration tests to pass, and then merge it in. Thank you again!

[tstromberg]

Huzzah! 🎉 Thank you!

[myhro]

That's great. Thank you very much for your support, Thomas. It would be way harder without it.

Hope we can work together again on other features/PRs. :-)