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.

[k8s-ci-robot]

Thanks for your pull request. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please follow instructions at https://git.k8s.io/community/CLA.md#the-contributor-license-agreement to sign the CLA.

It may take a couple minutes for the CLA signature to be fully registered; after that, please reply here with a new comment and we'll verify. Thanks.

---

• If you've already signed a CLA, it's possible we don't have your GitHub username or you're using a different email address. Check your existing CLA data and verify that your email is set on your git commits.
• If you signed the CLA as a corporation, please sign in with your organization's credentials at https://identity.linuxfoundation.org/projects/cncf to be authorized.
• If you have done the above and are still having issues with the CLA being reported as unsigned, please log a ticket with the Linux Foundation Helpdesk: https://support.linuxfoundation.org/
• Should you encounter any issues with the Linux Foundation Helpdesk, send a message to the backup e-mail support address at: [email protected]

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[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

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: myhro
To fully approve this pull request, please assign additional approvers.
We suggest the following additional approver: tstromberg

If they are not already assigned, you can assign the PR to them by writing /assign @tstromberg in a comment when ready.

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[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. :-)