Fix Version Output For Automated Container Builds

[seanmalloy]

Prior to this change the output from the command "descheduler version" when run using the official container images from k8s.gcr.io would always output an empty string. See below for an example.

docker run k8s.gcr.io/descheduler/descheduler:v0.19.0 /bin/descheduler version
Descheduler version {Major: Minor: GitCommit: GitVersion: BuildDate:2020-09-01T16:43:23+0000 GoVersion:go1.15 Compiler:gc Platform:linux/amd64}

This change makes it possible to pass the descheduler version information to the automated container image build process and also makes it work for local builds too.

Fixes #425

[seanmalloy]

Not quite done testing yet.

/hold

[seanmalloy]

Here is what the new output for descheduler version looks like after this change.

Example for local builds and automated builds using a commit(not a tag):

$ make build
CGO_ENABLED=0 go build -ldflags "-X sigs.k8s.io/descheduler/cmd/descheduler/app.version=v20201013-v0.18.0-181-g7ae3f9ea2 -X sigs.k8s.io/descheduler/cmd/descheduler/app.buildDate=2020-10-13T22:28:24-0500" -o _output/bin/descheduler sigs.k8s.io/descheduler/cmd/descheduler
$ ./_output/bin/descheduler version
Descheduler version {Major:0 Minor:18+ GitVersion:v20201013-v0.18.0-181-g7ae3f9ea2 BuildDate:2020-10-13T22:28:24-0500 GoVersion:go1.15.2 Compiler:gc Platform:darwin/amd64}

Example for automated builds using a tag:

$ VERSION=v20200521-v0.18.0 make build
CGO_ENABLED=0 go build -ldflags "-X sigs.k8s.io/descheduler/cmd/descheduler/app.version=v20200521-v0.18.0 -X sigs.k8s.io/descheduler/cmd/descheduler/app.buildDate=2020-10-13T22:35:46-0500" -o _output/bin/descheduler sigs.k8s.io/descheduler/cmd/descheduler
$ ./_output/bin/descheduler version
Descheduler version {Major:0 Minor:18+ GitVersion:v20200521-v0.18.0 BuildDate:2020-10-13T22:35:46-0500 GoVersion:go1.15.2 Compiler:gc Platform:darwin/amd64}

Example for automated builds using the helm chart tag. Yes, this is still broken:

$ VERSION=v20201012-descheduler-helm-chart-0.19.0-39-gb33928ac9 make build
CGO_ENABLED=0 go build -ldflags "-X sigs.k8s.io/descheduler/cmd/descheduler/app.version=v20201012-descheduler-helm-chart-0.19.0-39-gb33928ac9 -X sigs.k8s.io/descheduler/cmd/descheduler/app.buildDate=2020-10-13T22:37:09-0500" -o _output/bin/descheduler sigs.k8s.io/descheduler/cmd/descheduler
$ ./_output/bin/descheduler version
Descheduler version {Major: Minor: GitVersion:v20201012-descheduler-helm-chart-0.19.0-39-gb33928ac9 BuildDate:2020-10-13T22:37:09-0500 GoVersion:go1.15.2 Compiler:gc Platform:darwin/amd64}

[seanmalloy]

/test pull-descheduler-verify-master

[seanmalloy]

/assign @damemi
/cc @ingvagabund @lixiang233

[seanmalloy]

/hold cancel

[seanmalloy]

Also, tested the make image target.

$ make image
docker run descheduler:v20201014-v0.18.0-181-gcf020224a /bin/descheduler version
Descheduler version {Major:0 Minor:18+ GitVersion:v20201014-v0.18.0-181-gcf020224a BuildDate:2020-10-14T06:06:27+0000 GoVersion:go1.15.2 Compiler:gc Platform:linux/amd64}

and ...

$ VERSION=v20200521-v0.18.0 make image
$ docker run descheduler:v20200521-v0.18.0 /bin/descheduler version
Descheduler version {Major:0 Minor:18+ GitVersion:v20200521-v0.18.0 BuildDate:2020-10-14T06:11:35+0000 GoVersion:go1.15.2 Compiler:gc Platform:linux/amd64}

[damemi]

@seanmalloy looks like you've got it working, but as you mentioned in #427 (comment) this is obviously still going to print the wrong tag for automatic builds. So 2 questions: that shouldn't be a problem with images pulled from the published v0.19.0 tags right? And also, would there be a way to parse the semver out of the helm-chart tag and use that?

[seanmalloy]

@damemi see responses to your questions below.

that shouldn't be a problem with images pulled from the published v0.19.0 tags right?

Short answer, correct.

I believe once this PR is merged the descheduler version command will print the correct version information for the container images that are built for releases. I think the only gotcha when creating a release is that you must create and push the git tag prior to creating the release in the GitHub UI. Maybe someday there will be a shell script to automate the few manual release steps.

And also, would there be a way to parse the semver out of the helm-chart tag and use that?

My concern would be that we would be putting in helm chart version into the descheduler binary instead of the descheduler version. Let me know if you disagree.

I don't have a great solution for this right now.

[damemi]

@seanmalloy cool, I actually think the recent updates we made to the chart releaser action might fix our automatic releases (the new version of the action tags from the branch it's created from, which will keep it separate from master see #436 (review)).

I think the only gotcha when creating a release is that you must create and push the git tag prior to creating the release in the GitHub UI.

Also btw, the tags can be created from the github UI when you create the release (this is how I've done the past couple releases 😉)

[damemi]

@seanmalloy this looks good to me if you just squash the commits
/approve
/hold
@ingvagabund can lgtm (and remove the hold)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[seanmalloy]

I'll squash commits after @ingvagabund reviews assuming there are not additional changes requested.

[ingvagabund]

Looks good, you can squash. I will lgtm right after. Thanks!!!

[seanmalloy]

@ingvagabund commits have been squashed.

[ingvagabund]

/lgtm
/hold cancel