Well… it’s been a minute since I wrote anything here. Sometimes life gets busy ;)
Much of my time recently has been spent learning about the Kubernetes Cluster API project. I have recently changed roles within Red Hat and I am now spenting much more time on the core layers of Kubernetes and less time on machine learning related activities.
To get started on the project, I needed to start building the main components and one in specific that I want to become proficient with is the Kubernetes autoscaler project. I run Fedora Linux as my primary desktop operating system and the autoscaler requires the Go language tooling, easy enough or so I thought…
The main autoscaler instructions about
Getting the Code
are pretty clear and in no time I was able to get
make build working. But
I had seen a colleague running individual tests out of the source tree using
the Go tooling directly and I needed to know how to do this!
I switch to the feature branch I want and descend into the
cloudprovider/openshiftmachineapi directory to run the tests.
$ go test go: firstname.lastname@example.org: parsing /tmp/ca-update-vendor.8g82/kubernetes/staging/src/k8s.io/api/go.mod: open /tmp/ca-update-vendor.8g82/kubernetes/staging/src/k8s.io/api/go.mod: no such file or directory
hmm… that error looks kinda weird. What is happening that is causing Go to
/tmp for stuff? I check the
go.mod file and do see something about a
bunch of Kubernetes modules that should be in
/tmp. This is confusing.
After searching through several
Makefiles, double checking my sanity, and
reading the script files in the
hack directory of the repository I finally
start to see what is going on with the temporary directory. There is a script
update-vendor.sh in the
cluster-autoscaler/hack directory that
has several commands about processing the Kubernetes module dependencies and
then creating a vendor directory in
/tmp. Ok, this is making some sense but
how do I run the Go tools!
I talked with the colleague who had initially shown me this code and we
compared notes about development environments. It turns out that the ultimate
solution to my woes is uising the
-mod=vendor command when running the tests.
And in fact, with this in place I can now run these commands:
$ go test -mod=vendor W0302 15:21:19.296483 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-0" has no providerID W0302 15:21:19.296542 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-1" has no providerID W0302 15:21:19.296551 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-2" has no providerID W0302 15:21:19.497661 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-1" has no providerID W0302 15:21:19.497709 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-2" has no providerID W0302 15:21:19.497727 504379 machineapi_controller.go:359] Machine "test-namespace-machineset-0-machine-0" has no providerID PASS ok k8s.io/autoscaler/cluster-autoscaler/cloudprovider/openshiftmachineapi 11.667s
yay! I can start working on this thing =)
According to the documentation,
The -mod build flag provides additional control over updating and use of go.mod.
If invoked with -mod=vendor, the go command assumes that the vendor directory holds the correct copies of dependencies and ignores the dependency descriptions in go.mod.
what I gather this to mean is that all the fancy vendoring of Kubernetes that is done must be handled automatically by flags in the Makefiles when building and testing. I suppose the vendoring that is happening is actually using some sort of staged or fixed version of Kubernetes that the module tooling has issues with. Regardless, this flag allows me to easily continue on my journey.
If I wanted to go further I could set this flag in my
export GOFLAGS="-mod=vendor", but I’m not sure if there are unintended
consequences to that action. I’m happy to have this stuff working, and perhaps
next time I will cover how to run it against a cluster.
take care, and happy hacking!