Fix bug in apiserver service cidr split

[darshanime]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Fix bug where kube-apiserver would fail to start when not providing service CIDR

Which issue(s) this PR fixes:
NA

Special notes for your reviewer:
The strings.Split documentation states:

// If s does not contain sep and sep is not empty, Split returns a
// slice of length 1 whose only element is s.

import (
	"fmt"
	"strings"
)

func main() {
	serviceClusterIPRanges := ""
	serviceClusterIPRangeList := strings.Split(serviceClusterIPRanges, ",")
	fmt.Printf("len: %d, value: %+v", len(serviceClusterIPRangeList), serviceClusterIPRangeList)

}

// Output
// len: 1, value: []

playground link

This would fail the if check here and apiserver wouldn't start. This PR fixes this bug.

Does this PR introduce a user-facing change?:
NA

Release note:

NONE

[k8s-ci-robot]

Hi @darshanime. 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.

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[BenTheElder]

/ok-to-test

[BenTheElder]

/sig network

[BenTheElder]

/lgtm

[aojea]

/assign @thockin @khenidak
/priority important-soon

[aojea]

thanks
/lgtm

[justaugustus]

@darshanime -- This needs a release note.

[liggitt]

Also needs a test

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[darshanime]

@liggitt, I have removed the default ServiceClusterIPRanges from the testServer used thruout the codebase since it is deprecated.
Everything passes still, is this enough? Or should I write a separate test for the app.Complete func?

[liggitt]

Don't change the integration test setup.

It would be better to have the ServiceClusterIPRanges -> serviceIP, serviceIPRange, secondaryServiceIPRange, error logic in a standalone function that could be unit tested easily, and then used like this in Complete():

apiServerServiceIP, serviceIPRange, secondaryServiceIPRange, err := getServiceIPAndRanges(s.ServiceClusterIPRanges)
if err != nil {
  return options, err
}
s.PrimaryServiceClusterIPRange = serviceIPRange
s.SecondaryServiceClusterIPRange = secondaryServiceIPRange

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: darshanime
To complete the pull request process, please assign liggitt
You can assign the PR to them by writing /assign @liggitt in a comment when ready.

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

Needs approval from an approver in each of these files:

• cmd/kube-apiserver/OWNERS

Approvers can indicate their approval by writing /approve in a comment
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[darshanime]

@liggitt thanks for the review. Please take a look now.

[liggitt]

need to run hack/update-bazel.sh to pick up the new test file:

diff --git a/cmd/kube-apiserver/app/BUILD b/cmd/kube-apiserver/app/BUILD
index 66570c567e5..95162cf8760 100644
--- a/cmd/kube-apiserver/app/BUILD
+++ b/cmd/kube-apiserver/app/BUILD
@@ -1,4 +1,4 @@
-load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
 
 go_library(
     name = "go_default_library",
@@ -99,3 +99,9 @@ filegroup(
     tags = ["automanaged"],
     visibility = ["//visibility:public"],
 )
+
+go_test(
+    name = "go_default_test",
+    srcs = ["server_test.go"],
+    embed = [":go_default_library"],
+)

lgtm otherwise, much better tested, thanks!

[liggitt]

2019 in new files

[k8s-ci-robot]

@darshanime: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-e2e-gce	2c64a45	link	/test pull-kubernetes-e2e-gce
pull-kubernetes-verify	2c64a45	link	/test pull-kubernetes-verify

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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.

[liggitt]

comments resolved in #85968

[liggitt]

/close
in favor of #85968

[k8s-ci-robot]

@liggitt: Closed this PR.

In response to this:

/close
in favor of #85968

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.

[darshanime]

Hi @liggitt, sorry I was asleep, it was already 1am IST here 😴
Thanks for reviewing this 🙏