test: add test for global DNS configuration

[mkowalski]

Is this a BUG FIX or a FEATURE ?:

/kind enhancement

What this PR does / why we need it:

Special notes for your reviewer:

Release note:

NONE

[mkowalski]

/test pull-kubernetes-nmstate-unit-test

It may be a valid issue

 /home/prow/go/pkg/mod/github.com/golangci/golangci-lint@v1.55.2/pkg/golinters/musttag.go:4:2: unrecognized import path "go.tmz.dev/musttag": reading https://go.tmz.dev/musttag?go-get=1: 404 Not Found 

[cathay4t]

Not sure related or not. It is known that nmstate will always use global DNS for:

---
dns-resolver:
  config:
    server:
    - 2001:4860:4860::8888
    - 8.8.8.8
    - 2606:4700:4700::1111

With a rollback triggered by bad config, you may verify whether global DNS is reverted or not. Of course, you need mark it as known to be fail.

[mkowalski]

But those servers are good, so they will not trigger the revert. If I read the current code correctly, we want the test to contain hardcoded wrong DNS server, that's why I used 192.168.100.3

[mkowalski]

/retest

[mkowalski]

/test pull-kubernetes-nmstate-unit-test

[mkowalski]

/retest

[mkowalski]

/hold

This test is expected to fail until we have NM fixed. Currently it configures 192.168.100.3 (fake) and never rolls it back

Handler E2E Test Suite: [It] rollback when name servers (configured globally) are wrong after state configuration should rollback to previous name servers expand_less 	14m8s
{Timed out after 480.000s.
should eventually lose wrong name server
Expected
    <[]string | len:1, cap:1>: ["192.168.100.3"]
not to contain element matching
    <string>: 192.168.100.3 failed [FAILED] Timed out after 480.000s.
should eventually lose wrong name server
Expected
    <[]string | len:1, cap:1>: ["192.168.100.3"]
not to contain element matching
    <string>: 192.168.100.3
In [It] at: /tmp/knmstate/kubernetes-nmstate/test/e2e/handler/rollback_test.go:262 @ 02/03/24 21:59:26.922
}

[mkowalski]

/retest

[mkowalski]

/retest

go: downloading golang.org/x/mod v0.4.2
/home/prow/go/pkg/mod/k8s.io/apimachinery@v0.23.0/pkg/api/resource/amount.go:23:2: unrecognized import path "gopkg.in/inf.v0": reading https://gopkg.in/inf.v0?go-get=1: 502 Bad Gateway
	server response: Cannot obtain refs from GitHub: timeout
/home/prow/go/pkg/mod/sigs.k8s.io/structured-merge-diff/v4@v4.1.2/value/value.go:26:2: unrecognized import path "gopkg.in/yaml.v2": reading https://gopkg.in/yaml.v2?go-get=1: 502 Bad Gateway
	server response: Cannot obtain refs from GitHub: timeout
/home/prow/go/pkg/mod/sigs.k8s.io/controller-tools@v0.8.0/pkg/schemapatcher/gen.go:24:2: unrecognized import path "gopkg.in/yaml.v3": reading https://gopkg.in/yaml.v3?go-get=1: 502 Bad Gateway
	server response: Cannot obtain refs from GitHub: timeout
make: *** [Makefile:134: gen-k8s] Error 1

[mkowalski]

/retest

[qinqon]

/retest

[qinqon]

/lgtm
/approve

[kubevirt-bot]

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[mkowalski]

/retest

[mkowalski]

/hold cancel

That should actually work