🐛 handle nil pointer in clusterctl describe

[bavarianbidi]

What this PR does / why we need it:

if a cluster as an empy bootstrap.configref in the machinedeployment (which is allowed), a nil pointer will raise if clusterctl describe cluster is called with --show-templates.

Also add a second type of a fake machinedeployment which has a secret reference in the boostrap object instead of a config ref

/*
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x40 pc=0x19478c0]

goroutine 1 [running]:
sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree.ObjectReferenceObject(0x0)
        sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree/util.go:116 +0x40
sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree.addMachineDeploymentToObjectTree({0x2153e90, 0xc000120008}, {0x215ebf8, 0xc0002ca770}, 0xc000c336c0, 0xc000c336c0?, 0x2171100?, 0xc0009e2200, {{0x7fffd7f57514, 0x3}, ...}, ...)
        sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree/discovery.go:244 +0x35b
sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree.Discovery({0x2153e90, 0xc000120008}, {0x215ebf8?, 0xc0002ca770?}, {0x7fffd7f574f3, 0xe}, {0x7fffd7f574eb, 0x4}, {{0x7fffd7f57514, 0x3}, ...})
        sigs.k8s.io/cluster-api/cmd/clusterctl/client/tree/discovery.go:145 +0x94c
sigs.k8s.io/cluster-api/cmd/clusterctl/client.(*clusterctlClient).DescribeCluster(0x0?, {{{0x0, 0x0}, {0x0, 0x0}}, {0x7fffd7f574f3, 0xe}, {0x7fffd7f574eb, 0x4}, {0x7fffd7f57514, ...}, ...})
        sigs.k8s.io/cluster-api/cmd/clusterctl/client/describe.go:91 +0x218
sigs.k8s.io/cluster-api/cmd/clusterctl/cmd.runDescribeCluster(0x0?, {0x7fffd7f574eb, 0x4})
        sigs.k8s.io/cluster-api/cmd/clusterctl/cmd/describe_cluster.go:154 +0x1d8
sigs.k8s.io/cluster-api/cmd/clusterctl/cmd.glob..func6(0x31aae60?, {0xc00018af80?, 0x8?, 0x8?})
        sigs.k8s.io/cluster-api/cmd/clusterctl/cmd/describe_cluster.go:105 +0x2d
github.com/spf13/cobra.(*Command).execute(0x31aae60, {0xc00018af00, 0x8, 0x8})
        github.com/spf13/cobra@v1.7.0/command.go:940 +0x862
github.com/spf13/cobra.(*Command).ExecuteC(0x31ad980)
        github.com/spf13/cobra@v1.7.0/command.go:1068 +0x3bd
github.com/spf13/cobra.(*Command).Execute(...)
        github.com/spf13/cobra@v1.7.0/command.go:992
sigs.k8s.io/cluster-api/cmd/clusterctl/cmd.Execute()
        sigs.k8s.io/cluster-api/cmd/clusterctl/cmd/root.go:105 +0x25
main.main()
        sigs.k8s.io/cluster-api/cmd/clusterctl/main.go:27 +0x17
*/

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

[k8s-ci-robot]

Hi @bavarianbidi. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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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[killianmuldoon]

/ok-to-test

[killianmuldoon]

Second time I've seen this flake where the env cleanup fails 🤔

[ykakarap]

The nil check makes sense.

I will do another pass and will take a closer look at the updated tests.

[bavarianbidi]

The nil check makes sense.

I will do another pass and will take a closer look at the updated tests.

Thank you.

In the end, i just copied the FakeMachineDeployment generation to create another md where the bootstrap.configref is nil and a secret is used.
Wherever the origin FakeMachineDeployment was used in the test, i've added an additional test-case (or extended an existing one) to make use of the newly generated fake md as well.

[fabriziopandini]

thanks for this PR
/lgtm

@ykakarap @Jont828 for a final pass

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 31658f380bfe7f2f907d573d5b300afc2ed5e99e

[bavarianbidi]

@ykakarap / @Jont828 any chance to get this merged soon or do you want me to add something more?

[sbueringer]

Thank you very much. Very nice test coverage!!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: sbueringer

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