Remove projected service account volume for workload identity

[JRBANCEL]

What type of PR is this?

/kind bug
/kind cleanup

What this PR does / why we need it:
See #4681.

Currently, in the manager spec, the projected volume for the service account token is manually specified.

The Workload Identity webhook takes care of this (and more) as seen here.

It is better to rely on the webhook because it is more future proof and removes YAML lines. Not only this, but as explained in #4681, not relying on the webhook makes it impossible to use cluster-api-provider-azure inside a vCluster on AKS with Workload Identity.

With this change, the resulting Pod spec in a vanilla case (i.e. not inside vCluster) is completely identical (webhook sets the volume), and it also works in vCluster because the Workload Identity webhook (on the host cluster) will do what is needed.

Which issue(s) this PR fixes:
Fixes #4681

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

NONE

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Hi @JRBANCEL. Thanks for your PR.

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[dtzar]

/ok-to-test

[nojnhuh]

Since we don't currently install the webhooks in our e2e tests, I'd expect the existing Workload Identity test to fail:

/test pull-cluster-api-provider-azure-e2e-optional

Introducing a requirement to install the webhooks would be a breaking change. Is there a way we could instead annotate the CAPZ pod so that the webhook ignores it? That kind of change I'd feel okay about backporting now and would at least buy us some time to solicit feedback on requiring the WorkloadIdentity webhooks and planning a transition if we find that's a better long-term solution.

[JRBANCEL]

Introducing a requirement to install the webhooks would be a breaking change.

Is using Workload Identity on AKS without the WI webhook even supported?
Official documentation requires to specify --enable-workload-identity which installs the WI webhook, no?

Is there a way we could instead annotate the CAPZ pod so that the webhook ignores it?

For #4681, no. Because we need the WI magic to be done on the host cluster (via webhook) and not at the source (inside vCluster).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.73%. Comparing base (d0f78e0) to head (51f03e4).
Report is 561 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4682      +/-   ##
==========================================
+ Coverage   62.71%   62.73%   +0.01%     
==========================================
  Files         192      192              
  Lines       15641    15641              
==========================================
+ Hits         9810     9812       +2     
+ Misses       5148     5146       -2     
  Partials      683      683              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[mjnovice]

@sonasingh46 do share your thoughts 🙏

[jackfrancis]

@JRBANCEL @mjnovice This change may work for vcluster scenarios, but it will break existing WI use cases in non-vcluster scenarios.

What are you doing right now to make this work? Are you manually updating the capz-controller-manager Deployment resource after you bootstrap your mgmt cluster on your vcluster?

[mjnovice]

@jackfrancis we are currently using kyverno to do tylhe patching on the host cluster.

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/lifecycle stale

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@JRBANCEL: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-api-provider-azure-e2e-optional	51f03e4	link	false	/test pull-cluster-api-provider-azure-e2e-optional
pull-cluster-api-provider-azure-e2e-aks	51f03e4	link	true	/test pull-cluster-api-provider-azure-e2e-aks
pull-cluster-api-provider-azure-ci-entrypoint	51f03e4	link	true	/test pull-cluster-api-provider-azure-ci-entrypoint

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/lifecycle rotten

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/close

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@k8s-triage-robot: Closed this PR.

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/close

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