Fix emptyDir sizeLimit handling in our CRDs

[scholzj]

Type of change

• Bugfix

Description

#12067 describes a pretty nasty bug in our CRDs. The additional volumes in the Pod template use the native Fabric8 EmptyDirVolumeSource class in the API model. However, this class relies on the Fabric8 Quantity class and this class has a structure that our CRDs cannot handle. As a result:

• The CRDs have a wrong structure for configuring the size limit of the emptyDir volumes, which does not allow using the right Kubernetes format:

            emptyDir:
              sizeLimit: 10Mi
              medium: Memory

  and instead expects something like this:

            emptyDir:
              sizeLimit:
                amount: 10
                format: Gi
              medium: Memory

• However, even with the wrong format generated into the CRDs, Strimzi cannot decode the it and it cannot be used.

This PR creates our own model class to replace the Fabric8 EmptyDirVolumeSource. It does not use Quantity (similarly to our storage configuration) and makes sure the CRDs use the correct layout and Strimzi can handle it.

However, strictly speaking, this breaks the compatibility of the API. Given that it:

• Introduces the correct layout intended from the beginning
• This does not work in the existing CRDs / layout anyway
• This is the first complaint about it, so nobody seems ti be using it

I think it might be ok to do this. But there is some extent of risk worth considering during the review.

This should resolve #12067

Checklist

• Write tests
• Make sure all tests pass
• Update documentation
• Try your changes from Pod inside your Kubernetes and OpenShift cluster, not just locally
• Reference relevant issue(s) and close them after merging

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.79%. Comparing base (1ee54de) to head (963b3c0).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #12068      +/-   ##
============================================
+ Coverage     74.78%   74.79%   +0.01%     
- Complexity     6614     6618       +4     
============================================
  Files           376      376              
  Lines         25325    25329       +4     
  Branches       3389     3391       +2     
============================================
+ Hits          18939    18945       +6     
  Misses         4998     4998              
+ Partials       1388     1386       -2     

Files with missing lines	Coverage Δ
.../strimzi/operator/cluster/model/TemplateUtils.java	94.00% <100.00%> (+0.52%)	⬆️

... and 1 file with indirect coverage changes

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[scholzj]

/gha run pipeline=regression

[github-actions]

⏳ System test verification started: link

The following 6 job(s) will be executed:

• regression-brokers-and-security-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operators-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-operands-amd64 (oracle-vm-8cpu-32gb-x86-64)
• regression-brokers-and-security-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operators-arm64 (oracle-vm-8cpu-32gb-arm64)
• regression-operands-arm64 (oracle-vm-8cpu-32gb-arm64)

Tests will start after successful build completion.

[github-actions]

🎉 System test verification passed: link