fix: Fill container statuses panic

[dbudziwojskiNR]

Description

Internal recreation of PR #1412

We have a pod restarting with panic logs:

panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
github.com/newrelic/nri-kubernetes/v3/src/kubelet/metric.fillContainerStatuses(0xc0000e6738, 0xc0000e6590)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/metric/pods.go:249 +0x103d
github.com/newrelic/nri-kubernetes/v3/src/kubelet/metric.(*PodsFetcher).fetchContainersData(0x13aa020?, 0xc0000e6738)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/metric/pods.go:181 +0xb7
github.com/newrelic/nri-kubernetes/v3/src/kubelet/metric.(*PodsFetcher).fillGaps(0xc0001369a0, 0xc0017e6660, {{{0xc001369558, 0x7}, {0xc001369570, 0x2}}, {{0x0, 0x0}, {0x0, 0x0}, ...}, ...})
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/metric/pods.go:102 +0x4e5
github.com/newrelic/nri-kubernetes/v3/src/kubelet/metric.(*PodsFetcher).DoPodsFetch(0xc0001369a0)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/metric/pods.go:78 +0x4ca
github.com/newrelic/nri-kubernetes/v3/src/kubelet/grouper.(*grouper).Group(0xc00015c320, 0xc001a819e0?)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/grouper/group.go:71 +0x1c7
github.com/newrelic/nri-kubernetes/v3/src/scrape.(*Job).Populate(0xc000565d00, 0xc000136580, {0xc00005207b, 0x6}, 0x1fb4040, 0xc00001c750)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/scrape/scrape_job.go:56 +0x5f
github.com/newrelic/nri-kubernetes/v3/src/kubelet.(*Scraper).Run(0xc00023b7c0, 0xc000136580)
/home/runner/work/nri-kubernetes/nri-kubernetes/src/kubelet/scraper.go:111 +0x44e
main.runScrapers(0xc00038ef08, 0x0?, 0xc00023b7c0, 0x0, 0xc000136580)
/home/runner/work/nri-kubernetes/nri-kubernetes/cmd/nri-kubernetes/main.go:228 +0xb6
main.main.func1()
/home/runner/work/nri-kubernetes/nri-kubernetes/cmd/nri-kubernetes/main.go:175 +0x39
main.measureTime(0xc001221ed0)
/home/runner/work/nri-kubernetes/nri-kubernetes/cmd/nri-kubernetes/main.go:215 +0x31
main.main()
/home/runner/work/nri-kubernetes/nri-kubernetes/cmd/nri-kubernetes/main.go:174 +0xf16

• The panic is caused by indexing pod.Status.InitContainerStatuses by idx when that slice can be shorter than pod.Spec.InitContainers.

• Put a for check to make sure the initContainerName is matching the status container name.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• New feature / enhancement (non-breaking change which adds functionality)
• Security fix
• Bug fix (non-breaking change which fixes an issue)

Checklist:

• Add changelog entry following the contributing guide
• Documentation has been updated
• This change requires changes in testing:
  • unit tests
  • E2E tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.89%. Comparing base (e19d9dd) to head (1ca47dc).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1488      +/-   ##
==========================================
+ Coverage   76.87%   76.89%   +0.01%     
==========================================
  Files          53       53              
  Lines        3784     3787       +3     
==========================================
+ Hits         2909     2912       +3     
  Misses        708      708              
  Partials      167      167              

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