bug: truncate volume names to 63 characters in BackupController executor

[SyeKlu]

Summary

This PR fixes volume name handling in the BackupController executor to comply with Kubernetes’ 63-character limit.
volumes[*].name is now automatically truncated to 63 characters, preventing errors caused by longer names.
Other related fields, such as persistentVolumeClaim.claimName and configMap.name, remain unaffected.

Related Issue:
Fixes k8up-io/k8up#862

[aw-talos]

Hello. I am also affected by this. Will it be fixed soon?

[arska]

Thanks for this contribution! We appreciate you taking the time to submit this PR.

To be able to merge it, we need the commits to be signed off (DCO — Developer Certificate of Origin), which is a requirement for all CNCF projects. You can do this by rebasing with:

git rebase --signoff HEAD~N

(where N is the number of commits in this PR)

and then force-pushing to your branch. If you have any questions about this, feel free to ask!

[SyeKlu]

The commit is now signed with DCO and ready.

[arska]

Thanks for the update and the sign-off!

The fix is correct but I'd suggest two improvements:

1. Extract a helper function instead of the inline anonymous function — it's more readable and testable:

// truncateVolumeName ensures the volume name doesn't exceed the Kubernetes 63-character limit.
func truncateVolumeName(name string) string {
	if len(name) > 63 {
		return name[:63]
	}
	return name
}

Then use it as:

Name: truncateVolumeName(pvc.Name),

2. Add a unit test to prevent regressions:

func TestTruncateVolumeName(t *testing.T) {
	tests := map[string]struct {
		input    string
		expected string
	}{
		"short name": {
			input:    "my-pvc",
			expected: "my-pvc",
		},
		"exactly 63 chars": {
			input:    strings.Repeat("a", 63),
			expected: strings.Repeat("a", 63),
		},
		"over 63 chars": {
			input:    strings.Repeat("a", 100),
			expected: strings.Repeat("a", 63),
		},
	}
	for name, tc := range tests {
		t.Run(name, func(t *testing.T) {
			assert.Equal(t, tc.expected, truncateVolumeName(tc.input))
		})
	}
}

Would you be able to make these changes? Happy to help if needed.

[SyeKlu]

I've adjusted it

[arska]

Looks great — clean helper function with good test coverage. Thank you for the update!

[arska]

CI is failing — missing strings import in the test file:

vet: operator/backupcontroller/backup_utils_test.go:93:14: undefined: strings

Please add "strings" to the imports in backup_utils_test.go and push.

[SyeKlu]

I’ve added the import.

[Kidswiss]

Hi @SyeKlu

Sorry for the late reply and thanks for the contribution!

There's a slight issue with possible collisions with your solution.

Given:
verylongpvcname-1
verylongpvcname-2

Let's assume the are both 65 chars long. So they would lose the appendix, resulting in the same string:

verylongpvcname

Which will also result in an error. So I'd suggest to first hash the whole name, shorten in to something lower than 64 (e.g. 58 or so), then add a - and the first 5 characters of the hash.

This will ensure that the truncation will not create a collision, well at least if there was no collision to begin with.