DVO-105: extends the logic of matching "app" labels

[tremes]

DVO tries to group objects with the same app label value. Before this update, the operator tried to read the following paths to get the app label value:

• metadata.labels.app
• spec.selector.matchLabels.app

The problem with this approach is that labels can match using matchExpressions. An example is:

key: app
operator: NotIn
values:
- foo
- bar

which means match everything except of resources with app=foo or app=bar. This is a more effective approach but more complex.

The problem is that we don't know the set of app label values (in a namespace) in advance. So the logic here is to sort the found GroupVersionKinds according their group (this adds the apps/v1 group between the first in the slice) and then process the app label selectors.

[openshift-ci-robot]

@tremes: This pull request references DVO-105 which is a valid jira issue.

In response to this:

DVO tries to group objects with the same app label value. Before this update, the operator tried to read the following paths to get the app label value:

• metadata.labels.app
• spec.selector.matchLabels.app

The problem with this approach is that labels can match using matchExpressions. An example is:

key: app
operator: NotIn
values:
- foo
- bar

which means match everything except of resources with app=foo or app=bar. This is a more effective approach but more complex.

The problem is that we don't know the set of app label values (in a namespace) in advance. So the logic here is to sort the found GroupVersionKinds according their group (this adds the apps/v1 group between the first in the slice) and then process the app label selectors.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[codecov-commenter]

Codecov Report

Merging #252 (ce4ddbe) into master (2726809) will increase coverage by 2.31%.
The diff coverage is 77.21%.

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@@            Coverage Diff             @@
##           master     #252      +/-   ##
==========================================
+ Coverage   44.39%   46.70%   +2.31%     
==========================================
  Files          22       23       +1     
  Lines         910      972      +62     
==========================================
+ Hits          404      454      +50     
- Misses        472      479       +7     
- Partials       34       39       +5     

Impacted Files	Coverage Δ
pkg/utils/app_label.go	71.42% <71.42%> (ø)
pkg/controller/generic_reconciler.go	69.59% <91.30%> (+3.53%)	⬆️

[ncaak]

/lgtm

[openshift-ci]

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