Support for CRD-specific watch namespaces configuration

[levan-m]

What does this PR do?

CECO-1021

For Reviewer: first commit is actual change; second commit is mostly refactor.

controller-runtime 0.16 allows cache configuration on resource level. This change adds CRD-specific watch namespace env vars and sets them on corresponding CRDs or related resources.

Motivation

What inspired you to submit this pull request?

Additional Notes

Anything else we should know when reviewing?

Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

Test using DatadogMonitors CRD, use following manifests to create monitors in two different namespaces.

• Namespace monitor1

  apiVersion: datadoghq.com/v1alpha1
  kind: DatadogMonitor
  metadata:
    name: datadog-monitor-test1
    namespace: monitor1
  spec:
    query: "avg(last_10m):avg:system.disk.in_use{*} by {host} > 0.5"
    type: "metric alert"
    name: "Test monitor made from DatadogMonitor monitor1"
    message: "We are running out of disk space!"
    tags:
      - "test:datadog"

• Namespace monitor2

  apiVersion: datadoghq.com/v1alpha1
  kind: DatadogMonitor
  metadata:
    name: datadog-monitor-test2
    namespace: monitor2
  spec:
    query: "avg(last_10m):avg:system.disk.in_use{*} by {host} > 0.5"
    type: "metric alert"
    name: "Test monitor made from DatadogMonitor monitor2"
    message: "We are running out of disk space!"
    tags:
      - "test:datadog"

Operator doesn't watch namespace1 or namespace2.

1. Run operator with datadogMonitorEnabled set to true (with API, APP key set), running in datadog namespace.
2. Set default watch namespaces env variable to current namespace

        - name: WATCH_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace

Operator shouldn't reconcile the monitors from other namespaces (nothing logged or created).

Add monitor1 namespace

1. In above setup add following env variable

      - name: DD_MONITOR_WATCH_NAMESPACE
        value: "monitor1"

Observe monitor from monitor1 namespace getting reconciled - check logs and datadog app to confirm it's created.

2. Add monitor2 to above env var

Observer monitor in monitor2 reconciled as well.

Write there any instructions and details you may have to test your PR.

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[github-actions]

This pull request does not contain a valid label. Please add one of the following labels: bug, enhancement, refactoring, documentation, tooling, dependencies

[github-actions]

This pull request does not contain a valid label. Please add one of the following labels: bug, enhancement, refactoring, documentation, tooling, dependencies

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 63.63636% with 40 lines in your changes missing coverage. Please review.

Project coverage is 55.03%. Comparing base (4bc766f) to head (10a4a65).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1235      +/-   ##
==========================================
+ Coverage   54.87%   55.03%   +0.16%     
==========================================
  Files         243      243              
  Lines       28120    28165      +45     
==========================================
+ Hits        15430    15502      +72     
+ Misses      11815    11785      -30     
- Partials      875      878       +3     

Flag	Coverage Δ
unittests	55.03% <63.63%> (+0.16%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
main.go	0.00% <0.00%> (ø)
pkg/config/config.go	67.92% <67.96%> (+67.92%)	⬆️

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4bc766f...10a4a65. Read the comment docs.

[brett0000FF]

I know you're still drafting this, but I left a couple very minor suggestions in the meantime. Please let Docs know if add more content and need another look!