Auto-recover policy report

[realshuting]

Signed-off-by: Shuting Zhao shutting06@gmail.com

Related issue

/kind bug
/kind feature

fixes #1577
fixes #1277
fixes #1682

This PR:

• allows users to configure background scan interval by flag --background-scan, the default is set to one hour. The allowed format can be 30s, 15m, 12h.
• reconciles policy reports at the given interval (background scan interval), refreshes the policy results entries, and removes invalid records
• re-creates policy report if it gets deleted
• reconciles policy reports if resourceFilters (configured in the Configmap) changes

What type of PR is this

Proposed changes

Checklist

• I have read the contributing guidelines.
• [] I have added tests that prove my fix is effective or that my feature works.
• I have added or changed the documentation.
  • If not, I have raised an issue in kyverno/website to track the doc update: Add doc - configure background interval website#120

Further comments

Ideally we want to refresh Cluster/policy cache to trigger the reconciliation of the policy controller, but there's a check to not re-queue the policy if the spec does not change. So this PR adds a ticker to trigger the reconciliation.