kyverno/documentation/writing-policies-preconditions.md

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Preconditions

Preconditions allow controlling policy rule execution based on variable values.

While match & exclude conditions allow filtering requests based on resource and user information, preconditions can be used to define custom filters for more granular control.

The following operators are currently supported for preconditon evaluation:

• Equal
• Equals
• NotEqual
• NotEquals
• In
• NotIn

Example

  - name: generate-owner-role
    match:
      resources:
        kinds:
        - Namespace
    preconditions:
    - key: "{{serviceAccountName}}"
      operator: NotEqual
      value: ""

In the above example, the rule is only applied to requests from service accounts i.e. when the {{serviceAccountName}} is not empty.

  - name: generate-default-build-role
    match:
      resources:
        kinds:
        - Namespace
    preconditions:
    - key: "{{serviceAccountName}}"
      operator: In
      value: ["build-default", "build-base"]

In the above example, the rule is only applied to requests from service account with name build-default and build-base.

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