Exceptions

Exceptions let you specify cases where you allow policy violations. Trivy supports two types of exceptions.

Info

Exceptions can be applied to built-in policies as well as custom policies.

Namespace-based exceptions

There are some cases where you need to disable built-in policies partially or fully. Namespace-based exceptions lets you rough choose which individual packages to exempt.

To use namespace-based exceptions, create a Rego rule with the name exception that returns the package names to exempt. The exception rule must be defined under namespace.exceptions. data.namespaces includes all package names.

Example

package namespace.exceptions

import data.namespaces

exception[ns] {
    ns := data.namespaces[_]
    startswith(ns, "builtin.kubernetes")
}

This example exempts all built-in policies for Kubernetes.

Rule-based exceptions

There are some cases where you need more flexibility and granularity in defining which cases to exempt. Rule-based exceptions lets you granularly choose which individual rules to exempt, while also declaring under which conditions to exempt them.

To use rule-based exceptions, create a Rego rule with the name exception that returns the rule name suffixes to exempt, prefixed by deny_ (for example, returning foo will exempt deny_foo). The rule can make any other assertion, for example, on the input or data documents. This is useful to specify the exemption for a specific case.

Note that if you specify the empty string, the exception will match all rules named deny.

exception[rules] {
    # Logic

    rules = ["foo","bar"]
}

The above would provide an exception from deny_foo and deny_bar.

Example

package user.kubernetes.ID100

__rego_metadata := {
    "id": "ID100",
    "title": "Deployment not allowed",
    "severity": "HIGH",
    "type": "Kubernetes Custom Check",
}

deny_deployment[msg] {
    input.kind == "Deployment"
    msg = sprintf("Found deployment '%s' but deployments are not allowed", [name])
}

exception[rules] {
    input.kind == "Deployment"
    input.metadata.name == "allow-deployment"

    rules := ["deployment"]
}

If you want to apply rule-based exceptions to built-in policies, you have to define the exception under the same package.

Example

package builtin.kubernetes.KSV012

exception[rules] {
    input.metadata.name == "can-run-as-root"
    rules := [""]
}

This exception is applied to KSV012 in trivy-checks. You can get the package names in the trivy-checks repository or the JSON output from Trivy.