--- title: OPA overview: Adapter that implements an Open Policy Agent engine location: https://istio.io/docs/reference/config/adapters/opa.html layout: protoc-gen-docs number_of_entries: 1 ---

The `opa` adapter exposes an Open Policy Agent engine that provides sophisticated access control mechanisms.

## Params

Configuration format for the `opa` adapter.

Example configuration:

    policy:
      - |+
        package mixerauthz
        policy = [
          {
            "rule": {
              "verbs": [
                "storage.buckets.get"
              ],
              "users": [
                "bucket-admins"
              ]
            }
          }
        ]

        default allow = false

        allow = true {
          rule = policy[_].rule
          input.subject.user = rule.users[_]
          input.action.method = rule.verbs[_]
        }
    checkMethod: "data.mixerauthz.allow"
    failClose: true

Field | Type | Description
--- | --- | ---
`policy` | `string[]` | List of OPA policies
`checkMethod` | `string` | Query method to check. Format: data..
`failClose` | `bool` | Close the client request when adapter has a issue. If failClose is set to true and there is a runtime error, instead of disabling the adapter, close the client request