Authorizer Plugins

A wasmcloud authorizer plugin is a Rust struct that implements the Authorizer trait. wasmcloud will always enforce that a given actor has the required capability attestation claims to invoke a capability provider. By default, wasmcloud allows actor-to-actor communications without restriction. If you wish to further limit the authorization scope used by wasmcloud, then you can supply your own authorizer which will be added to the security checks performed by the host runtime.

⚠️ NOTE - You can only ever further limit the scope of things granted access. Your authorizer plugin can never be used to reduce security by increasing the number of ways to obtain positive authorization.

The Authorizer trait (which is found in the wasmcloud-host crate), requires the following functions:

  • can_load(&Claims<Actor>) -> bool

Your plugin will be given the claims of the actor that is about to be loaded. If your function returns false, the actor module will not be loaded.

  • can_invoke(&Claims<Actor>, &WasmCloudEntity, &str) -> bool

This function will only be invoked if the core wasmcloud host has already determined that an invocation is authorized. Your function can then be used to decide to reject that assertion by returning false, or returning true to allow the invocation to go through.

In a release coming very soon, the authorizer plugins will have access to the claims of the target as well, allowing plugins to do things like perform allow-list checks against the issuer of the target, or require that both the source and the target of the invocation had the same issuer, etc.

⚠️ NOTE All first-party capability providers and example actors released by the wasmcloud team will be issued by the following account: