Lattice Controller Capability Provider

A capability provider that allows components to interact with the lattice control interface (wasmcloud:latticecontrol) by remotely communicating with lattices and the hosts contained within them via NATS.

Configuration

This capability provider is designed to facilitate connections to multiple lattices. For each connection that components need to utilize, there must be an accompanying set_lattice_credentials call, even if you are establishing a connection to the default lattice.

It may not be immediately obvious, but because of the flexible design of wasmCloud's lattice, the component(s) that set credentials need not be the same component(s) that utilize the established connections so long as they are all bound to the provider via empty link definitions.

Further, you can run multiple instances of this provider in a source lattice (e.g. not necessarily one you're remotely managing) and it will automatically scale, with each instance maintaining its own cached connection to the appropriate lattices.

⚠️ Compatibility Warning for versions < 0.9.0 ⚠️

In previous versions of this capability provider, the provider would only ever establish one lattice control connection per instance, typically associated with the link name. The configuration for the lattice connection would come from the data on the link definition.

This is not how the current version of the provider works. The current provider is a multiplexed provider supporting multiple lattices. A component needs to establish a link once via an empty link definition, and then establish connections to remote lattices by using the set_lattice_credentials operation on the provider.

This provider no longer supports fallback connections supplied via the provider configuration parameter at startup. In other words, you must invoke set_lattice_credentials at least once to use this provider.

Component Usage Example

The following is an example of what it looks like for a component to utilize this capability provider. In this sample, the component is requesting that the echo component (10 instances of it) be started in the default lattice:

async fn start_component(ctx: &Context) -> RpcResult<CtlOperationAck> {
    let lattice = LatticeControllerSender::new();
    // Instruct provider to use anonymous local for NATS client for `default` lattice
    let _ = lattice.set_lattice_credentials(SetLatticeCredentialsRequest {
        lattice_id: "default".to_string(),
        nats_url: None,
        user_jwt: None,
        user_seed: None
    }).await;

    let cmd = StartComponentCommand {
        lattice_id: "default".to_string(),
        actor_ref: "wasmcloud.azurecr.io/echo:0.3.4".to_string(),
        annotations: None,
        count: 10,
        host_id: "NB67YNOVU5YB3526RUNCKNZBCQDH2L5NZJKQ6FWOVWGSHNHHEO65RP4A".to_string(),
    };

    debug!("Starting 10 instances of the echo component...");

    lattice.start_actor(ctx, &cmd).await
}