Struct Host 

pub struct Host { /* private fields */ }

A wasmcloud host that manages WebAssembly workloads and plugins.

The Host is the primary runtime for executing workloads. It manages:

• An engine for compiling and running WebAssembly components
• A collection of workloads and their states
• Plugins that extend host functionality
• System monitoring and resource tracking

Implementations

impl Host

pub fn builder() -> HostBuilder

Create a new builder for the host.

pub async fn start(self) -> Result<Arc<Self>>

Start the host and initialize all plugins.

This method must be called before the host can accept workloads. It starts all registered plugins and prepares the host for operation.

Returns

An Arc wrapped host ready to accept workloads.

Errors

Returns an error if any plugin fails to start.

pub async fn stop(self: Arc<Self>) -> Result<()>

Stop the host and shut down all plugins.

Attempts to gracefully stop all plugins with a 3-second timeout for each. Errors are logged but don’t prevent other plugins from being stopped.

Returns

Ok if the shutdown process completes (even with plugin errors).

pub fn label(&self, label: impl AsRef<str>) -> Option<&String>

Get a label value by key.

Arguments

• label - The label key to look up

Returns

The label value if it exists, None otherwise.

pub fn id(&self) -> &str

Get the unique identifier for this host.

Returns

The host’s unique ID string.

pub fn friendly_name(&self) -> &str

Get the human-readable name for this host.

Returns

The host’s friendly name string.

pub fn wit_world(&self) -> WitWorld

Returns the WIT (imports, exports) that this host can provide to any component.

Put another way, this represents a simplified version of the host world. For example, this WIT world:

package wasmcloud:host@0.1.0;

interface foo {
...
}
interface bar {
...
}

world host {
  import foo;
  export bar;
}

Would be returned as: ( vec![WitInterface { namespace: “wasmcloud”, package: “host”, interfaces: [“foo”], version: Some(“0.1.0”) }], vec![WitInterface { namespace: “wasmcloud”, package: “host”, interfaces: [“bar”], version: Some(“0.1.0”) }], )

This can be viewed as an inversion of the worlds that this host can support. In the above example, this host can support any component that imports bar and exports foo. Other exports will be ignored, and other imports that are unsatisfied will be rejected.

Trait Implementations

impl Debug for Host

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl HostApi for Host

async fn workload_start( &self, request: WorkloadStartRequest, ) -> Result<WorkloadStartResponse>

Start a workload

async fn heartbeat(&self) -> Result<HostHeartbeat>

Request a heartbeat containing the host’s current state and system information.

async fn workload_status( &self, request: WorkloadStatusRequest, ) -> Result<WorkloadStatusResponse>

Query the status of a running workload.

async fn workload_stop( &self, request: WorkloadStopRequest, ) -> Result<WorkloadStopResponse>

Stop a running workload on this host.