Run

In the first getting started guide of wasmCloud you deployed a component using wadm via the wash app deploy command. Now, we're going to start the component "the long way" so that you can get a feel for all of the moving parts of the process. Our tooling documentation should help you get components started more easily, once you've been through this guide.

We assume you've already installed wash, the wasmCloud host, and necessary prerequisites.

Build the component

Building the component is as easy as running wash build in the project's root directory. The previous Build page has more details on the build process.

Start the component

info

If you don't have a host running, you can start one with wash up.

The simplest way to get a component running is by starting it from a locally built file. wasmCloud has support for starting built and signed components from absolute paths in addition to starting from OCI registries.

The wash build output will include the path to the locally built component. You can then use wash to start the component.

bash

# wash start component <path-to-component> <component-id>
wash start component file:///Users/wasmcloud/hello/build/http_hello_world_s.wasm hello

If you're running the wasmCloud dashboard with wash ui, you can take a look at your running component by visiting localhost:3000 in your browser. Alternatively, you can use wash to query the inventory of your running hosts:

bash

wash get inventory

console

➜ wash get inventory

  Host Inventory (NBPDHEE4FT75YJ7DLY2Y6W6WA2Z26ISRHSO5X3XBFBPAV53EI3GCPBHV)

  hostcore.os                        macos
  hostcore.arch                      aarch64
  hostcore.osfamily                  unix

  Component ID                       Name                      Image Reference
  hello                              http-hello-world          file:///Users/wasmcloud/hello/build/http_hello_world_s.wasm

Start the web server

We know our new component needs a web server, so let's start the HTTP server capability provider.

bash

wash start provider ghcr.io/wasmcloud/http-server:0.20.1 http-server

Add a link

bash

> wash inspect --wit ./build/http_hello_world_s.wasm

wit

package root:component;

world root {
  # ..imports

  export wasi:http/incoming-handler@0.2.0;
}

With both the provider and the component running, the next step is to link the two. Our component implements the function wasi:http/incoming-handler.handle, and the wasmCloud HTTP server provider is configured to call that function whenever it receives an HTTP request on the specified port.

First, create a named configuration for the HTTP server capability provider:

bash

wash config put hello-listen-address address=0.0.0.0:8085

Then, link the provider to the component and pass the configuration to the provider (the source of the link):

bash

# wash link put <source> <target> <namespace> <package> --source-config <config> --interface <interface>
wash link put http-server hello wasi http --source-config hello-listen-address --interface incoming-handler

At this point your HTTP server capability provider has been notified that a link definition was created, and it started the corresponding web server listening on port 8087. You can now hit that endpoint and exercise the code you just wrote:

bash

curl localhost:8085

and you should get the response:

console

Hello from Rust!

This page took you through the process of imperatively starting a component and a capability provider, and then linking them together. You can use these commands as you develop to work with running resources, or just use wash app to deploy the same resources declaratively.

Let's make a slight modification to the code, so you can see what it's like to go through a development iteration to compile and update the running code. Don't worry - this will be pretty quick.