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Version: 1.0 (alpha)

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​

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.

Use wash build -o json to get the absolute path to the locally built component. You can then use wash to start the component.

bash
# Replace the path below with the path to your component
wash start component file:///Users/wasmcloud/hello/build/hello_s.wasm

If you're running the wasmCloud dashboard, 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

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 wasmcloud.azurecr.io/httpserver:0.19.1

With both the provider and the component running, the next step is to link the two. This provides a set of configuration values that is unique for each component's use of a provider. To link your component, you'll need the component's public key. You can get that by inspecting your local component file and making note of the Component key in the output (yours will be different from the output below).

bash
wash inspect ./build/hello_s.wasm
                              hello - Component
  Account       ACVKDPI2B3GFBAKURMYXBBDDTMJR3UQ7QLMAGE5Z6NNMTLAR276MZ2WF
  Component     MDLP5JLL7XMHGAYBUHGRBZHDVE4FIQLB6ONC2ZZG6HPNHPX6HZJ7EAJD
  Expires                                                          never
  Can Be Used                                                immediately
  Version                                                      0.1.0 (0)
  Call Alias                                                   (Not set)
                               Capabilities
  HTTP Server
                                   Tags
  None

Once you've got the component's public key, you can export a HELLO_COMPONENT_ID environment variable with that value and copy-and-paste the link command:

bash
# Paste your component ID after the `=` below (with no space after the `=`)
export HELLO_COMPONENT_ID=
bash
wash link put ${HELLO_COMPONENT_ID} VAG3QITQQ2ODAOWB5TTQSDJ53XK3SHBEIFNK4AYJ5RKAX2UNSCAPHA5M wasmcloud:httpserver address=0.0.0.0:8087

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:8087

and you should get the response:

Hello World

The component accepts an optional parameter name, and uses it to change the greeting. (Notice the quotes around the url below).

bash
curl "localhost:8087?name=Carol"

The response should be

Hello Carol

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.