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Your First Module

Creating and Running a Waxosuit WebAssembly Module

In this tutorial, you’ll be creating your first WebAssembly module for use with Waxosuit. This will consist of three main steps:

  • Create and build the WebAssembly Module
  • Sign the module
  • Run the module in Waxosuit

What You’ll Need to Start

You’ll need to have a few things ready before you can do this tutorial:

  • waxosuit - Eventually you’ll want this installed, but for now you can just use the docker image.
  • wascap - you will need the wascap tool installed (cargo install wascap --features "cli"). This is used to sign and verify WebAssembly modules.
  • cargo generate - you will need the cargo-generate crate installed (cargo install cargo-generate) to create a project from the waxosuit-guest-template
  • wasm32-unknown-unknown target - You’ll need to make sure that you can compile to the wasm32 target. To do this, run rustup target add wasm32-unknown-unknown

Create and Build a Module

To create a new Waxosuit module project in Rust, you can use cargo generate to produce a new project from our project template as shown in the following example:

$ cargo generate --git
Project Name: HelloWorld
Renaming project called `HelloWorld` to `hello-world`...
Creating project called `hello-world`...
Done! New project created /home/kevin/demo/hello-world

In this example we chose HelloWorld as the project name, but you can choose anything you like. As soon as this new project is generated, you can go to that project’s directory and compile it (already configured to build to the wasm32-unknown-unknown target):

$ cd hello-world
$ make build
 Compiling hello-world v0.1.0 (/home/kevin/demo/hello-world)
    Finished dev [unoptimized + debuginfo] target(s) in 41.23s

This new module comes with a default call handler (covered in the next tutorial in the series) that will answer all incoming HTTP requests with a 200/OK, and it also answers health requests and identity requests by default. You’ll see that when we go to run it with the waxosuit binary soon.

$ ls target/wasm32-unknown-unknown/debug/*.wasm

Sign a Module

In future tutorials and the documentation you’ll see how to sign WebAssembly modules. For now, this step is taken care of for you because the new project template comes with a .keys directory, containing some development keys. All you need is wascap in your path for the Makefile to work.

Both the build and release tasks in the Makefile will automatically sign your module.

Run Your Module in Waxosuit

It’s time to run our module!

To do this, we’re going to create a docker image from the waxosuit/waxosuit image and will combine that with the signed WebAssembly module produced during the build process. To create the docker image, just issue the following command:

$ make docker

You’ll see the release build get compiled and then you’ll see the wasm file get added to the docker image.

Now you can just use docker to run your WebAssembly module: (you’ll need to use docker kill to terminate the process when you’re done)

$ docker run -e RUST_LOG="info,cranelift_wasm=warn" -p 8080:8080 hello-world
[2019-06-28T05:46:42Z INFO  waxosuit_host::capabilities] Loaded capability: wascap:http_server, provider: Actix-Web HTTP Server
[2019-06-28T05:46:42Z INFO  wascap_httpsrv] Dispatcher received.
[2019-06-28T05:46:42Z INFO  waxosuit] Capability provider wascap:http_server loaded
[2019-06-28T05:46:42Z INFO  actix_server::builder] Starting 4 workers
[2019-06-28T05:46:42Z INFO  actix_server::builder] Starting server on
[2019-06-28T05:46:42Z INFO  waxosuit_host::capabilities] Loaded capability: wascap:messaging, provider: NATS Messaging Provider
[2019-06-28T05:46:42Z INFO  waxosuit_host::capabilities] Capability provider for wascap:messaging not claimed by guest module. Unloading.
[2019-06-28T05:46:42Z INFO  waxosuit] Capability provider not loaded: WASCAP contract violation: Unauthorized capability: wascap:messaging
[2019-06-28T05:46:42Z INFO  waxosuit_host::capabilities] Loaded capability: wascap:keyvalue, provider: Redis Key-Value Provider
[2019-06-28T05:46:42Z INFO  waxosuit_host::capabilities] Capability provider for wascap:keyvalue not claimed by guest module. Unloading.
[2019-06-28T05:46:42Z INFO  waxosuit] Capability provider not loaded: WASCAP contract violation: Unauthorized capability: wascap:keyvalue
[2019-06-28T05:46:42Z INFO  waxosuit] Starting Waxosuit for module hello with capability claims - wascap:http_server

We set the RUST_LOG environment variable so we don’t see the spam from the Cranelift compiler as it JITs the WebAssembly instructions and so we can see useful information coming from the WebAssembly module, Waxosuit, and its capability providers. You can see in the preceding output that the Messaging (NATS) and Key-Value (Redis) provider plug-ins both get unloaded because the signed Wasm module doesn’t have those capability grants.

Now that Waxosuit is hosting your Wasm file, open another terminal window and you can curl the identity endpoint that the Waxosuit HTTP server provides automatically:

$ curl localhost:8080/id | jq
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   231  100   231    0     0  57750      0 --:--:-- --:--:-- --:--:-- 77000
  "capabilities": [

Note that the values for module and issuer in the above JSON will be the public keys of the account and module that came with the new project template.

To test that your WebAssembly module is functioning the way it should, issue any HTTP request on the 8080 port and it should return a HTTP 200 status code.

Congratulations ! You’ve compiled, signed, and executed a WebAssembly module designed to run in the cloud. In the next tutorial, you’ll start using the capabilities available to your module.