Taking Spin for a spin

Download the spin binary along with a starter set of templates and plugins using the install.sh script hosted on this site:

$ curl -fsSL https://developer.fermyon.com/downloads/install.sh | bash

Then move the spin binary somewhere in your path, so you can run it from anywhere. For example:

$ sudo mv ./spin /usr/local/bin/spin

Download the spin binary along with a starter set of templates and plugins using the install.sh script hosted on this site:

$ curl -fsSL https://developer.fermyon.com/downloads/install.sh | bash

Then move the spin binary somewhere in your path, so you can run it from anywhere. For example:

$ sudo mv ./spin /usr/local/bin/spin

Download the Windows binary release of Spin from GitHub.

Unzip the binary release and place the spin.exe in your system path.

$ spin templates install --git https://github.com/fermyon/spin --update
Copying remote template source
Installing template redis-rust...
Installing template http-rust...
... other templates omitted ...
+------------------------------------------------------------------------+
| Name                Description                                        |
+========================================================================+
| ... other templates omitted ...                                        |
| http-rust           HTTP request handler using Rust                    |
| redis-rust          Redis message handler using Rust                   |
| ... other templates omitted ...                                        |
+------------------------------------------------------------------------+

Note: The Rust templates are in a repo that contains several other languages; they will all be installed together.

$ spin templates install --git https://github.com/fermyon/spin-js-sdk --update
Copying remote template source
Installing template http-js...
Installing template http-ts...
+------------------------------------------------------------------------+
| Name                Description                                        |
+========================================================================+
| http-js             HTTP request handler using Javascript              |
| http-ts             HTTP request handler using Typescript              |
+------------------------------------------------------------------------+

$ spin templates install --git https://github.com/fermyon/spin-python-sdk --update
Copying remote template source
Installing template http-py...
+---------------------------------------------+
| Name      Description                       |
+=============================================+
| http-py   HTTP request handler using Python |
+---------------------------------------------+

$ spin templates install --git https://github.com/fermyon/spin --update
Copying remote template source
Installing template redis-go...
Installing template http-go...
+------------------------------------------------------------------------+
| Name                Description                                        |
+========================================================================+
| ... other templates omitted ...                                        |
| http-go             HTTP request handler using (Tiny)Go                |
| redis-go            Redis message handler using (Tiny)Go               |
| ... other templates omitted ...                                        |
+------------------------------------------------------------------------+

Note: The Go templates are in a repo that contains several other languages; they will all be installed together.

You’ll need the wasm32-wasi target for Rust:

$ rustup target add wasm32-wasi

Learn more in the language guide.

You’ll need the Spin js2wasm plugin:

$ spin plugins update
$ spin plugins install js2wasm --yes

Learn more in the language guide.

You’ll need the Spin py2wasm plugin:

$ spin plugins update
$ spin plugins install py2wasm --yes

Learn more in the language guide.

You’ll need the TinyGo compiler, as the standard Go compiler does not yet support the WASI standard. See the TinyGo installation guide.

Learn more in the language guide.

Use the spin new command and the http-rust template to scaffold a new Spin application:

$ spin new
Pick a template to start your application with:
  http-c (HTTP request handler using C and the Zig toolchain)
  http-csharp (HTTP request handler using C# (EXPERIMENTAL))
  http-go (HTTP request handler using (Tiny)Go)
  http-grain (HTTP request handler using Grain)
> http-rust (HTTP request handler using Rust)
  http-swift (HTTP request handler using SwiftWasm)
  http-zig (HTTP request handler using Zig)
  redis-go (Redis message handler using (Tiny)Go)
  redis-rust (Redis message handler using Rust)

Enter a name for your new application: hello_rust
Project description: My first Rust Spin application
HTTP base: /
HTTP path: /...

This command created a directory with the necessary files needed to build and run a Rust Spin application. Change to that directory, and look at the files. It looks very much like a normal Rust library project:

$ cd hello_rust
$ tree
.
├── .cargo
│   └── config.toml
├── .gitignore
├── Cargo.toml
├── spin.toml
└── src
    └── lib.rs

The additional spin.toml file is the manifest file, which tells Spin what events should trigger what components. In this case our trigger is HTTP, for a Web application, and we have only one component, at the route /.... This is a wildcard that matches any route:

spin_manifest_version = "1"
authors = ["Your Name <your-name@example.com>"]
description = "My first Rust Spin application"
name = "hello_rust"
trigger = { type = "http", base = "/" }
version = "0.1.0"

[[component]]
id = "hello-rust"
source = "target/wasm32-wasi/release/hello_rust.wasm"
allowed_http_hosts = []
[component.trigger]
route = "/..."
[component.build]
command = "cargo build --target wasm32-wasi --release"

This represents a simple Spin HTTP application (triggered by an HTTP request), with a single component called hello-rust. This component is on the route /..., which is a wildcard meaning it will match any route. When the application gets an HTTP request, Spin will map its route to the hello-rust component, and execute the associated hello_rust.wasm WebAssembly module.

Learn more about the manifest here.

Now let’s have a look at the code. Below is the complete source code for a Spin HTTP component written in Rust — a regular Rust function that takes an HTTP request as a parameter and returns an HTTP response, and it is annotated with the http_component macro which identifies it as the entry point for HTTP requests:

use anyhow::Result;
use spin_sdk::{
    http::{Request, Response},
    http_component,
};

/// A simple Spin HTTP component.
#[http_component]
fn handle_hello_rust(req: Request) -> Result<Response> {
    println!("{:?}", req.headers());
    Ok(http::Response::builder()
        .status(200)
        .header("foo", "bar")
        .body(Some("Hello, Fermyon".into()))?)
}

Use the spin new command and the http-ts template to scaffold a new Spin application. (If you prefer JavaScript to TypeScript, the http-js template is very similar.):

$ spin new
Pick a template to start your application with:
  http-js (HTTP request handler using Javascript)
> http-ts (HTTP request handler using Typescript)
Enter a name for your new application: hello_typescript
Project description: My first TypeScript Spin application
HTTP base: /
HTTP path: /...

This command created a directory with the necessary files needed to build and run a TypeScript Spin application. Change to that directory, and look at the files. It looks similar to a lot of NPM projects:

$ cd hello_typescript
$ tree
.
├── package.json
├── README.md
├── spin.toml
├── src
│   └── index.ts
├── tsconfig.json
└── webpack.config.js

The additional spin.toml file is the manifest file, which tells Spin what events should trigger what components. In this case our trigger is HTTP, for a Web application, and we have only one component, at the route /.... This is a wildcard that matches any route:

spin_manifest_version = "1"
authors = ["Your Name <your-name@example.com>"]
description = "My first TypeScript Spin application"
name = "hello_typescript"
trigger = { type = "http", base = "/" }
version = "0.1.0"

[[component]]
id = "hello-typescript"
source = "target/spin-http-js.wasm"
exclude_files = ["**/node_modules"]
[component.trigger]
route = "/..."
[component.build]
command = "npm run build"

This represents a simple Spin HTTP application (triggered by an HTTP request), with a single component called hello-typescript. This component is on the route /..., which is a wildcard meaning it will match any route. When the application gets an HTTP request, Spin will map its route to the hello-typescript component, and execute the associated spin-http-js.wasm WebAssembly module.

Learn more about the manifest here.

Now let’s have a look at the code. Below is the complete source code for a Spin HTTP component written in TypeScript — a regular function named handleRequest that takes an HTTP request as a parameter and returns an HTTP response. (The JavaScript version looks slightly different, but is still a function with the same signature.) The Spin js2wasm plugin looks for the handleRequest function by name when building your application into a Wasm module:

import { HandleRequest, HttpRequest, HttpResponse} from "@fermyon/spin-sdk"

const encoder = new TextEncoder()

export const handleRequest: HandleRequest = async function(request: HttpRequest): Promise<HttpResponse> {
    return {
      status: 200,
      headers: { "foo": "bar" },
      body: encoder.encode("Hello from TS-SDK").buffer
    }
}

Use the spin new command and the http-py template to scaffold a new Spin application.

$ spin new
Pick a template to start your application with:
> http-py (HTTP request handler using Python)
Enter a name for your new application: hello_python
Description: My first Python Spin application
HTTP base: /
HTTP path: /...

This command created a directory with the necessary files needed to build and run a Python Spin application. Change to that directory, and look at the files. It contains a minimal Python application:

$ cd hello_python
$ tree
.
├── app.py
├── Pipfile
├── README.md
└── spin.toml

The additional spin.toml file is the manifest file, which tells Spin what events should trigger what components. In this case our trigger is HTTP, for a Web application, and we have only one component, at the route /.... This is a wildcard that matches any route.

spin_manifest_version = "1"
authors = ["Your Name <your-name@example.com>"]
description = "My first Python Spin application"
name = "hello_python"
trigger = { type = "http", base = "/" }
version = "0.1.0"

[[component]]
id = "hello-python"
source = "app.wasm"
[component.trigger]
route = "/..."
[component.build]
command = "spin py2wasm app -o app.wasm"

This represents a simple Spin HTTP application (triggered by an HTTP request), with a single component called hello-python. This component is on the route /..., which is a wildcard meaning it will match any route. When the application gets an HTTP request, Spin will map its route to the hello-python component, and execute the associated app.wasm WebAssembly module.

Learn more about the manifest here.

Now let’s have a look at the code. Below is the complete source code for a Spin HTTP component written in Python — a regular function named handle_request that takes an HTTP request as a parameter and returns an HTTP response. The Spin py2wasm plugin looks for the handle_request function by name when building your application into a Wasm module.

from spin_http import Response

def handle_request(request):
    return Response(200,
                    [("content-type", "text/plain")],
                    bytes(f"Hello from the Python SDK", "utf-8"))

Use the spin new command and the http-go template to scaffold a new Spin application.

$ spin new
Pick a template to start your application with:
  http-c (HTTP request handler using C and the Zig toolchain)
  http-empty (HTTP application with no components)
> http-go (HTTP request handler using (Tiny)Go)
  http-grain (HTTP request handler using Grain)
  http-php (HTTP request handler using PHP)
  http-rust (HTTP request handler using Rust)
Enter a name for your new application: hello_go
Description: My first Go Spin application
HTTP base: /
HTTP path: /...

This command created a directory with the necessary files needed to build and run a Go Spin application using the TinyGo compiler. Change to that directory, and look at the files. It looks very much like a normal Go project:

$ cd hello_go
$ tree
.
├── go.mod
├── go.sum
├── main.go
└── spin.toml

The additional spin.toml file is the manifest file, which tells Spin what events should trigger what components. In this case our trigger is HTTP, for a Web application, and we have only one component, at the route /.... This is a wildcard that matches any route.

spin_manifest_version = "1"
authors = ["Your Name <your-name@example.com>"]
description = "My first Go Spin application"
name = "hello_go"
trigger = { type = "http", base = "/" }
version = "0.1.0"

[[component]]
id = "hello-go"
source = "main.wasm"
allowed_http_hosts = []
[component.trigger]
route = "/..."
[component.build]
command = "tinygo build -target=wasi -gc=leaking -no-debug -o main.wasm main.go"

This represents a simple Spin HTTP application (triggered by an HTTP request), with a single component called hello-go. This component is on the route /..., which is a wildcard meaning it will match any route. When the application gets an HTTP request, Spin will map its route to the hello-go component, and execute the associated main.wasm WebAssembly module.

Learn more about the manifest here.

Now let’s have a look at the code. Below is the complete source code for a Spin HTTP component written in Go. Notice where the work is done. The main function is empty (and Spin never calls it). Instead, the init function sets up a callback, and passes that callback to spinhttp.Handle to register it as the handler for HTTP requests. You can learn more about this structure in the Go language guide.

package main

import (
        "fmt"
        "net/http"

        spinhttp "github.com/fermyon/spin/sdk/go/http"
)

func init() {
        spinhttp.Handle(func(w http.ResponseWriter, r *http.Request) {
                w.Header().Set("Content-Type", "text/plain")
                fmt.Fprintln(w, "Hello Fermyon!")
        })
}

func main() {}

$ spin build
Executing the build command for component hello-rust: cargo build --target wasm32-wasi --release
    Updating crates.io index
    Updating git repository `https://github.com/fermyon/spin`
    Updating git repository `https://github.com/bytecodealliance/wit-bindgen`
   Compiling anyhow v1.0.69
   Compiling version_check v0.9.4
   # ...
   Compiling spin-sdk v0.10.0 
   Compiling hello-rust v0.1.0 (/home/ivan/testing/start/hello_rust)
    Finished release [optimized] target(s) in 11.94s
Successfully ran the build command for the Spin components.

If the build fails, check:

• Are you in the hello_rust directory?
• Did you successfully install the wasm32-wasi target?
• Is your version of Rust up to date (cargo --version)? The Spin SDK needs Rust 1.64 or above.

If you would like to know what build command Spin runs for a component, you can find it in the manifest, in the component.build section:

[component.build]
command = "cargo build --target wasm32-wasi --release"

You can always run this command manually; spin build is a shortcut to save you having to remember it.

As normal for NPM projects, before you build for the first time, you must run npm install:

$ npm install

added 134 packages, and audited 135 packages in 2s

18 packages are looking for funding
  run `npm fund` for details

found 0 vulnerabilities

Then run spin build:

$ spin build
Executing the build command for component hello-typescript: npm run build

> hello-typescript@1.0.0 build
> npx webpack --mode=production && mkdir -p target && spin js2wasm -o target/spin-http-js.wasm dist/spin.js

asset spin.js 4.57 KiB [emitted] (name: main)
runtime modules 670 bytes 3 modules
./src/index.ts 2.85 KiB [built] [code generated]
webpack 5.75.0 compiled successfully in 1026 ms

Starting to build Spin compatible module
Preinitiating using Wizer
Optimizing wasm binary using wasm-opt
Spin compatible module built successfully
Successfully ran the build command for the Spin components.

If the build fails, check:

• Are you in the hello_typescript directory?
• Did you run npm install before building`?
• Did you install the js2wasm plugin?

If you would like to know what build command Spin runs for a component, you can find it in the manifest, in the component.build section:

[component.build]
command = "npm run build"

You can always run this command manually; spin build is a shortcut.

$ spin build
Executing the build command for component hello-python: spin py2wasm app -o app.wasm
Spin-compatible module built successfully
Successfully ran the build command for the Spin components.

If the build fails, check:

• Are you in the hello_python directory?
• Did you install the py2wasm plugin?

If you would like to know what build command Spin runs for a component, you can find it in the manifest, in the component.build section:

[component.build]
command = "spin py2wasm app -o app.wasm"

You can always run this command manually; spin build is a shortcut.

$ spin build
Executing the build command for component hello-go: tinygo build -target=wasi -gc=leaking -no-debug -o main.wasm main.go
go: downloading github.com/fermyon/spin/sdk/go v0.10.0
Successfully ran the build command for the Spin components.

If the build fails, check:

• Are you in the hello_go directory?
• Did you successfully install TinyGo?
• Are your versions of Go and TinyGo up to date? The Spin SDK needs TinyGo 0.27 or above.
• Set Environment Variable CGO_ENABLED=1. (Since the Go SDK is built using CGO, it requires the CGO_ENABLED=1 environment variable to be set.)

If you would like to know what build command Spin runs for a component, you can find it in the manifest, in the component.build section:

[component.build]
command = "tinygo build -target=wasi -gc=leaking -no-debug -o main.wasm main.go"

You can always run this command manually; spin build is a shortcut to save you having to remember it.