1. Home
2. Learn to build on the Fastly platform

Compute@Edge services

Compute@Edge is a computation platform capable of running custom binaries that you compile on your own systems and upload to Fastly. Security and portability is provided by compiling your code to WebAssembly.

Getting started

Create a Fastly account

To use Compute@Edge, you must create a Fastly account if you don't already have one.

Generate an API token

Compute@Edge services use packages built on your computer using the Fastly CLI. To authenticate the Fastly CLI, you must create an API token for your account. Follow the steps for creating an API token, make sure it has global scope, and make a note of the token.

Download and install the Fastly CLI

The Fastly CLI is available for multiple operating systems.

• MacOS: Install from Homebrew:

  $ brew install fastly/tap/fastly

• Windows: Visit the GitHub repo to download the prebuilt binary for your architecture.
• Linux: Packages are available for many distributions, along with prebuilt binaries. Visit the GitHub repo to download the package for your distro.

Verify everything works by running fastly version. For example:

$ fastly version
Fastly CLI version vX.Y.Z (abc0001)
Built with go version go1.18 linux/amd64
Viceroy version: viceroy X.Y.Z

The CLI will notify you if a new version is available. You can update it using the fastly update command.

Configure the Fastly CLI

The CLI interacts with Fastly via our API, authenticated using an API token. Configure the CLI to act on your behalf using the token you previously created, using one of the following options:

• (Recommended) Run fastly profile create and follow the interactive prompts. This will store your API token credential in a configuration file and remember it for subsequent commands.
• Include the token explicitly on each command you run using the --token or -t flags.
• Set a FASTLY_API_TOKEN environment variable.

For an overview of all available commands, run fastly with no arguments. Summarized help about any command or subcommand is available via the --help flag (e.g., fastly service --help). For verbose help, use the help command (e.g., fastly help service).

Choose a language to use

Fastly supports client SDKs for several languages that can compile to Compute@Edge compatible Wasm packages. Choose a language below to view language-specific guidelines for our most popular SDKs.

SDK version	0.9.1	1.3.1	0.1.1
Core features
Geolocation	✅	✅	✅
Dynamic compression ℹ️	✅	✅	✅
Auto decompression ℹ️	✅	-	✅
Environment variables ℹ️	✅	✅	✅
Cache override ℹ️	✅	✅	✅
Real time logging ℹ️	✅	✅	✅
Edge dictionaries ℹ️	✅ see note 1	✅	✅
Fanout ℹ️	✅	-	-
Websockets passthrough ℹ️	✅	-	-
Pre-release features
Object stores	✅	✅	-
Config stores	✅	✅	-
Secret stores	✅	-	-
Dynamic backends	✅	✅	-
Purging see note 2	✅	-	-
Backend health	✅	-	-
	Use Rust »	Use JavaScript »	Use Go »

We recommend the use of official Fastly SDKs (available for Rust, JavaScript, Go and AssemblyScript), but you can also create your own for a language of your choice, or use a community-created SDK. Learn more about custom SDKs.

Install local dependencies

To build your project, the Fastly CLI requires your local toolchain to be available and up to date. To install the toolchain for your chosen language, follow these instructions:

$ curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable

$ rustup target add wasm32-wasi --toolchain stable

$ rustup toolchain add stable

$ rustup target add wasm32-wasi --toolchain stable

Create a new Compute@Edge project

Use fastly compute init to scaffold a new Fastly Compute@Edge project. The CLI will generate source code for your project in the current working directory.

To get you started, we have made a library of Compute@Edge starter kit applications that are ready to compile and run on your service, so you can start from a working example that is as close as possible to the solution you are trying to achieve.

Right now, we offer the following starter kits:

• Authenticate at edge with OAuth
• Default starter for AssemblyScript
• Default starter for Go
• Default starter for JavaScript
• Empty starter for JavaScript
• Default starter kit for Expressly
• OpenAPI Validation (JS)
• Queuing / Waiting room (JS)
• Beacon termination
• Connect to Google Bigquery for Rust
• Default starter for Rust
• Empty starter for Rust
• Fanout starter for Rust
• Fanout forwarding starter for Rust
• Static content
• WebSockets starter for Rust
• Fastly Compute@Edge Starter kit for Fauna
• Optimizely Full Stack
• Integrate Storj using Rust

When you initialize a Compute@Edge project with fastly compute init, you'll be prompted to choose one of these starter kits.

$ mkdir example && cd example
$ fastly compute init

The system will display a series of prompts to guide you through the process of setting up your new project.

Creating a new Compute@Edge project.

Press ^C at any time to quit.

Name: [example]
Description: hello world rust project
Author: Service Author
Language:
[1] Rust (limited availability)
[2] JavaScript (limited availability)
[3] Go (beta)
[4] AssemblyScript (beta)
[5] Other ('bring your own' Wasm binary)
Choose option: [1]
Starter kit:
[1] Default starter for Rust
    A basic starter kit that demonstrates routing, simple synthetic responses and
    overriding caching rules.
    https://github.com/fastly/compute-starter-kit-rust-default
[2] Beacon termination
    Capture beacon data from the browser, divert beacon request payloads to a log
    endpoint, and avoid putting load on your own infrastructure.
    https://github.com/fastly/compute-starter-kit-rust-beacon-termination
[3] Static content
    Apply performance, security and usability upgrades to static bucket services such as
    Google Cloud Storage or AWS S3.
    https://github.com/fastly/compute-starter-kit-rust-static-content
Choose option or paste git URL: [1]

At the prompts, provide details about the service you're creating:

• Name: Enter a name for your service. By default, the CLI will use the name of the current directory.
• Description: Enter a short description for your service, or leave it blank.
• Author: Enter an email address as the author of the service package if desired.
• Language: Select the toolchain you wish to use to build your service.
• Starter kit: Choose from the available starter kits or press enter to accept the default. You may also enter the URL of a GitHub repo to use a template not in the list.

The CLI will set up a local development environment and a fastly.toml package manifest based on your selections, and provide some useful links and commands for working with your project:

✓ Initializing...
✓ Fetching package template...
✓ Updating package manifest...
✓ Initializing package...

Initialized package example to:
        /home/me/example

To publish the package (build and deploy), run:
        fastly compute publish

To learn about deploying Compute@Edge projects using third-party orchestration tools, visit:
        https://developer.fastly.com/learning/integrations/orchestration/


SUCCESS: Initialized package example

By default fastly compute init will create your project in the current directory. To specify a different one, use the --directory flag, but remember to change to the target directory before executing any other commands that you want to run in the context of the new project.

Compile the project to a Wasm binary

To run the Compute@Edge project on Fastly, it needs to be compiled into a WebAssembly module that can be packaged for Fastly use. The CLI internally runs the appropriate compiler for the language you're using, and generates the necessary WebAssembly binary.

$ fastly compute build

A successful build looks like this:

$ fastly compute build
✓ Initializing...
✓ Verifying package manifest...
✓ Verifying local <selected language> toolchain...
✓ Building package using <selected language> toolchain...
✓ Creating package archive...

SUCCESS: Built <selected language> package <name> (pkg/<name>.tar.gz)

Deploy the project to a new Fastly service

To deploy the project to Fastly, run fastly compute deploy.

If you already have a Fastly service you want to deploy the package to, you can add the service ID into the service_id property in fastly.toml before running the deploy command, but if not, we'll create a service for you automatically.

At the prompts, provide details about the service you're creating:

• Domain: Press enter to accept the automatically generated domain name (we'll take care of the TLS and DNS and give you a working domain immediately) or enter the name of the domain you'd like to associate with your service. You can also accept the default now and add more domains to the service later if you prefer.
• Backend: If you want to configure an origin server for your service, enter a valid hostname, or an IPv4 or IPv6 address. Alternatively leave the prompt blank to create a service with no origin server. Such services cannot forward requests to your servers, but they can respond to client requests with a response composed within your Compute@Edge package.

$ fastly compute deploy

There is no Fastly service associated with this package. To connect to an existing service
add the Service ID to the fastly.toml file, otherwise follow the prompts to create a
service now.

Press ^C at any time to quit.

Create new service: [y/N] y

✓ Initializing...
✓ Creating service...

Domain: [random-funky-words.edgecompute.app]

Backend (hostname or IP address, or leave blank to stop adding backends):

✓ Initializing...
✓ Creating domain 'random-funky-words.edgecompute.app'...
✓ Uploading package...
✓ Activating version...

Manage this service at:
        https://manage.fastly.com/configure/services/PS1Z4isxPaoZGVKVdv0eY

View this service at:
        https://random-funky-words.edgecompute.app


SUCCESS: Deployed package (service PS1Z4isxPaoZGVKVdv0eY, version 1)

The output includes a link to manage your service in the Fastly web interface. You can use this link to perform more complex configuration of the service, such as adding or removing domains, changing origin server settings, and setting up logging endpoints.

After the command completes, it may take up to an additional 20 seconds before the package begins handling requests, and if you're replacing a previous version of the package, the earlier version may continue to handle requests for up to a minute.

Test and celebrate

Open a browser or use a command line HTTP client such as cURL to issue a request to the domain that you assigned to the service.

$ curl -si "https://random-funky-words.edgecompute.app/"
HTTP/2 200
content-type: text/html; charset=utf-8
date: Tue, 09 Nov 2021 17:25:05 GMT
content-length: 666

<!DOCTYPE html>
<html lang="en">
...
</html>

Or if you prefer, test it in a web browser:

Next steps

Now that you have a working project deployed, you have the basic building blocks in place to be successful with Compute@Edge.

If you would like to learn more about how Compute@Edge integrates with your preferred language, read our getting started guides for Rust, JavaScript, Go or AssemblyScript.

If you are already familiar with VCL and want to migrate an existing VCL configuration to Compute@Edge, try the VCL to Compute@Edge migration guide, which shows examples of the most common use cases in VCL and how to implement the same functionality using Compute@Edge's supported languages.

Or maybe you have an idea in mind and you want to experiment with examples? Try cloning a starter kit, copy and pasting code from some examples, or following a tutorial.

Limitations and constraints

Compute@Edge services allow connections to backends on ports 80 and 443, and accept client connections on port 443 only. This is different from VCL services, which support client connections on port 80.

The following default limits apply to Compute@Edge services. If you need to exceed one of these limits, please speak to your Fastly contact or reach out to support@fastly.com:

An 'execution' refers to a single instance of Compute@Edge being executed, normally in response to a client HTTP request. Separate limits also apply to the use of log tailing with Compute@Edge services.