Fastly Compute@Edge Quickstart for Swift

This is an example Fastly Compute@Edge app using Andrew Barba’s Swift Compute Runtime SDK.

It’s designed to demonistrate some simple functionality:

  1. Routing
  2. Accessing request object (method, url, headers)
  3. Writing repsponse (JSON and text)
  4. Setting response status (200 vs. 404)

See the SDK Reference for more info.


The following is the code for this demo.

import Compute

struct Response: Codable {
    let version: Int
    let message: String

struct ComputeApp {
    static func main() async throws {
        try await onIncomingRequest { req, res in
            let logger = try Logger(name: "QuickstartLog")
            switch (req.method, req.url.path) {
            case (.post, "/quickstart"):
                if let accept = req.headers.get("Accept") {
                    if accept.caseInsensitiveCompare("text/plain") == .orderedSame {
                        try logger.write("swift quickstart responded with 200")
                        try await res.status(200).send("Hello, Swift World!")
                let content = Response(version: 1, message: "Hello, Swift World!")
                try logger.write("swift quickstart responded with 200")
                try await res.status(200).send(content)
                try logger.write("swift quickstart responded with 404")
                try await res.status(404).send()


  1. SwiftWasm toolchain
  2. Fastly CLI


$ fastly compute init
$ /Library/Developer/Toolchains/swift-wasm-5.6.0-RELEASE.xctoolchain/usr/bin/swift build --triple wasm32-unknown-wasi --product FastlyComputeQuickstart -c release
$ fastly compute pack --wasm-binary=./.build/release/FastlyComputeQuickstart.wasm
$ fastly compute deploy


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