Download toolchains using proxy if one is set in the environment (#189)

Swiftly doesn't currently handle the standard HTTP proxy server environment variables when making its network connections. It only handles it as a necessity in the current macOS CI environment and only in the tests. Make the built-in http executor read these environment variables if they are present and use those for all http requests. Add documentation in the GSG showing how to use this feature.

Author: vsarunas

Documentation/SwiftlyDocs.docc/getting-started.md

@@ -58,6 +58,17 @@ Uninstall this toolchain after you're finished with it:
 $ swiftly uninstall main-snapshot
 ```
 
+# Proxy
+
+Swiftly downloads a list of toolchains from https://www.swift.org/ and retrieves them from Apple/Akamai CDN via https://download.swift.org.
+If your environment requires a proxy, Swiftly will attempt to use the standard environment variables `http_proxy`, `HTTP_PROXY`, `https_proxy` or `HTTPS_PROXY` to determine which proxy server to use instead of making a direct connection.
+
+To download latest nightly snapshot using a proxy:
+```
+$ export https_proxy=http://proxy:3128
+$ swiftly install main-snapshot
+```
+
 # See Also:
 
 - [Install Toolchains](install-toolchains)

Sources/SwiftlyCore/HTTPClient.swift

@@ -10,9 +10,48 @@ public protocol HTTPRequestExecutor {
 }
 
 /// An `HTTPRequestExecutor` backed by the shared `HTTPClient`.
-internal struct HTTPRequestExecutorImpl: HTTPRequestExecutor {
+internal class HTTPRequestExecutorImpl: HTTPRequestExecutor {
+    let httpClient: HTTPClient
+
+    public init() {
+        var proxy: HTTPClient.Configuration.Proxy?
+
+        func getProxyFromEnv(keys: [String]) -> HTTPClient.Configuration.Proxy? {
+            let environment = ProcessInfo.processInfo.environment
+            for key in keys {
+                if let proxyString = environment[key],
+                   let url = URL(string: proxyString),
+                   let host = url.host,
+                   let port = url.port
+                {
+                    return .server(host: host, port: port)
+                }
+            }
+            return nil
+        }
+
+        if let httpProxy = getProxyFromEnv(keys: ["http_proxy", "HTTP_PROXY"]) {
+            proxy = httpProxy
+        }
+        if let httpsProxy = getProxyFromEnv(keys: ["https_proxy", "HTTPS_PROXY"]) {
+            proxy = httpsProxy
+        }
+
+        if proxy != nil {
+            self.httpClient = HTTPClient(eventLoopGroupProvider: .singleton, configuration: HTTPClient.Configuration(proxy: proxy))
+        } else {
+            self.httpClient = HTTPClient.shared
+        }
+    }
+
+    deinit {
+        if httpClient !== HTTPClient.shared {
+            try? httpClient.syncShutdown()
+        }
+    }
+
     public func execute(_ request: HTTPClientRequest, timeout: TimeAmount) async throws -> HTTPClientResponse {
-        try await HTTPClient.shared.execute(request, timeout: timeout)
+        try await self.httpClient.execute(request, timeout: timeout)
     }
 }
 

Tests/SwiftlyTests/SwiftlyTests.swift

@@ -17,51 +17,7 @@ struct SwiftlyTestError: LocalizedError {
     let message: String
 }
 
-var proxyExecutorInstalled = false
-
-/// An `HTTPRequestExecutor` backed by an `HTTPClient` that can take http proxy
-/// information from the environment in either HTTP_PROXY or HTTPS_PROXY
-class ProxyHTTPRequestExecutorImpl: HTTPRequestExecutor {
-    let httpClient: HTTPClient
-    public init() {
-        var proxy: HTTPClient.Configuration.Proxy?
-
-        let environment = ProcessInfo.processInfo.environment
-        let httpProxy = environment["HTTP_PROXY"]
-        if let httpProxy, let url = URL(string: httpProxy), let host = url.host, let port = url.port {
-            proxy = .server(host: host, port: port)
-        }
-
-        let httpsProxy = environment["HTTPS_PROXY"]
-        if let httpsProxy, let url = URL(string: httpsProxy), let host = url.host, let port = url.port {
-            proxy = .server(host: host, port: port)
-        }
-
-        if proxy != nil {
-            self.httpClient = HTTPClient(eventLoopGroupProvider: .singleton, configuration: HTTPClient.Configuration(proxy: proxy))
-        } else {
-            self.httpClient = HTTPClient.shared
-        }
-    }
-
-    public func execute(_ request: HTTPClientRequest, timeout: TimeAmount) async throws -> HTTPClientResponse {
-        try await self.httpClient.execute(request, timeout: timeout)
-    }
-
-    deinit {
-        if httpClient !== HTTPClient.shared {
-            try? httpClient.syncShutdown()
-        }
-    }
-}
-
 class SwiftlyTests: XCTestCase {
-    override class func setUp() {
-        if !proxyExecutorInstalled {
-            SwiftlyCore.httpRequestExecutor = ProxyHTTPRequestExecutorImpl()
-        }
-    }
-
     override class func tearDown() {
 #if os(Linux)
         let deleteTestGPGKeys = Process()