feat: use the deployment's hostname suffix in the UI (#133)

Closes #93.

<img width="272" alt="image" src="https://github.com/user-attachments/assets/54786bea-9d32-432f-9869-5abd42a86516" />


The only time the hostname suffix is used by the desktop app is when an offline workspace needs to be shown in the list, where we naively append `.coder`. This PR sets this appended value to whatever `--workspace-hostname-suffix` is configured to deployment-side.

We read the config value from the deployment when:
- The app is launched, if the user is signed in.
- The user signs in.
- The VPN is started.

Author: ethanndickson

Diff for: Coder-Desktop/Coder-Desktop/Coder_DesktopApp.swift

@@ -41,10 +41,15 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     override init() {
         vpn = CoderVPNService()
-        state = AppState(onChange: vpn.configureTunnelProviderProtocol)
+        let state = AppState(onChange: vpn.configureTunnelProviderProtocol)
+        vpn.onStart = {
+            // We don't need this to have finished before the VPN actually starts
+            Task { await state.refreshDeploymentConfig() }
+        }
         if state.startVPNOnLaunch {
             vpn.startWhenReady = true
         }
+        self.state = state
         vpn.installSystemExtension()
         #if arch(arm64)
             let mutagenBinary = "mutagen-darwin-arm64"

Diff for: Coder-Desktop/Coder-Desktop/State.swift

@@ -25,6 +25,10 @@ class AppState: ObservableObject {
         }
     }
 
+    @Published private(set) var hostnameSuffix: String = defaultHostnameSuffix
+
+    static let defaultHostnameSuffix: String = "coder"
+
     // Stored in Keychain
     @Published private(set) var sessionToken: String? {
         didSet {
@@ -33,6 +37,8 @@ class AppState: ObservableObject {
         }
     }
 
+    private var client: Client?
+
     @Published var useLiteralHeaders: Bool = UserDefaults.standard.bool(forKey: Keys.useLiteralHeaders) {
         didSet {
             reconfigure()
@@ -80,7 +86,7 @@ class AppState: ObservableObject {
     private let keychain: Keychain
     private let persistent: Bool
 
-    let onChange: ((NETunnelProviderProtocol?) -> Void)?
+    private let onChange: ((NETunnelProviderProtocol?) -> Void)?
 
     // reconfigure must be called when any property used to configure the VPN changes
     public func reconfigure() {
@@ -107,21 +113,35 @@ class AppState: ObservableObject {
             if sessionToken == nil || sessionToken!.isEmpty == true {
                 clearSession()
             }
+            client = Client(
+                url: baseAccessURL!,
+                token: sessionToken!,
+                headers: useLiteralHeaders ? literalHeaders.map { $0.toSDKHeader() } : []
+            )
+            Task {
+                await handleTokenExpiry()
+                await refreshDeploymentConfig()
+            }
         }
     }
 
     public func login(baseAccessURL: URL, sessionToken: String) {
         hasSession = true
         self.baseAccessURL = baseAccessURL
         self.sessionToken = sessionToken
+        client = Client(
+            url: baseAccessURL,
+            token: sessionToken,
+            headers: useLiteralHeaders ? literalHeaders.map { $0.toSDKHeader() } : []
+        )
+        Task { await refreshDeploymentConfig() }
         reconfigure()
     }
 
     public func handleTokenExpiry() async {
         if hasSession {
-            let client = Client(url: baseAccessURL!, token: sessionToken!)
             do {
-                _ = try await client.user("me")
+                _ = try await client!.user("me")
             } catch let SDKError.api(apiErr) {
                 // Expired token
                 if apiErr.statusCode == 401 {
@@ -135,9 +155,34 @@ class AppState: ObservableObject {
         }
     }
 
+    private var refreshTask: Task<String?, Never>?
+    public func refreshDeploymentConfig() async {
+        // Client is non-nil if there's a sesssion
+        if hasSession, let client {
+            refreshTask?.cancel()
+
+            refreshTask = Task {
+                let res = try? await retry(floor: .milliseconds(100), ceil: .seconds(10)) {
+                    do {
+                        let config = try await client.agentConnectionInfoGeneric()
+                        return config.hostname_suffix
+                    } catch {
+                        logger.error("failed to get agent connection info (retrying): \(error)")
+                        throw error
+                    }
+                }
+                return res
+            }
+
+            hostnameSuffix = await refreshTask?.value ?? Self.defaultHostnameSuffix
+        }
+    }
+
     public func clearSession() {
         hasSession = false
         sessionToken = nil
+        refreshTask?.cancel()
+        client = nil
         reconfigure()
     }
 

Diff for: Coder-Desktop/Coder-Desktop/VPN/VPNService.swift

@@ -76,6 +76,7 @@ final class CoderVPNService: NSObject, VPNService {
 
     // Whether the VPN should start as soon as possible
     var startWhenReady: Bool = false
+    var onStart: (() -> Void)?
 
     // systemExtnDelegate holds a reference to the SystemExtensionDelegate so that it doesn't get
     // garbage collected while the OSSystemExtensionRequest is in flight, since the OS framework
@@ -187,8 +188,11 @@ extension CoderVPNService {
             xpc.connect()
             xpc.ping()
             tunnelState = .connecting
-        // Non-connected -> Connected: Retrieve Peers
+        // Non-connected -> Connected:
+        // - Retrieve Peers
+        // - Run `onStart` closure
         case (_, .connected):
+            onStart?()
             xpc.connect()
             xpc.getPeerState()
             tunnelState = .connected

Diff for: Coder-Desktop/Coder-Desktop/Views/VPN/VPNMenuItem.swift

@@ -42,20 +42,23 @@ enum VPNMenuItem: Equatable, Comparable, Identifiable {
 }
 
 struct MenuItemView: View {
+    @EnvironmentObject var state: AppState
+
     let item: VPNMenuItem
     let baseAccessURL: URL
     @State private var nameIsSelected: Bool = false
     @State private var copyIsSelected: Bool = false
 
     private var itemName: AttributedString {
         let name = switch item {
-        case let .agent(agent): agent.primaryHost ?? "\(item.wsName).coder"
-        case .offlineWorkspace: "\(item.wsName).coder"
+        case let .agent(agent): agent.primaryHost ?? "\(item.wsName).\(state.hostnameSuffix)"
+        case .offlineWorkspace: "\(item.wsName).\(state.hostnameSuffix)"
         }
 
         var formattedName = AttributedString(name)
         formattedName.foregroundColor = .primary
-        if let range = formattedName.range(of: ".coder") {
+
+        if let range = formattedName.range(of: ".\(state.hostnameSuffix)", options: .backwards) {
             formattedName[range].foregroundColor = .secondary
         }
         return formattedName

Diff for: Coder-Desktop/CoderSDK/Util.swift

@@ -0,0 +1,25 @@
+import Foundation
+
+public func retry<T>(
+    floor: Duration,
+    ceil: Duration,
+    rate: Double = 1.618,
+    operation: @Sendable () async throws -> T
+) async throws -> T {
+    var delay = floor
+
+    while !Task.isCancelled {
+        do {
+            return try await operation()
+        } catch let error as CancellationError {
+            throw error
+        } catch {
+            try Task.checkCancellation()
+
+            delay = min(ceil, delay * rate)
+            try await Task.sleep(for: delay)
+        }
+    }
+
+    throw CancellationError()
+}

Diff for: Coder-Desktop/CoderSDK/WorkspaceAgents.swift

@@ -0,0 +1,15 @@
+import Foundation
+
+public extension Client {
+    func agentConnectionInfoGeneric() async throws(SDKError) -> AgentConnectionInfo {
+        let res = try await request("/api/v2/workspaceagents/connection", method: .get)
+        guard res.resp.statusCode == 200 else {
+            throw responseAsError(res)
+        }
+        return try decode(AgentConnectionInfo.self, from: res.data)
+    }
+}
+
+public struct AgentConnectionInfo: Codable, Sendable {
+    public let hostname_suffix: String?
+}