tart run: introduce --net-softnet-expose (#990)

* tart run: introduce --net-softnet-expose

* --net-softnet-expose: add discussion

* --net-softnet-expose: add a note about Softnet restrictions

...and how to disable them.

* LAN → local network

* Better clarify what --net-softnet does

And how --net-softnet-allow can change that behavior.

Sources/tart/Commands/Run.swift

@@ -183,13 +183,42 @@ struct Run: AsyncParsableCommand {
   """, valueName: "interface name"))
   var netBridged: [String] = []
 
-  @Flag(help: ArgumentHelp("Use software networking instead of the default shared (NAT) networking",
-                           discussion: "Learn how to configure Softnet for use with Tart here: https://github.com/cirruslabs/softnet"))
+  @Flag(help: ArgumentHelp("Use software networking provided by Softnet instead of the default shared (NAT) networking",
+                           discussion: """
+                           Softnet provides better network isolation and alleviates DHCP shortage on production systems. Tart invokes Softnet when this option is specified as a sub-process and communicates with it over socketpair(2).
+
+                           It is essentially a userspace packet filter which restricts the VM networking and prevents a class of security issues, such as ARP spoofing. By default, the VM will only be able to:
+
+                           * send traffic from its own MAC-address
+                           * send traffic from the IP-address assigned to it by the DHCP
+                           * send traffic to globally routable IPv4 addresses
+                           * send traffic to gateway IP of the vmnet bridge (this would normally be \"bridge100\" interface)
+                           * receive any incoming traffic
+
+                           In addition, Softnet tunes macOS built-in DHCP server to decrease its lease time from the default 86,400 seconds (one day) to 600 seconds (10 minutes). This is especially important when you use Tart to clone and run a lot of ephemeral VMs over a period of one day.
+
+                           More on Softnet here: https://github.com/cirruslabs/softnet
+                           """))
   var netSoftnet: Bool = false
 
-  @Option(help: ArgumentHelp("Comma-separated list of CIDRs to allow the traffic to when using Softnet isolation\n(e.g. --net-softnet-allow=192.168.0.0/24)", valueName: "comma-separated CIDRs"))
+  @Option(help: ArgumentHelp("Comma-separated list of CIDRs to allow the traffic to when using Softnet isolation\n(e.g. --net-softnet-allow=192.168.0.0/24)", discussion: """
+  This option allows you bypass the private IPv4 address space restrctions imposed by --net-softnet.
+
+  For example, you can allow the VM to communicate with the local network with e.g. --net-softnet-allow=10.0.0.0/16 or to completely disable the destination based restrictions with --net-softnet-allow=0.0.0.0/0.
+  """, valueName: "comma-separated CIDRs"))
   var netSoftnetAllow: String?
 
+  @Option(help: ArgumentHelp("Comma-separated list of TCP ports to expose (e.g. --net-softnet-expose 2222:22,8080:80)", discussion: """
+  Options are comma-separated and are as follows:
+
+  * EXTERNAL_PORT:INTERNAL_PORT — forward TCP traffic from the EXTERNAL_PORT on a host's egress interface (automatically detected and could be Wi-Fi, Ethernet and a VPN interface) to the INTERNAL_PORT on guest's IP (as reported by "tart ip")
+
+  Note that your software should either listen on 0.0.0.0 inside of a VM or on an IP address assigned to that VM for the port forwarding to work correctly.
+
+  Another thing to keep in mind is that regular Softnet restrictions will still apply even to port forwarding. So if you're planning to access your VM from local network, and your local network is 192.168.0.0/24, for example, then add --net-softnet-allow=192.168.0.0/24. If you only need port forwarding, to completely disable Softnet restrictions you can use --net-softnet-allow=0.0.0.0/0.
+  """, valueName: "comma-separated port specifications"))
+  var netSoftnetExpose: String?
+
   @Flag(help: ArgumentHelp("Restrict network access to the host-only network"))
   var netHost: Bool = false
 
@@ -527,6 +556,10 @@ struct Run: AsyncParsableCommand {
       softnetExtraArguments += ["--allow", netSoftnetAllow]
     }
 
+    if let netSoftnetExpose = netSoftnetExpose {
+      softnetExtraArguments += ["--expose", netSoftnetExpose]
+    }
+
     if netSoftnet {
       let config = try VMConfig.init(fromURL: vmDir.configURL)
 

Sources/tart/Fetcher.swift

@@ -17,7 +17,7 @@ fileprivate var urlSession: URLSession = {
 }()
 
 class Fetcher {
-  static func fetch(_ request: URLRequest, viaFile: Bool = false, progress: Progress? = nil) async throws -> (AsyncThrowingStream<Data, Error>, HTTPURLResponse) {
+  static func fetch(_ request: URLRequest, viaFile: Bool = false) async throws -> (AsyncThrowingStream<Data, Error>, HTTPURLResponse) {
     let task = urlSession.dataTask(with: request)
 
     let delegate = Delegate()

Sources/tart/OCI/Layerizer/DiskV2.swift

@@ -44,7 +44,7 @@ class DiskV2: Disk {
           let compressedData = try (data as NSData).compressed(using: .lz4) as Data
           let compressedDataDigest = Digest.hash(compressedData)
 
-          try await retry(maxAttempts: 5, backoff: .exponentialWithFullJitter(baseDelay: .seconds(5), maxDelay: .seconds(60))) {
+          try await retry(maxAttempts: 5) {
             if try await !registry.blobExists(compressedDataDigest) {
               _ = try await registry.pushBlob(fromData: compressedData, chunkSizeMb: chunkSizeMb, digest: compressedDataDigest)
             }
@@ -208,11 +208,26 @@ class DiskV2: Disk {
             diskWritingOffset = try zeroSkippingWrite(disk, rdisk, fsBlockSize, diskWritingOffset, data)
           }
 
-          try await registry.pullBlob(diskLayer.digest) { data in
-            try filter.write(data)
+          var rangeStart: Int64 = 0
 
-            // Update the progress
-            progress.completedUnitCount += Int64(data.count)
+          try await retry(maxAttempts: 5) {
+            try await registry.pullBlob(diskLayer.digest, rangeStart: rangeStart) { data in
+              try filter.write(data)
+
+              // Update the progress
+              progress.completedUnitCount += Int64(data.count)
+
+              // Update the current range start
+              rangeStart += Int64(data.count)
+            }
+          } recoverFromFailure: { error in
+            if error is URLError {
+              print("Error pulling disk layer \(index + 1): \"\(error.localizedDescription)\", attempting to re-try...")
+
+              return .retry
+            }
+
+            return .throw
           }
 
           try filter.finalize()

Sources/tart/OCI/Registry.swift

@@ -20,6 +20,7 @@ enum HTTPCode: Int {
   case Ok = 200
   case Created = 201
   case Accepted = 202
+  case PartialContent = 206
   case Unauthorized = 401
   case NotFound = 404
 }
@@ -28,14 +29,26 @@ extension Data {
   func asText() -> String {
     String(decoding: self, as: UTF8.self)
   }
+
+  func asTextPreview(limit: Int = 1000) -> String {
+    guard count > limit else {
+      return asText()
+    }
+
+    return "\(asText().prefix(limit))..."
+  }
 }
 
 extension AsyncThrowingStream<Data, Error> {
-  func asData() async throws -> Data {
+  func asData(limitBytes: Int64? = nil) async throws -> Data {
     var result = Data()
 
     for try await chunk in self {
       result += chunk
+
+      if let limitBytes, result.count > limitBytes {
+        return result
+      }
     }
 
     return result
@@ -159,7 +172,7 @@ class Registry {
                                                  body: manifestJSON)
     if response.statusCode != HTTPCode.Created.rawValue {
       throw RegistryError.UnexpectedHTTPStatusCode(when: "pushing manifest", code: response.statusCode,
-                                                   details: data.asText())
+                                                   details: data.asTextPreview())
     }
 
     return Digest.hash(manifestJSON)
@@ -170,7 +183,7 @@ class Registry {
                                                  headers: ["Accept": ociManifestMediaType])
     if response.statusCode != HTTPCode.Ok.rawValue {
       throw RegistryError.UnexpectedHTTPStatusCode(when: "pulling manifest", code: response.statusCode,
-                                                   details: data.asText())
+                                                   details: data.asTextPreview())
     }
 
     let manifest = try OCIManifest(fromJSON: data)
@@ -196,7 +209,7 @@ class Registry {
                                                      headers: ["Content-Length": "0"])
     if postResponse.statusCode != HTTPCode.Accepted.rawValue {
       throw RegistryError.UnexpectedHTTPStatusCode(when: "pushing blob (POST)", code: postResponse.statusCode,
-                                                   details: data.asText())
+                                                   details: data.asTextPreview())
     }
 
     // Figure out where to upload the blob
@@ -217,7 +230,7 @@ class Registry {
       )
       if response.statusCode != HTTPCode.Created.rawValue {
         throw RegistryError.UnexpectedHTTPStatusCode(when: "pushing blob (PUT) to \(uploadLocation)",
-                                                     code: response.statusCode, details: data.asText())
+                                                     code: response.statusCode, details: data.asTextPreview())
       }
       return digest
     }
@@ -240,7 +253,7 @@ class Registry {
       // always accept both statuses since AWS ECR is not following specification
       if response.statusCode != HTTPCode.Created.rawValue && response.statusCode != HTTPCode.Accepted.rawValue {
         throw RegistryError.UnexpectedHTTPStatusCode(when: "streaming blob to \(uploadLocation)",
-                                                     code: response.statusCode, details: data.asText())
+                                                     code: response.statusCode, details: data.asTextPreview())
       }
       uploadedBytes += chunk.count
       // Update location for the next chunk
@@ -259,14 +272,26 @@ class Registry {
     case HTTPCode.NotFound.rawValue:
       return false
     default:
-      throw RegistryError.UnexpectedHTTPStatusCode(when: "checking blob", code: response.statusCode, details: data.asText())
+      throw RegistryError.UnexpectedHTTPStatusCode(when: "checking blob", code: response.statusCode, details: data.asTextPreview())
     }
   }
 
-  public func pullBlob(_ digest: String, handler: (Data) async throws -> Void) async throws {
-    let (channel, response) = try await channelRequest(.GET, endpointURL("\(namespace)/blobs/\(digest)"), viaFile: true)
-    if response.statusCode != HTTPCode.Ok.rawValue {
-      let body = try await channel.asData().asText()
+  public func pullBlob(_ digest: String, rangeStart: Int64 = 0, handler: (Data) async throws -> Void) async throws {
+    var expectedStatusCode = HTTPCode.Ok
+    var headers: [String: String] = [:]
+
+    // Send Range header and expect HTTP 206 in return
+    //
+    // However, do not send Range header at all when rangeStart is 0,
+    // because it makes no sense and we might get HTTP 200 in return
+    if rangeStart != 0 {
+      expectedStatusCode = HTTPCode.PartialContent
+      headers["Range"] = "bytes=\(rangeStart)-"
+    }
+
+    let (channel, response) = try await channelRequest(.GET, endpointURL("\(namespace)/blobs/\(digest)"), headers: headers, viaFile: true)
+    if response.statusCode != expectedStatusCode.rawValue {
+      let body = try await channel.asData(limitBytes: 4096).asTextPreview()
       throw RegistryError.UnexpectedHTTPStatusCode(when: "pulling blob", code: response.statusCode,
                                                    details: body)
     }
@@ -329,7 +354,6 @@ class Registry {
     var (channel, response) = try await authAwareRequest(request: request, viaFile: viaFile, doAuth: doAuth)
 
     if doAuth && response.statusCode == HTTPCode.Unauthorized.rawValue {
-      _ = try await channel.asData()
       try await auth(response: response)
       (channel, response) = try await authAwareRequest(request: request, viaFile: viaFile, doAuth: doAuth)
     }
@@ -391,7 +415,7 @@ class Registry {
     let (data, response) = try await dataRequest(.GET, authenticateURL, headers: headers, doAuth: false)
     if response.statusCode != HTTPCode.Ok.rawValue {
       throw RegistryError.AuthFailed(why: "received unexpected HTTP status code \(response.statusCode) "
-        + "while retrieving an authentication token", details: data.asText())
+        + "while retrieving an authentication token", details: data.asTextPreview())
     }
 
     await authenticationKeeper.set(try TokenResponse.parse(fromData: data))

Sources/tart/VM.swift

@@ -99,16 +99,13 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     // Download the IPSW
     defaultLogger.appendNewLine("Fetching \(remoteURL.lastPathComponent)...")
 
-    let downloadProgress = Progress(totalUnitCount: 100)
-    ProgressObserver(downloadProgress).log(defaultLogger)
-
     let request = URLRequest(url: remoteURL)
-    let (channel, response) = try await Fetcher.fetch(request, viaFile: true, progress: downloadProgress)
+    let (channel, response) = try await Fetcher.fetch(request, viaFile: true)
 
     let temporaryLocation = try Config().tartTmpDir.appendingPathComponent(UUID().uuidString + ".ipsw")
-    defaultLogger.appendNewLine("Computing digest for \(temporaryLocation.path)...")
-    let digestProgress = Progress(totalUnitCount: response.expectedContentLength)
-    ProgressObserver(digestProgress).log(defaultLogger)
+
+    let progress = Progress(totalUnitCount: response.expectedContentLength)
+    ProgressObserver(progress).log(defaultLogger)
 
     FileManager.default.createFile(atPath: temporaryLocation.path, contents: nil)
     let lock = try FileLock(lockURL: temporaryLocation)
@@ -118,10 +115,9 @@ class VM: NSObject, VZVirtualMachineDelegate, ObservableObject {
     let digest = Digest()
 
     for try await chunk in channel {
-      let chunkAsData = Data(chunk)
-      fileHandle.write(chunkAsData)
-      digest.update(chunkAsData)
-      digestProgress.completedUnitCount += Int64(chunk.count)
+      fileHandle.write(chunk)
+      digest.update(chunk)
+      progress.completedUnitCount += Int64(chunk.count)
     }
 
     try fileHandle.close()

Sources/tart/VMStorageOCI.swift

@@ -196,7 +196,7 @@ class VMStorageOCI: PrunableStorage {
       }
 
       try await withTaskCancellationHandler(operation: {
-        try await retry(maxAttempts: 5, backoff: .exponentialWithFullJitter(baseDelay: .seconds(5), maxDelay: .seconds(60))) {
+        try await retry(maxAttempts: 5) {
           // Choose the best base image which has the most deduplication ratio
           let localLayerCache = try await chooseLocalLayerCache(name, manifest, registry)
 
@@ -213,8 +213,7 @@ class VMStorageOCI: PrunableStorage {
           try await tmpVMDir.pullFromRegistry(registry: registry, manifest: manifest, concurrency: concurrency, localLayerCache: localLayerCache, deduplicate: deduplicate)
         } recoverFromFailure: { error in
           if error is URLError {
-            print("Error: \(error.localizedDescription)")
-            print("Attempting to re-try...")
+            print("Error pulling image: \"\(error.localizedDescription)\", attempting to re-try...")
 
             return .retry
           }

docs/faq.md

@@ -5,6 +5,16 @@ title: Frequently Asked Questions
 description: Advanced configuration and troubleshooting tips for advanced configurations.
 ---
 
+## Troubleshooting crashes
+
+If you experience a crash or encounter another error while using the tart executable, you can collect debug information to assist with troubleshooting. Run the following command in a separate terminal window to gather logs from the Tart process and the macOS Virtualization subsystem:
+
+```shell
+log stream --predicate='process=="tart" OR process CONTAINS "Virtualization"' > tart.log
+```
+
+While the events are being streamed, attempt to reproduce the issue. Once the issue is reproduced, stop the streaming by pressing Ctrl+C. Then, attach the tart.log file to your report.
+
 ## VM location on disk
 
 Tart stores all its files in `~/.tart/` directory. Local images that you can run are stored in `~/.tart/vms/`.
@@ -13,12 +23,12 @@ Remote images are pulled into `~/.tart/cache/OCIs/`.
 ## Nested virtualization support?
 
 Tart is limited by functionality of Apple's `Virtualization.Framework`. At the moment `Virtualization.Framework`
-doesn't support nested virtualization.
+supports nested virtualization only on M3 or M4 chips running macOS 15 (Sequoia). By default, it is disabled, but can be enabled by passing the `--nested` flag to `tart run`.
 
 ## Connecting to a service running on host
 
 To connect from within a virtual machine to a service running on the host machine
-please first make sure that the service is binded to `0.0.0.0`.
+please first make sure that the service is bound to `0.0.0.0`.
 
 Then from within a virtual machine you can access the service using the router's IP address that you can get either from `Preferences -> Network`
 or by running the following command in the Terminal:
@@ -29,7 +39,7 @@ netstat -nr | grep default | head -n 1 | awk '{print $2}'
 
 Note: that accessing host is only possible with the default NAT network. If you are running your virtual machines with
 [Softnet](https://github.com/cirruslabs/softnet) (via `tart run --net-softnet <VM NAME>)`, then the network isolation
-is stricter and it's not only possible to access the host.
+is stricter and it's not possible to access the host.
 
 ## Changing the default NAT subnet
 
@@ -97,7 +107,7 @@ or features supported. If there is some feature missing please don't hesitate to
 Instead of Anka Registry, Tart can work with any OCI-compatible container registry. This provides a much more consistent
 and scalable experience for distributing virtual machines.
 
-Tart doesn't yet have an analogue of Anka Controller for managing long living VMs but [soon will be](https://github.com/cirruslabs/tart/issues/372).
+Tart does have an analogue of Anka Controller for managing VMs across a cluster of Mac hosts called [Orchard](orchard/quick-start.md).
 
 ## Automatic pruning
 

docs/integrations/vm-management.md

@@ -7,7 +7,7 @@ description: Use Packer to build custom VM images, configure VMs and work with r
 
 ## Creating from scratch
 
-Tart supports macOS and Linux virtual machines. All commands like `run` and `pull` work the same way regarding of the underlying OS a particular VM image has.
+Tart supports macOS and Linux virtual machines. All commands like `run` and `pull` work the same way regardless of the underlying OS a particular VM image has.
 The only difference is how such VM images are created. Please check sections below for [macOS](#creating-a-macos-vm-image-from-scratch) and [Linux](#creating-a-linux-vm-image-from-scratch) instructions.
 
 ### Creating a macOS VM image from scratch

docs/orchard/deploying-controller.md

@@ -31,7 +31,13 @@ gcloud compute addresses create orchard-ip --region=us-central1
 export ORCHARD_IP=$(gcloud compute addresses describe orchard-ip --format='value(address)' --region=us-central1)
 ```
 
-Once we have the IP address, we can create a new instance with Orchard Controller running inside a container:
+Then, ensure that there exist a firewall rule targeting `https-server` tag and allowing access to TCP port 443. If that's not the case, create one:
+
+```shell
+gcloud compute firewall-rules create default-allow-https --direction=INGRESS --priority=1000 --network=default --action=ALLOW --rules=tcp:443 --source-ranges=0.0.0.0/0 --target-tags=https-server
+```
+
+Once we have the IP address and the firewall rule set up, we can create a new instance with Orchard Controller running inside a container:
 
 ```bash
 gcloud compute instances create-with-container orchard-controller \