[volumes]: refactor prune command (apple#940)

- Refactor the `volume prune` command to follow a client-side approach.
  The `volumeDiskUsage` is calculated in the service file, so it made
  sense to leave that there.
- Relates to the discussion from apple#914

Author: saehejkang

Sources/ContainerClient/Core/ClientVolume.swift

@@ -81,18 +81,13 @@ public struct ClientVolume {
         return try JSONDecoder().decode(Volume.self, from: responseData)
     }
 
-    public static func prune() async throws -> ([String], UInt64) {
+    public static func volumeDiskUsage(name: String) async throws -> UInt64 {
         let client = XPCClient(service: serviceIdentifier)
-        let message = XPCMessage(route: .volumePrune)
+        let message = XPCMessage(route: .volumeDiskUsage)
+        message.set(key: .volumeName, value: name)
         let reply = try await client.send(message)
 
-        guard let responseData = reply.dataNoCopy(key: .volumes) else {
-            return ([], 0)
-        }
-
-        let volumeNames = try JSONDecoder().decode([String].self, from: responseData)
         let size = reply.uint64(key: .volumeSize)
-        return (volumeNames, size)
+        return size
     }
-
 }

Sources/ContainerClient/Core/XPC+.swift

@@ -155,8 +155,8 @@ public enum XPCRoute: String {
     case volumeDelete
     case volumeList
     case volumeInspect
-    case volumePrune
 
+    case volumeDiskUsage
     case systemDiskUsage
 
     case ping

Sources/ContainerCommands/Volume/VolumePrune.swift

@@ -29,19 +29,43 @@ extension Application.VolumeCommand {
         var global: Flags.Global
 
         public func run() async throws {
-            let (volumeNames, size) = try await ClientVolume.prune()
-            let formatter = ByteCountFormatter()
-            let freed = formatter.string(fromByteCount: Int64(size))
-
-            if volumeNames.isEmpty {
-                print("No volumes to prune")
-            } else {
-                print("Pruned volumes:")
-                for name in volumeNames {
-                    print(name)
+            let allVolumes = try await ClientVolume.list()
+
+            // Find all volumes not used by any container
+            let containers = try await ClientContainer.list()
+            var volumesInUse = Set<String>()
+            for container in containers {
+                for mount in container.configuration.mounts {
+                    if mount.isVolume, let volumeName = mount.volumeName {
+                        volumesInUse.insert(volumeName)
+                    }
+                }
+            }
+
+            let volumesToPrune = allVolumes.filter { volume in
+                !volumesInUse.contains(volume.name)
+            }
+
+            var prunedVolumes = [String]()
+            var totalSize: UInt64 = 0
+
+            for volume in volumesToPrune {
+                do {
+                    let actualSize = try await ClientVolume.volumeDiskUsage(name: volume.name)
+                    totalSize += actualSize
+                    try await ClientVolume.delete(name: volume.name)
+                    prunedVolumes.append(volume.name)
+                } catch {
+                    log.error("Failed to prune volume \(volume.name): \(error)")
                 }
-                print()
             }
+
+            for name in prunedVolumes {
+                print(name)
+            }
+
+            let formatter = ByteCountFormatter()
+            let freed = formatter.string(fromByteCount: Int64(totalSize))
             print("Reclaimed \(freed) in disk space")
         }
     }

Sources/Helpers/APIServer/APIServer+Start.swift

@@ -271,7 +271,7 @@ extension APIServer {
             routes[XPCRoute.volumeDelete] = harness.delete
             routes[XPCRoute.volumeList] = harness.list
             routes[XPCRoute.volumeInspect] = harness.inspect
-            routes[XPCRoute.volumePrune] = harness.prune
+            routes[XPCRoute.volumeDiskUsage] = harness.diskUsage
 
             return service
         }

Sources/Services/ContainerAPIService/Volumes/VolumesHarness.swift

@@ -94,12 +94,13 @@ public struct VolumesHarness: Sendable {
     }
 
     @Sendable
-    public func prune(_ message: XPCMessage) async throws -> XPCMessage {
-        let (volumeNames, size) = try await service.prune()
-        let data = try JSONEncoder().encode(volumeNames)
+    public func diskUsage(_ message: XPCMessage) async throws -> XPCMessage {
+        guard let name = message.string(key: .volumeName) else {
+            throw ContainerizationError(.invalidArgument, message: "volume name cannot be empty")
+        }
+        let size = try await service.volumeDiskUsage(name: name)
 
         let reply = message.reply()
-        reply.set(key: .volumes, value: data)
         reply.set(key: .volumeSize, value: size)
         return reply
     }

Sources/Services/ContainerAPIService/Volumes/VolumesService.swift

@@ -72,48 +72,10 @@ public actor VolumesService {
         }
     }
 
-    public func prune() async throws -> ([String], UInt64) {
-        try await lock.withLock { _ in
-            let allVolumes = try await self.store.list()
-
-            // do entire prune operation atomically with container list
-            return try await self.containersService.withContainerList { containers in
-                var inUseSet = Set<String>()
-                for container in containers {
-                    for mount in container.configuration.mounts {
-                        if mount.isVolume, let volumeName = mount.volumeName {
-                            inUseSet.insert(volumeName)
-                        }
-                    }
-                }
-
-                let volumesToPrune = allVolumes.filter { volume in
-                    !inUseSet.contains(volume.name)
-                }
-
-                var prunedNames = [String]()
-                var totalSize: UInt64 = 0
-
-                for volume in volumesToPrune {
-                    do {
-                        // calculate actual disk usage before deletion
-                        let volumePath = self.volumePath(for: volume.name)
-                        let actualSize = self.calculateDirectorySize(at: volumePath)
-
-                        try await self.store.delete(volume.name)
-                        try self.removeVolumeDirectory(for: volume.name)
-
-                        prunedNames.append(volume.name)
-                        totalSize += actualSize
-                        self.log.info("Pruned volume", metadata: ["name": "\(volume.name)", "size": "\(actualSize)"])
-                    } catch {
-                        self.log.error("failed to prune volume \(volume.name): \(error)")
-                    }
-                }
-
-                return (prunedNames, totalSize)
-            }
-        }
+    /// Calculate disk usage for a single volume
+    public func volumeDiskUsage(name: String) async throws -> UInt64 {
+        let volumePath = self.volumePath(for: name)
+        return self.calculateDirectorySize(at: volumePath)
     }
 
     /// Calculate disk usage for volumes

Tests/CLITests/Subcommands/Volumes/TestCLIVolumes.swift

@@ -332,7 +332,7 @@ class TestCLIVolumes: CLITest {
             throw CLIError.executionFailed("volume prune failed: \(error)")
         }
 
-        #expect(output.contains("0 B") || output.contains("No volumes to prune"), "should show no space reclaimed or no volumes message")
+        #expect(output.contains("Zero KB"), "should show no space reclaimed")
     }
 
     @Test func testVolumePruneUnusedVolumes() throws {