container build support inline Dockerfile from stdin

Author: saehejkang

Sources/ContainerCommands/BuildCommand.swift

@@ -186,7 +186,34 @@ extension Application {
                     throw ValidationError("builder is not running")
                 }
 
-                let dockerfile = try Data(contentsOf: URL(filePath: file))
+                let dockerfile: Data
+                let tempFile = FileManager.default.temporaryDirectory.appendingPathComponent("TempDockerfile")
+                defer {
+                    try? FileManager.default.removeItem(at: tempFile)
+                }
+                
+                // Dockerfile should be read from stdin
+                if file == "-" {
+                    guard FileManager.default.createFile(atPath: tempFile.path(), contents: nil) else {
+                        throw ContainerizationError(.internalError, message: "unable to create temporary file")
+                    }
+
+                    guard let outputHandle = try? FileHandle(forWritingTo: tempFile) else {
+                        throw ContainerizationError(.internalError, message: "unable to open temporary file for writing")
+                    }
+
+                    let bufferSize = 4096
+                    while true {
+                        let chunk = FileHandle.standardInput.readData(ofLength: bufferSize)
+                        if chunk.isEmpty { break }
+                        outputHandle.write(chunk)
+                    }
+                    try outputHandle.close()
+                    dockerfile = try Data(contentsOf: URL(filePath: tempFile.path()))
+                } else {
+                    dockerfile = try Data(contentsOf: URL(filePath: file))
+                }
+
                 let systemHealth = try await ClientHealthCheck.ping(timeout: .seconds(10))
                 let exportPath = systemHealth.appRoot
                     .appendingPathComponent(Application.BuilderCommand.builderResourceDir)
@@ -351,7 +378,7 @@ extension Application {
         }
 
         public func validate() throws {
-            guard FileManager.default.fileExists(atPath: file) else {
+            guard FileManager.default.fileExists(atPath: file) || file == "-" else {
                 throw ValidationError("Dockerfile does not exist at path: \(file)")
             }
             guard FileManager.default.fileExists(atPath: contextDir) else {