Add new Client API

Signed-off-by: Helder Correia <174525+helderco@users.noreply.github.com>

pkg/dagger.io/dagger/plan.cue

@@ -2,6 +2,37 @@ package dagger
 
 // A special kind of program which `dagger` can execute.
 #Plan: {
+	// Access client machine
+	client: {
+		// Access client filesystem
+		// Path may be absolute, or relative to client working directory
+		filesystem: [path=string]: {
+			// Read data from that path
+			read?: _#clientFilesystemRead & {
+				"path": path
+			}
+
+			// If set, Write to that path
+			write?: _#clientFilesystemWrite & {
+				"path": path
+
+				// avoid race condition
+				if read != _|_ {
+					_after: read
+				}
+			}
+		}
+
+		// Access client environment variables
+		env: [string]: *string | #Secret
+
+		// Execute commands in the client
+		commands: [id=string]: _#clientCommand
+
+		// Platform of the client machine
+		platform: _#clientPlatform
+	}
+
 	// Receive inputs from the client
 	inputs: {
 		// Receive directories
@@ -32,6 +63,84 @@ package dagger
 	}
 }
 
+_#clientFilesystemRead: {
+	$dagger: task: _name: "ClientFilesystemRead"
+
+	// Path may be absolute, or relative to client working directory
+	path: string
+
+	{
+		// CUE type defines expected content:
+		//     string: contents of a regular file
+		//     #Secret: secure reference to the file contents
+		contents: string | #Secret
+	} | {
+		// CUE type defines expected content:
+		//     #FS: contents of a directory
+		contents: #FS
+
+		// Filename patterns to include
+		// Example: ["*.go", "Dockerfile"]
+		include?: [...string]
+
+		// Filename patterns to exclude
+		// Example: ["node_modules"]
+		exclude?: [...string]
+	} | {
+		// CUE type defines expected content:
+		//     #Service: unix socket or npipe
+		contents: #Service
+
+		// Type of service
+		type: *"unix" | "npipe"
+	}
+}
+
+_#clientFilesystemWrite: {
+	$dagger: task: _name: "ClientFilesystemWrite"
+
+	// Path may be absolute, or relative to client working directory
+	path: string
+	{
+		// File contents to export (as a string or secret)
+		contents: string | #Secret
+
+		// File permissions (defaults to 0o644)
+		permissions?: int
+	} | {
+		// Filesystem contents to export
+		// Reference an #FS field produced by an action
+		contents: #FS
+	}
+}
+
+_#clientCommand: {
+	$dagger: task: _name: "ClientCommand"
+
+	name: string
+	args: [...string]
+	flags: [string]: bool | string
+	env: [string]:   string | #Secret
+
+	// Capture standard output (as a string or secret)
+	stdout?: *string | #Secret
+
+	// Capture standard error (as a string or secret)
+	stderr?: *string | #Secret
+
+	// Inject standard input (from a string or secret)
+	stdin?: string | #Secret
+}
+
+_#clientPlatform: {
+	$dagger: task: _name: "ClientPlatform"
+
+	// Operating system of the client machine
+	os: string
+	// Hardware architecture of the client machine
+	arch: string
+}
+
 _#inputDirectory: {
 	// FIXME: rename to "InputDirectory" for consistency
 	$dagger: task: _name: "InputDirectory"