SDK docs

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

docs/sdk.md

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+# Using docker/compose SDK
+
+The `docker/compose` package can be used as a Go library by third-party applications to programmatically manage
+containerized applications defined in Compose files. This SDK provides a comprehensive API that enables developers to
+integrate Compose functionality directly into their applications, allowing them to load, validate, and manage
+multi-container environments without relying on the Compose CLI. Whether you need to orchestrate containers as part of
+a deployment pipeline, build custom management tools, or embed container orchestration into your application, the
+Compose SDK offers the same powerful capabilities that drive the Docker Compose command-line tool.
+
+## Setup the SDK
+
+To get started, create an SDK instance using the `NewComposeService()` function, which initializes a service with the
+necessary configuration to interact with the Docker daemon and manage Compose projects. This service instance provides
+methods for all core Compose operations including creating, starting, stopping, and removing containers, as well as
+loading and validating Compose files. The service handles the underlying Docker API interactions and resource
+management, allowing you to focus on your application logic.
+
+## Example Usage
+
+Here's a basic example demonstrating how to load a Compose project and start the services:
+
+```go
+package main
+
+import (
+    "context"
+    "log"
+
+	"github.com/docker/cli/cli/command"
+	"github.com/docker/cli/cli/flags"
+    "github.com/docker/compose/v2/pkg/api"
+    "github.com/docker/compose/v2/pkg/compose"
+)
+
+func main() {
+    ctx := context.Background()
+
+	dockerCLI, err := command.NewDockerCli()
+	if err != nil {
+		log.Fatalf("Failed to create docker CLI: %v", err)
+	}
+	err = dockerCLI.Initialize(flags.ClientOptions{})
+	if err != nil {
+		log.Fatalf("Failed to initialize docker CLI: %v", err)
+	}
+	
+    // Create a new Compose service instance
+    service, err := compose.NewComposeService(dockerCLI)
+    if err != nil {
+        log.Fatalf("Failed to create compose service: %v", err)
+    }
+
+    // Load the Compose project from a compose file
+    project, err := service.LoadProject(ctx, api.ProjectLoadOptions{
+        ConfigPaths: []string{"compose.yaml"},
+        ProjectName: "my-app",
+    })
+    if err != nil {
+        log.Fatalf("Failed to load project: %v", err)
+    }
+
+    // Start the services defined in the Compose file
+    err = service.Up(ctx, project, api.UpOptions{
+        Create: api.CreateOptions{},
+        Start:  api.StartOptions{},
+    })
+    if err != nil {
+        log.Fatalf("Failed to start services: %v", err)
+    }
+
+    log.Printf("Successfully started project: %s", project.Name)
+}
+```
+
+This example demonstrates the core workflow: creating a service instance, loading a project from a Compose file, and
+starting the services. The SDK provides many additional operations for managing the lifecycle of your containerized
+application.
+
+## Customizing the SDK
+
+The `NewComposeService()` function accepts optional `compose.Option` parameters to customize the SDK behavior. These
+options allow you to configure I/O streams, concurrency limits, dry-run mode, and other advanced features:
+
+```go
+    // Create a custom output buffer to capture logs
+    var outputBuffer bytes.Buffer
+
+    // Create a compose service with custom options
+    service, err := compose.NewComposeService(dockerCLI,
+        compose.WithOutputStream(&outputBuffer),          // Redirect output to custom writer
+        compose.WithErrorStream(os.Stderr),               // Use stderr for errors
+        compose.WithMaxConcurrency(4),                    // Limit concurrent operations
+        compose.WithPrompt(compose.AlwaysOkPrompt()),     // Auto-confirm all prompts
+    )
+```
+
+### Available Options
+
+- **`WithOutputStream(io.Writer)`** - Redirect standard output to a custom writer
+- **`WithErrorStream(io.Writer)`** - Redirect error output to a custom writer
+- **`WithInputStream(io.Reader)`** - Provide a custom input stream for interactive prompts
+- **`WithStreams(out, err, in)`** - Set all I/O streams at once
+- **`WithMaxConcurrency(int)`** - Limit the number of concurrent operations against the Docker API
+- **`WithPrompt(Prompt)`** - Customize user confirmation behavior (use `AlwaysOkPrompt()` for non-interactive mode)
+- **`WithDryRun`** - Run operations in dry-run mode without actually applying changes
+- **`WithContextInfo(api.ContextInfo)`** - Set custom Docker context information
+- **`WithProxyConfig(map[string]string)`** - Configure HTTP proxy settings for builds
+- **`WithEventProcessor(progress.EventProcessor)`** - Receive progress events and operation notifications
+
+These options provide fine-grained control over the SDK's behavior, making it suitable for various integration
+scenarios including CLI tools, web services, automation scripts, and testing environments.
+
+## Tracking Operations with EventProcessor
+
+The `EventProcessor` interface allows you to monitor Compose operations in real-time by receiving events about changes
+applied to Docker resources such as images, containers, volumes, and networks. This is particularly useful for building
+user interfaces, logging systems, or monitoring tools that need to track the progress of Compose operations.
+
+### Understanding EventProcessor
+
+A Compose operation (like `Up`, `Down`, `Build`, etc.) performs a series of changes to Docker resources. The
+`EventProcessor` receives notifications about these changes through three key methods:
+
+- **`Start(ctx, operation)`** - Called when a Compose operation begins (e.g., "up")
+- **`On(events...)`** - Called with progress events for individual resource changes (e.g., container starting, image
+  being pulled)
+- **`Done(operation, success)`** - Called when the operation completes, indicating success or failure
+
+Each event contains information about the resource being modified, its current status, and progress indicators when
+applicable (such as download progress for image pulls).
+
+### Event Status Types
+
+Events report resource changes with the following status types:
+
+- **Working** - Operation is in progress (e.g., creating, starting, pulling)
+- **Done** - Operation completed successfully
+- **Warning** - Operation completed with warnings
+- **Error** - Operation failed
+
+Common status text values include: `Creating`, `Created`, `Starting`, `Started`, `Running`, `Stopping`, `Stopped`,
+`Removing`, `Removed`, `Building`, `Built`, `Pulling`, `Pulled`, and more.
+
+### Built-in EventProcessor Implementations
+
+The SDK provides three ready-to-use `EventProcessor` implementations:
+
+- **`progress.NewTTYWriter(io.Writer)`** - Renders an interactive terminal UI with progress bars and task lists
+  (similar to the Docker Compose CLI output)
+- **`progress.NewPlainWriter(io.Writer)`** - Outputs simple text-based progress messages suitable for non-interactive
+  environments or log files
+- **`progress.NewJSONWriter()`** - Render events as JSON objects
+- **`progress.NewQuietWriter()`** - (default) Silently processes events without producing any output
+
+Using `EventProcessor`, a custom UI can be plugged into docker/compose
+