feat: implement 'caddy deploy' command to deploy global service using caddy:latest image

internal/cli/client/caddy.go

@@ -1,10 +1,43 @@
 package client
 
 import (
-	"context"
-	"errors"
+	"uncloud/internal/api"
 )
 
-func (cli *Client) DeployCaddy(ctx context.Context, image string) error {
-	return errors.New("not implemented")
+const CaddyServiceName = "caddy"
+
+// NewCaddyDeployment creates a new deployment for a Caddy reverse proxy service.
+// The service is deployed in global mode to all machines in the cluster. If the image is not provided, the latest
+// version of the official Caddy Docker image is used.
+func (cli *Client) NewCaddyDeployment(image string) (*Deployment, error) {
+	if image == "" {
+		// TODO: fetch the latest version tag from the Docker Hub registry.
+		image = "caddy:latest"
+	}
+
+	spec := api.ServiceSpec{
+		Container: api.ContainerSpec{
+			Command: []string{"caddy", "run", "-c", "/config/caddy.json", "--watch"},
+			Image:   image,
+			Volumes: []string{"/var/lib/uncloud/caddy:/config"},
+		},
+		Mode: api.ServiceModeGlobal,
+		Name: CaddyServiceName,
+		Ports: []api.PortSpec{
+			{
+				PublishedPort: 80,
+				ContainerPort: 80,
+				Protocol:      api.ProtocolTCP,
+				Mode:          api.PortModeHost,
+			},
+			{
+				PublishedPort: 443,
+				ContainerPort: 443,
+				Protocol:      api.ProtocolTCP,
+				Mode:          api.PortModeHost,
+			},
+		},
+	}
+
+	return cli.NewDeployment(spec, &RollingStrategy{})
 }