chore: handle x-caddy: path/to/Caddyfile to read Caddy config in compose from file

pkg/client/compose/caddy.go

@@ -2,7 +2,11 @@ package compose
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
 
+	"github.com/compose-spec/compose-go/v2/types"
 	"github.com/mitchellh/mapstructure"
 )
 
@@ -41,3 +45,48 @@ func (c *Caddy) DecodeMapstructure(value any) error {
 	}
 	return nil
 }
+
+// isCaddyfilePath determines if a string is likely a file path rather than inline Caddyfile config.
+func isCaddyfilePath(s string) bool {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return false
+	}
+
+	// For simplicity, multi-line string is considered an inline Caddyfile content.
+	return !strings.Contains(s, "\n")
+}
+
+// transformServicesCaddyExtension processes Caddy extensions to load configs from files if needed.
+func transformServicesCaddyExtension(project *types.Project) (*types.Project, error) {
+	return project.WithServicesTransform(func(name string, service types.ServiceConfig) (types.ServiceConfig, error) {
+		ext, ok := service.Extensions[CaddyExtensionKey]
+		if !ok {
+			return service, nil
+		}
+
+		caddy, ok := ext.(Caddy)
+		if !ok {
+			return service, nil
+		}
+
+		// Load the Caddyfile config from file if it's a path and replace the path with its content.
+		if isCaddyfilePath(caddy.Config) {
+			configPath := caddy.Config
+			if !filepath.IsAbs(configPath) {
+				configPath = filepath.Join(project.WorkingDir, configPath)
+			}
+
+			content, err := os.ReadFile(configPath)
+			if err != nil {
+				return service, fmt.Errorf("read Caddy config (Caddyfile) from file '%s' for service '%s': %w",
+					caddy.Config, name, err)
+			}
+
+			caddy.Config = string(content)
+			service.Extensions[CaddyExtensionKey] = caddy
+		}
+
+		return service, nil
+	})
+}