resolve symbolic links when loading develop.watch.path

Signed-off-by: Joana Hrotko <joana.hrotko@docker.com>

paths/resolve.go

@@ -38,7 +38,7 @@ func ResolveRelativePaths(project map[string]any, base string, remotes []RemoteR
 		"services.*.build.additional_contexts.*": r.absContextPath,
 		"services.*.env_file.*.path":             r.absPath,
 		"services.*.extends.file":                r.absExtendsPath,
-		"services.*.develop.watch.*.path":        r.absPath,
+		"services.*.develop.watch.*.path":        r.absSymbolicLink,
 		"services.*.volumes.*":                   r.absVolumeMount,
 		"configs.*.file":                         r.maybeUnixPath,
 		"secrets.*.file":                         r.maybeUnixPath,

paths/unix.go

@@ -19,6 +19,8 @@ package paths
 import (
 	"path"
 	"path/filepath"
+
+	"github.com/compose-spec/compose-go/v2/utils"
 )
 
 func (r *relativePathsResolver) maybeUnixPath(a any) (any, error) {
@@ -38,3 +40,15 @@ func (r *relativePathsResolver) maybeUnixPath(a any) (any, error) {
 	}
 	return p, nil
 }
+
+func (r *relativePathsResolver) absSymbolicLink(value any) (any, error) {
+	abs, err := r.absPath(value)
+	if err != nil {
+		return nil, err
+	}
+	str, ok := abs.(string)
+	if !ok {
+		return abs, nil
+	}
+	return utils.ResolveSymbolicLink(str)
+}

utils/pathutils.go

@@ -0,0 +1,92 @@
+/*
+   Copyright 2020 The Compose Specification Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package utils
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// ResolveSymbolicLink converts the section of an absolute path if it is a
+// symbolic link
+//
+// Parameters:
+//   - path: an absolute path
+//
+// Returns:
+//   - converted path if it has a symbolic link or the same path if there is
+//     no symbolic link
+func ResolveSymbolicLink(path string) (string, error) {
+	sym, part, err := getSymbolinkLink(path)
+	if err != nil {
+		return "", err
+	}
+	if sym == "" && part == "" {
+		// no symbolic link detected
+		return path, nil
+	}
+	return strings.Replace(path, part, sym, 1), nil
+
+}
+
+// getSymbolinkLink parses all parts of the path and returns the
+// the symbolic link part as well as the correspondent original part
+// Parameters:
+//   - path: an absolute path
+//
+// Returns:
+//   - string section of the path that is a symbolic link
+//   - string correspondent path section of the symbolic link
+//   - An error
+func getSymbolinkLink(path string) (string, string, error) {
+	parts := strings.Split(path, string(os.PathSeparator))
+
+	// Reconstruct the path step by step, checking each component
+	var currentPath string
+	if filepath.IsAbs(path) {
+		currentPath = string(os.PathSeparator)
+	}
+
+	for _, part := range parts {
+		if part == "" {
+			continue
+		}
+		currentPath = filepath.Join(currentPath, part)
+
+		if isSymLink := isSymbolicLink(currentPath); isSymLink {
+			// return symbolic link, and correspondent part
+			target, err := filepath.EvalSymlinks(currentPath)
+			if err != nil {
+				return "", "", err
+			}
+			return target, currentPath, nil
+		}
+	}
+	return "", "", nil // no symbolic link
+}
+
+// isSymbolicLink validates if the path is a symbolic link
+func isSymbolicLink(path string) bool {
+	info, err := os.Lstat(path)
+	if err != nil {
+		return false
+	}
+
+	// Check if the file mode indicates a symbolic link
+	return info.Mode()&os.ModeSymlink != 0
+}