quadlet install: multiple quadlets from single file should share app

Quadlets installed from `.quadlet` file now belongs to a single
application, anyone file removed from this application removes all the
other files as well.

Assited by: claude-4-sonnet

Signed-off-by: flouthoc <flouthoc.git@gmail.com>

Author: flouthoc

docs/source/markdown/podman-quadlet-install.1.md

@@ -16,9 +16,9 @@ This command allows you to:
 
     * Specify a directory containing multiple Quadlet files and other non-Quadlet files for installation ( example a config file for a quadlet container ).
 
-    * Install multiple Quadlets from a single file with `.quadlets` extension where each Quadlet is separated by a `---` delimiter. When using multiple quadlets in a single file, each quadlet section must include a `# FileName=<name>` comment to specify the name for that quadlet.
+    * Install multiple Quadlets from a single file with the `.quadlets` extension, where each Quadlet is separated by a `---` delimiter. When using multiple quadlets in a single `.quadlets` file, each quadlet section must include a `# FileName=<name>` comment to specify the name for that quadlet, extension of `FileName` is not required as it will be generated by parser internally.
 
-Note: If a quadlet is part of an application, removing that specific quadlet will remove the entire application. When a quadlet is installed from a directory, all files installed from that directory—including both quadlet and non-quadlet files—are considered part of a single application.
+Note: If a quadlet is part of an application, removing that specific quadlet will remove the entire application. When a quadlet is installed from a directory, all files installed from that directory—including both quadlet and non-quadlet files—are considered part of a single application. Similarly, when multiple quadlets are installed from a single `.quadlets` file, they are all considered part of the same application.
 
 Note: In case user wants to install Quadlet application then first path should be the path to application directory.
 
@@ -69,15 +69,11 @@ $ cat webapp.quadlets
 Image=nginx:latest
 ContainerName=web-server
 PublishPort=8080:80
-
 ---
-
 # FileName=app-storage
 [Volume]
 Label=app=webapp
-
 ---
-
 # FileName=app-network
 [Network]
 Subnet=10.0.0.0/24

pkg/domain/infra/abi/quadlet.go

@@ -164,7 +164,15 @@ func (ic *ContainerEngine) QuadletInstall(ctx context.Context, pathsOrURLs []str
 	for _, toInstall := range paths {
 		validateQuadletFile := false
 		if assetFile == "" {
-			assetFile = "." + filepath.Base(toInstall) + ".asset"
+			// Check if this is a .quadlets file - if so, treat as an app
+			ext := filepath.Ext(toInstall)
+			if ext == ".quadlets" {
+				// For .quadlets files, use .app extension to group all quadlets as one application
+				baseName := strings.TrimSuffix(filepath.Base(toInstall), filepath.Ext(toInstall))
+				assetFile = "." + baseName + ".app"
+			} else {
+				assetFile = "." + filepath.Base(toInstall) + ".asset"
+			}
 			validateQuadletFile = true
 		}
 		switch {
@@ -212,36 +220,19 @@ func (ic *ContainerEngine) QuadletInstall(ctx context.Context, pathsOrURLs []str
 
 			// Check if this file has a supported extension or is a .quadlets file
 			hasValidExt := systemdquadlet.IsExtSupported(toInstall)
-			ext := strings.ToLower(filepath.Ext(toInstall))
-			isQuadletsFile := ext == ".quadlets"
-
-			// Only check for multi-quadlet content if it's a .quadlets file
-			var isMulti bool
-			if isQuadletsFile {
-				var err error
-				isMulti, err = isMultiQuadletFile(toInstall)
-				if err != nil {
-					installReport.QuadletErrors[toInstall] = fmt.Errorf("unable to check if file is multi-quadlet: %w", err)
-					continue
-				}
-				// For .quadlets files, always treat as multi-quadlet (even single quadlets)
-				isMulti = true
-			}
+			isQuadletsFile := filepath.Ext(toInstall) == ".quadlets"
 
 			// Handle files with unsupported extensions that are not .quadlets files
 			if !hasValidExt && !isQuadletsFile {
 				// If we're installing as part of an app (assetFile is set), allow non-quadlet files as assets
-				if assetFile != "" {
-					// This is part of an app installation, allow non-quadlet files as assets
-					// Don't validate as quadlet file (validateQuadletFile will be false)
-				} else {
+				if assetFile == "" {
 					// Standalone files with unsupported extensions are not allowed
 					installReport.QuadletErrors[toInstall] = fmt.Errorf("%q is not a supported Quadlet file type", filepath.Ext(toInstall))
 					continue
 				}
 			}
 
-			if isMulti {
+			if isQuadletsFile {
 				// Parse the multi-quadlet file
 				quadlets, err := parseMultiQuadletFile(toInstall)
 				if err != nil {
@@ -257,11 +248,11 @@ func (ic *ContainerEngine) QuadletInstall(ctx context.Context, pathsOrURLs []str
 						installReport.QuadletErrors[toInstall] = fmt.Errorf("unable to create temporary file for quadlet section %s: %w", quadlet.name, err)
 						continue
 					}
-
+					defer os.Remove(tmpFile.Name())
 					// Write the quadlet content to the temporary file
 					_, err = tmpFile.WriteString(quadlet.content)
+					tmpFile.Close()
 					if err != nil {
-						tmpFile.Close()
 						os.Remove(tmpFile.Name())
 						installReport.QuadletErrors[toInstall] = fmt.Errorf("unable to write quadlet section %s to temporary file: %w", quadlet.name, err)
 						continue
@@ -385,6 +376,14 @@ func (ic *ContainerEngine) installQuadlet(_ context.Context, path, destName, ins
 		if err != nil {
 			return "", fmt.Errorf("error while writing non-quadlet filename: %w", err)
 		}
+	} else if strings.HasSuffix(assetFile, ".app") {
+		// For quadlet files that are part of an application (indicated by .app extension),
+		// also write the quadlet filename to the .app file for proper application tracking
+		quadletName := filepath.Base(finalPath)
+		err := appendStringToFile(filepath.Join(installDir, assetFile), quadletName)
+		if err != nil {
+			return "", fmt.Errorf("error while writing quadlet filename to app file: %w", err)
+		}
 	}
 	return finalPath, nil
 }
@@ -430,11 +429,8 @@ func parseMultiQuadletFile(filePath string) ([]quadletSection, error) {
 				currentSection.Reset()
 			}
 		} else {
-			// Add line to current section
-			if currentSection.Len() > 0 {
-				currentSection.WriteString("\n")
-			}
 			currentSection.WriteString(line)
+			currentSection.WriteString("\n")
 		}
 	}
 
@@ -529,45 +525,15 @@ func detectQuadletType(content string) (string, error) {
 		line = strings.TrimSpace(line)
 		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
 			sectionName := strings.ToLower(strings.Trim(line, "[]"))
-			switch sectionName {
-			case "container":
-				return ".container", nil
-			case "volume":
-				return ".volume", nil
-			case "network":
-				return ".network", nil
-			case "kube":
-				return ".kube", nil
-			case "image":
-				return ".image", nil
-			case "build":
-				return ".build", nil
-			case "pod":
-				return ".pod", nil
+			expected := "." + sectionName
+			if systemdquadlet.IsExtSupported("a" + expected) {
+				return expected, nil
 			}
 		}
 	}
 	return "", fmt.Errorf("no recognized quadlet section found (expected [Container], [Volume], [Network], [Kube], [Image], [Build], or [Pod])")
 }
 
-// isMultiQuadletFile checks if a file contains multiple quadlets by looking for "---" delimiter
-// The delimiter must be on its own line (possibly with whitespace)
-func isMultiQuadletFile(filePath string) (bool, error) {
-	content, err := os.ReadFile(filePath)
-	if err != nil {
-		return false, err
-	}
-
-	lines := strings.Split(string(content), "\n")
-	for _, line := range lines {
-		trimmed := strings.TrimSpace(line)
-		if trimmed == "---" {
-			return true, nil
-		}
-	}
-	return false, nil
-}
-
 // buildAppMap scans the given directory for files that start with '.'
 // and end with '.app', reads their contents (one filename per line), and
 // returns a map where each filename maps to the .app file that contains it.