add agent data directory handling

beszel/internal/agent/data_dir.go

@@ -0,0 +1,122 @@
+package agent
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+// getDataDir returns the path to the data directory for the agent and an error
+// if the directory is not valid. Pass an empty string to attempt to find the
+// optimal data directory.
+func getDataDir(dataDir string) (string, error) {
+	if dataDir == "" {
+		dataDir, _ = GetEnv("DATA_DIR")
+	}
+
+	if dataDir != "" {
+		return testDataDirs([]string{dataDir})
+	}
+
+	var dirsToTry []string
+
+	if runtime.GOOS == "windows" {
+		dirsToTry = []string{
+			filepath.Join(os.Getenv("APPDATA"), "beszel-agent"),
+			filepath.Join(os.Getenv("LOCALAPPDATA"), "beszel-agent"),
+		}
+	} else {
+		homeDir, err := os.UserHomeDir()
+		if err != nil {
+			return "", err
+		}
+		dirsToTry = []string{
+			"/var/lib/beszel-agent",
+			filepath.Join(homeDir, ".config", "beszel"),
+		}
+	}
+	return testDataDirs(dirsToTry)
+}
+
+func testDataDirs(paths []string) (string, error) {
+	// first check if the directory exists and is writable
+	for _, path := range paths {
+		if valid, _ := isValidDataDir(path, false); valid {
+			return path, nil
+		}
+	}
+	// if the directory doesn't exist, try to create it
+	for _, path := range paths {
+		exists, _ := directoryExists(path)
+		if exists {
+			continue
+		}
+
+		if err := os.MkdirAll(path, 0755); err != nil {
+			continue
+		}
+
+		// Verify the created directory is actually writable
+		writable, _ := directoryIsWritable(path)
+		if !writable {
+			continue
+		}
+
+		return path, nil
+	}
+
+	return "", errors.New("data directory not found")
+}
+
+func isValidDataDir(path string, createIfNotExists bool) (bool, error) {
+	exists, err := directoryExists(path)
+	if err != nil {
+		return false, err
+	}
+
+	if !exists {
+		if !createIfNotExists {
+			return false, nil
+		}
+		if err = os.MkdirAll(path, 0755); err != nil {
+			return false, err
+		}
+	}
+
+	// Always check if the directory is writable
+	writable, err := directoryIsWritable(path)
+	if err != nil {
+		return false, err
+	}
+	return writable, nil
+}
+
+// directoryExists checks if a directory exists
+func directoryExists(path string) (bool, error) {
+	// Check if directory exists
+	stat, err := os.Stat(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return false, nil
+		}
+		return false, err
+	}
+	if !stat.IsDir() {
+		return false, fmt.Errorf("%s is not a directory", path)
+	}
+	return true, nil
+}
+
+// directoryIsWritable tests if a directory is writable by creating and removing a temporary file
+func directoryIsWritable(path string) (bool, error) {
+	testFile := filepath.Join(path, ".write-test")
+	file, err := os.Create(testFile)
+	if err != nil {
+		return false, err
+	}
+	defer file.Close()
+	defer os.Remove(testFile)
+	return true, nil
+}