fix: improve nil handling of sql/folder checks

checks/folder.go

@@ -89,34 +89,43 @@ func checkLocalFolder(ctx *context.Context, check v1.FolderCheck) pkg.Results {
 	var results pkg.Results
 	results = append(results, result)
 	folders, err := getLocalFolderCheck(check.Path, check.Filter)
+	result.AddDetails(folders)
+
 	if err != nil {
 		return results.ErrorMessage(err)
 	}
-	result.AddDetails(folders)
 
 	if test := folders.Test(check.FolderTest); test != "" {
 		return results.Failf(test)
 	}
 	return results
 }
 
-func getLocalFolderCheck(path string, filter v1.FolderFilter) (*FolderCheck, error) {
+func getLocalFolderCheck(path string, filter v1.FolderFilter) (FolderCheck, error) {
 	result := FolderCheck{}
 	_filter, err := filter.New()
 	if err != nil {
-		return nil, err
+		return result, err
+	}
+	if dir, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			return result, nil
+		}
+		return result, err
+	} else if !dir.IsDir() {
+		return result, fmt.Errorf("%s is not a directory", path)
 	}
 	files, err := os.ReadDir(path)
 	if err != nil {
-		return nil, err
+		return result, err
 	}
 	if len(files) == 0 {
 		// directory is empty. returning duration of directory
 		info, err := os.Stat(path)
 		if err != nil {
-			return nil, err
+			return result, err
 		}
-		return &FolderCheck{
+		return FolderCheck{
 			Oldest:        newFile(info),
 			Newest:        newFile(info),
 			AvailableSize: SizeNotSupported,
@@ -126,15 +135,15 @@ func getLocalFolderCheck(path string, filter v1.FolderFilter) (*FolderCheck, err
 	for _, file := range files {
 		info, err := file.Info()
 		if err != nil {
-			return nil, err
+			return result, err
 		}
 		if file.IsDir() || !_filter.Filter(info) {
 			continue
 		}
 
 		result.Append(info)
 	}
-	return &result, err
+	return result, err
 }
 
 func getGenericFolderCheck(fs Filesystem, dir string, filter v1.FolderFilter) (*FolderCheck, error) {

checks/folder_check.go

@@ -21,7 +21,7 @@ type FolderCheck struct {
 	MaxSize       *File  `json:"largest,omitempty"`
 	TotalSize     int64  `json:"size,omitempty"`
 	AvailableSize int64  `json:"availableSize,omitempty"`
-	Files         []File `json:"files,omitempty"`
+	Files         []File `json:"files"`
 }
 
 type File struct {

checks/sql.go

@@ -19,7 +19,7 @@ type SQLChecker interface {
 }
 
 type SQLDetails struct {
-	Rows  []map[string]interface{} `json:"rows,omitempty"`
+	Rows  []map[string]interface{} `json:"rows"`
 	Count int                      `json:"count,omitempty"`
 }
 
@@ -28,23 +28,24 @@ type SQLDetails struct {
 // Connects to a db using the specified `driver` and `connectionstring`
 // Performs the test query given in `query`.
 // Gives the single row test query result as result.
-func querySQL(driver string, connection string, query string) (*SQLDetails, error) {
+func querySQL(driver string, connection string, query string) (SQLDetails, error) {
+	result := SQLDetails{}
 	db, err := sql.Open(driver, connection)
 	if err != nil {
-		return nil, fmt.Errorf("failed to connect to db: %w", err)
+		return result, fmt.Errorf("failed to connect to db: %w", err)
 	}
 	defer db.Close()
 
 	rows, err := db.Query(query)
-	result := SQLDetails{}
+
 	if err != nil || rows.Err() != nil {
-		return nil, fmt.Errorf("failed to query db: %w", err)
+		return result, fmt.Errorf("failed to query db: %w", err)
 	}
 	defer rows.Close()
 
 	columns, err := rows.Columns()
 	if err != nil {
-		return nil, fmt.Errorf("failed to get columns: %w", err)
+		return result, fmt.Errorf("failed to get columns: %w", err)
 	}
 
 	for rows.Next() {
@@ -54,7 +55,7 @@ func querySQL(driver string, connection string, query string) (*SQLDetails, erro
 			rowValues[i] = &s
 		}
 		if err := rows.Scan(rowValues...); err != nil {
-			return nil, err
+			return result, err
 		}
 
 		var row = make(map[string]interface{})
@@ -71,7 +72,7 @@ func querySQL(driver string, connection string, query string) (*SQLDetails, erro
 	}
 
 	result.Count = len(result.Rows)
-	return &result, nil
+	return result, nil
 }
 
 // CheckSQL : Attempts to connect to a DB using the specified
@@ -110,11 +111,12 @@ func CheckSQL(ctx *context.Context, checker SQLChecker) pkg.Results { // nolint:
 	}
 
 	details, err := querySQL(checker.GetDriver(), connection.URL, query)
+	result.AddDetails(details)
+
 	if err != nil {
 		return results.ErrorMessage(err)
 	}
 
-	result.AddDetails(details)
 	if details.Count < check.Result {
 		return results.Failf("Query returned %d rows, expected %d", details.Count, check.Result)
 	}

fixtures/datasources/folder_pass.yaml

@@ -3,7 +3,7 @@ kind: Canary
 metadata:
   name: folder-pass
 spec:
-  interval: 10
+  interval: 300
   folder:
     - path: /etc/
       name: Check for updated /etc files
@@ -32,3 +32,15 @@ spec:
         - name: new_files
           value: results.?files.orValue([]).size()
           type: counter
+---
+apiVersion: canaries.flanksource.com/v1
+kind: Canary
+metadata:
+  name: folder-pass-empty
+spec:
+  interval: 300
+  folder:
+    - name: folder-nil-handling
+      path: /some/folder/that/does/not/exist
+      test:
+        expr: results.files.size() == 0