flutter_logs #

A file based advanced logging framework for Flutter Apps (Android & iOS).

Overview #

Flutter Logs provides quick & simple file based logging solution. All logs are saved to files in storage path provided. A new log file is created every hour on a new log event. These logs can be filtered and sorted easily. Logs can easily be exported as zip file base on filter type. PLogs also provide functionality to arrange data logs into a predefined directory structure. Custom logs can be used for a specific events based logging within the app. Logs can be saved as encrypted for security purposes.

Flutter logs can work with Logstash by writing JSON delimited logs to log files. The format is based on ELK schema. You can also send logs in real-time to server using MQTT. MQTT configuration can be applied on Logstash to receive & view logs on kibana dashboard.

Read more about flutter_logs usage on this Medium article:

Sending logs from Flutter apps in real-time using ELK stack & MQTT

Features (Android) #

• Logs events in files created separately every hour (24 hours event based)
• Files can be compressed and exported for time and day filters
• Clear Logs easily
• Save & Export Logs to app's directory as zip file
• Custom Log formatting options
• CSV support
• Custom timestamps support
• Custom file data logging support.
• Encryption support added
• Multiple directory structures
• Print logs as String
• Export all or single types of logs
• ELK Stack Supported See more about it here.
• MQTT Support (SSL)
• Backpressure support for high-volume logging scenarios
• Redaction & Masking for sensitive data (PII protection)
• Search & Filter logs by keywords

Features (iOS) #

Note: Work is in progress. More features will be added soon.

• Logs events in files
• Files can be compressed and exported
• Clear Logs easily
• Save & Export Logs to app's directory as zip file
• Print logs as String

Install #

In your pubspec.yaml

dependencies:
    flutter_logs: ^2.2.2

import 'package:flutter_logs/flutter_logs.dart';

Setting Up #

Initialization

In your main.dart file add like this:

   
   import 'package:flutter_logs/flutter_logs.dart';

   Future<void> main() async {
     WidgetsFlutterBinding.ensureInitialized();

     //Initialize Logging
     await FlutterLogs.initLogs(
     logLevelsEnabled: [
       LogLevel.INFO,
       LogLevel.WARNING,
       LogLevel.ERROR,
       LogLevel.SEVERE
     ],
     timeStampFormat: TimeStampFormat.TIME_FORMAT_READABLE,
     directoryStructure: DirectoryStructure.FOR_DATE,
     logTypesEnabled: ["device","network","errors"],
     logFileExtension: LogFileExtension.LOG,
     logsWriteDirectoryName: "MyLogs",
     logsExportDirectoryName: "MyLogs/Exported",
     debugFileOperations: true,
     isDebuggable: true,
     logsRetentionPeriodInDays = 14,
     zipsRetentionPeriodInDays = 3,
     autoDeleteZipOnExport = false,
     autoClearLogs = true,
             enabled: true);

     runApp(MyApp());
   }

How to log data? #

You have 2 choices for logging:

Hourly Logs #

Hourly logs are automatically generated once this line is called. These logs are sorted and named according to current time (24h format) on device e.g. 0110202013.log

FlutterLogs.logThis(
        tag: 'MyApp',
        subTag: 'logData',
        logMessage:
            'This is a log message: ${DateTime.now().millisecondsSinceEpoch}',
        level: LogLevel.INFO);

Or simply call this:

    FlutterLogs.logInfo("TAG", "subTag", "My Log Message");
    
    FlutterLogs.logWarn("TAG", "subTag", "My Log Message");
    
    FlutterLogs.logError("TAG", "subTag", "My Log Message");
    
    FlutterLogs.logErrorTrace("TAG", "subTag", "My Log Message", Error());

This will create a new file in storage directory according to time on device. For a single date, all logs will be present in a single directory.

Custom File Logs #

If you want to log data into a specific file for some events, you can do this in 2 steps:

These logs will be kept in a seperate file.

Step 1:

[IMPORTANT] Define log file name in logs configuration, logger needs the name to find the file on storage, otherwise no data will be logged.

Here 3 files of logs are defined, logger will use these file name as keys to write data in them.

    await FlutterLogs.initLogs(
        logTypesEnabled: ["Locations","Jobs","API"]);

Step 2:

Log data to file. You can choose to either append to file or overwrite to complete file.

    FlutterLogs.logToFile(
        logFileName: "Locations",
        overwrite: false,
        logMessage:
            "{0.0,0.0}");

Where are my logs stored? #

Your logs can be found in the path of your app's directory in storage:

Android:

--> Android/data/[YOUR_APP_PACKAGE]/files/[YOUR_LOGS_FOLDER_NAME]/Logs/

iOS:

--> [YOUR_APP_CONTAINER]/AppData/Library/Application Support/Logs/

Export/Print Logs #

You can export logs to output path sepcified in logs configuration:

    await FlutterLogs.initLogs(
        logsExportDirectoryName: "MyLogs/Exported");

To export logs call this:

    FlutterLogs.exportLogs(
        exportType: ExportType.ALL);

    FlutterLogs.printLogs(
        exportType: ExportType.ALL);

To export custom file logs:

 FlutterLogs.exportFileLogForName(
        logFileName: "Locations");

 FlutterLogs.printFileLogForName(
        logFileName: "Locations");

Listen to export/print results: #

    import 'dart:async';
    import 'dart:io';
    import 'package:flutter_logs/flutter_logs.dart';
    import 'package:path_provider/path_provider.dart';

    FlutterLogs.channel.setMethodCallHandler((call) async {
        if (call.method == 'logsExported') {
          var zipName = "${call.arguments.toString()}";

            Directory externalDirectory;

            if (Platform.isIOS) {
              externalDirectory = await getApplicationDocumentsDirectory();
            } else {
              externalDirectory = await getExternalStorageDirectory();
            }

            FlutterLogs.logInfo(TAG, "found", 'External Storage:$externalDirectory');

          File file = File("${externalDirectory.path}/$zipName");

          FlutterLogs.logInfo(
              TAG, "path", 'Path: \n${file.path.toString()}');

          if (file.existsSync()) {
            FlutterLogs.logInfo(
                TAG, "existsSync", 'Logs found and ready to export!');
          } else {
            FlutterLogs.logError(
                TAG, "existsSync", "File not found in storage.");
          }
          
        } else if (call.method == 'logsPrinted') {
          //TODO Get results of logs print here
        }
      });

Exports logs manually #

Include dependency:

         flutter_archive: ^6.0.3

       Directory? externalDirectory;
      
       if (Platform.isIOS) {
           externalDirectory = await getApplicationDocumentsDirectory();
       } else {
           externalDirectory = await getExternalStorageDirectory();
       }

      File file = File("${externalDirectory!.path}/$_logsDirectory");
      
      final zipFile = File("${externalDirectory.path}/logs.zip");
      try {
           await ZipFile.createFromDirectory(
           sourceDir: Directory(file.path),
           zipFile: zipFile,
           includeBaseDirectory: true);
      } catch (e) {
           print(e);
      }

      logInfo(_tag, "uploadFile", 'Storage:${file.path}, Zip: ${zipFile.path}');
}

Clear Logs #

 FlutterLogs.clearLogs();

Errors/Exception Logs #

Printing exception logs:

      try {
          var i = 100 ~/ 0;
          print("$i");
      } catch (e) {
          FlutterLogs.logThis(
              tag: 'MyApp',
              subTag: 'Caught an exception.',
              logMessage: 'Caught an exception!',
              exception: e,
              level: LogLevel.ERROR);
      }

Printing error logs:

      try {
          var i = null;
          print(i * 10);
      } catch (e) {
          FlutterLogs.logThis(
              tag: 'MyApp',
              subTag: 'Caught an error.',
              logMessage: 'Caught an exception!',
              error: e,
              level: LogLevel.ERROR);
      }

Backpressure Support #

Backpressure helps manage high-volume logging scenarios by limiting queue size and setting quotas per log level to prevent memory issues and ensure critical logs are prioritized.

    await FlutterLogs.initLogs(
        // ... other configurations ...
        backpressureConfig: BackpressureConfig(
          queueCapacity: 500,        // Max logs in queue before dropping
          warnQueueCapacity: 400,    // Warn when queue reaches this size
          perLevelQuotas: {
            LogLevel.INFO: 100,      // Max 100 INFO logs per window
            LogLevel.WARNING: 50,    // Max 50 WARNING logs per window
            LogLevel.ERROR: 200,     // Prioritize error logs
            LogLevel.SEVERE: 200,    // Prioritize severe logs
          },
          quotaWindowMillis: 60000,  // 1 minute window for quotas
        ),
    );

Redaction & Masking (PII Protection) #

Automatically mask sensitive data like emails, phone numbers, credit cards, and custom patterns in your logs for privacy and security compliance.

Built-in Patterns

    await FlutterLogs.initLogs(
        // ... other configurations ...
        redactionConfig: RedactionConfig(
          enableBuiltInPatterns: {
            BuiltInPattern.EMAIL,        // Masks email addresses
            BuiltInPattern.PHONE_NUMBER, // Masks phone numbers
            BuiltInPattern.CREDIT_CARD,  // Masks credit card numbers
            BuiltInPattern.JWT_TOKEN,    // Masks JWT tokens
            BuiltInPattern.IP_ADDRESS,   // Masks IP addresses
          },
          defaultMaskType: MaskType.FULL_MASK,
        ),
    );

Custom Redaction Rules

You can define custom rules with regex patterns:

    await FlutterLogs.initLogs(
        // ... other configurations ...
        redactionConfig: RedactionConfig(
          enableBuiltInPatterns: {BuiltInPattern.EMAIL},
          customRules: [
            // Mask SSN patterns (XXX-XX-XXXX)
            RedactionRule(
              name: 'SSN',
              patternString: r'\b\d{3}-\d{2}-\d{4}\b',
              maskType: MaskType.FULL_MASK,
            ),
            // Partially mask API keys (show first 4 chars)
            RedactionRule(
              name: 'API_KEY',
              patternString: r'api_key[=:]\s*([A-Za-z0-9]{20,})',
              maskType: MaskType.PARTIAL,
            ),
            // Hash user IDs for tracking without exposing actual IDs
            RedactionRule(
              name: 'USER_ID',
              patternString: r'user_id[=:]\s*(\d+)',
              maskType: MaskType.HASH,
            ),
            // Custom replacement text
            RedactionRule(
              name: 'PASSWORD',
              patternString: r'password[=:]\s*\S+',
              maskType: MaskType.FULL_MASK,
              replacement: 'password=[REDACTED]',
            ),
          ],
          defaultMaskType: MaskType.FULL_MASK,
        ),
    );

Mask Types

Search & Filter Logs #

Search through all log files for specific keywords and export or print only matching lines.

Export Filtered Logs

    FlutterLogs.exportFilteredLogs(
      keywords: ['ERROR', 'login', 'failed'],
      filterType: FilterType.OR,    // Match ANY keyword (use AND to match ALL)
      exportType: ExportType.ALL,
      ignoreCase: true,
    );

Print Filtered Logs

    FlutterLogs.printFilteredLogs(
      keywords: ['network', 'timeout'],
      filterType: FilterType.AND,   // Match ALL keywords
      exportType: ExportType.TODAY,
      ignoreCase: true,
    );

Filter Types

ELK Elastic Stack Schema Support

Send additional Meta info for better filtering at LogStash dashboard. With this setting, logs will be logged as JSON-delemited.

    await FlutterLogs.setMetaInfo(
      appId: "flutter_logs_example",
      appName: "Flutter Logs Demo",
      appVersion: "1.0",
      language: "en-US",
      deviceId: "00012",
      environmentId: "7865",
      environmentName: "dev",
      organizationId: "5767",
      userId: "883023-2832-2323",
      userName: "umair13adil",
      userEmail: "m.umair.adil@gmail.com",
      deviceSerial: "YJBKKSNKDNK676",
      deviceBrand: "LG",
      deviceName: "LG-Y08",
      deviceManufacturer: "LG",
      deviceModel: "989892BBN",
      deviceSdkInt: "26",
      latitude: "0.0",
      longitude: "0.0",
      labels: "",
    );

Output of logs will be like this:

{
  "user": {
    "user.email": "m.umair.adil@gmail.com",
    "user.full_name": "umair",
    "user.id": "17282738",
    "user.hash": "1",
    "user.name": "Umair"
  },
  "message": "{OkHttpClient}  {X-XSS-Protection: 1; mode=block} [30 June 2020 04:15:16 PM]",
  "@version": "1",
  "log.logger": "PLogger",
  "host": {
    "host.type": "Android",
    "host.name": "LG",
    "host.architecture": "LG 23",
    "host.hostname": "8000",
    "host.id": "LG",
    "host.ip": "0.0.0.0",
    "host.mac": ""
  },
  "labels": "{}",
  "app": {
    "app.language": "en-US",
    "app.id": "com.example.develop",
    "app.name": "Flutter Dev",
    "app.version": "0.0.108"
  },
  "process.thread.name": "DATA_LOG",
  "organization": {
    "organization.name": "debug",
    "organization.id": "BlackBox"
  },
  "geo": {
    "geo.location": "{ \"lon\": 0.0, \"lat\": 0.0 }"
  },
  "service.name": "Network",
  "@timestamp": "2020-06-30T16:27:36.894Z",
  "topic": "com.flutter.elk.logs",
  "log.level": "INFO"
}

Enable MQTT Feature

Note: PLogger currently supports SSL connection for MQTT.

Step 1:

Add certificate in your assets directory.

Step 2:

Add following line in your pubspec file.

flutter:
  assets:
     - m2mqtt_ca.crt

Step 3:

Add following block for initializing MQTT logging.

    await FlutterLogs.initMQTT(
        topic: "YOUR_TOPIC",
        brokerUrl: "", //Add URL without schema
        certificate: "m2mqtt_ca.crt",
        port: "8883");

That's it, MQTT setup is done. If only MQTT feature is required then set this flag to false to stop writing logs to storage directory:

    await FlutterLogs.initMQTT(
        writeLogsToLocalStorage: false);

Native Libraries #

• For Android: RxLogs
• For iOS ZIPFoundation

For more details about RxLogs visit this Wiki

Author #

Flutter Logs plugin is developed by Umair Adil. You can email me at m.umair.adil@gmail.com for any queries.

Support #

Buy a coffe to Umair Adil, creator of this plugin.