aws_cloudwatch

A package that sends logs to AWS CloudWatch.

Currently only logging is supported

This package is still under development

The repository can be found here

If you have feedback or have a use case that isn't covered feel free to contact me.

Getting Started

To get started add aws_cloudwatch: ^[CURRENT_VERION], to your pubspec.yaml

Then add import 'package:aws_cloudwatch/aws_cloudwatch.dart'; to the top of your file.

Create a CloudWatch instance by calling

CloudWatch cloudWatch = new CloudWatch(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, REGION, 
    groupName:GROUP_NAME, streamName:STREAM NAME);

Finally, send a log by calling cloudWatch.log('STRING TO LOG');

Examples

Example - Quick Start

This is the quick start file. It is also location in example/aws_cloudwatch.dart

import 'package:aws_cloudwatch/aws_cloudwatch.dart';
import 'package:intl/intl.dart';

/// QUICK START LOGGING FILE
///
/// PLEASE FILL OUT THE FOLLOWING VARIABLES:

const String _AWS_ACCESS_KEY_ID = 'YOUR_ACCESS_KEY';
const String _AWS_SECRET_ACCESS_KEY = 'YOUR_SECRET_ACCESS_KEY';
const String _Region = 'YOUR_REGION_CODE'; // (us-west-1, us-east-2, etc)
const String _LogGroup = 'DESIRED_LOG_GROUP_NAME';
const String _ErrorGroup = 'DESIRED_ERROR_LOG_GROUP_NAME';

/// END OF VARIABLES

CloudWatchHandler logging = CloudWatchHandler(
  awsAccessKey: _AWS_ACCESS_KEY_ID,
  awsSecretKey: _AWS_SECRET_ACCESS_KEY,
  region: _Region,
  delay: Duration(milliseconds: 200),
);

String logStreamName = '';

// You may want to edit this function to suit your needs
String _getLogStreamName() {
  if (logStreamName == "") {
    logStreamName = DateFormat("yyyy-MM-dd HH-mm-ss").format(
      DateTime.now().toUtc(),
    );
  }
  return logStreamName;
}

void log(String logString, {isError = false}) {
  logging.log(
    msg: logString,
    logGroupName: isError ? _LogGroup : _ErrorGroup,
    logStreamName: _getLogStreamName(),
  );
}

Then just import this file somewhere in your code and call log('HELLO WORLD');. The package will handle creating the log groups and log streams on its own. The way the quick start file is setup, you will end up with one log group for standard logging and another for errors. Both with have the same log stream name. To automatically send logs for all flutter errors see example 3.

Example 1

Here's an example of using aws_cloudwatch to send a CloudWatch PutLogEvent request:

import 'package:aws_cloudwatch/aws_cloudwatch.dart';

// AWS Variables
const String AWS_ACCESS_KEY_ID = 'ExampleKey';
const String AWS_SECRET_ACCESS_KEY = 'ExampleSecret';
const String Region = 'us-west-2';

// Logging Variables
const String logGroupName = 'LogGroupExample';
const String logStreamName = 'LogStreamExample';
CloudWatch cloudWatch = new CloudWatch(AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY,
    Region, groupName: logGroupName, streamName: logStreamName);

void log(String logString) {
  cloudWatch.log(logString);
}

Example 2

Here's an example of using aws_cloudwatch to send a CloudWatch PutLogEvent request with a 200-millisecond delay to avoid rate limiting:

import 'package:aws_cloudwatch/aws_cloudwatch.dart';

// AWS Variables
const String AWS_ACCESS_KEY_ID = 'ExampleKey';
const String AWS_SECRET_ACCESS_KEY = 'ExampleSecret';
const String Region = 'us-west-2';

// Logging Variables
const String logGroupName = 'LogGroupExample';
const String logStreamName = 'LogStreamExample';
CloudWatch cloudWatch = new CloudWatch(AWS_ACCESS_KEY_ID,
  AWS_SECRET_ACCESS_KEY, Region, groupName: logGroupName,
  streamName: logStreamName, delay: Duration(milliseconds: 200));

void log(String logString) {
  cloudWatch.log(logString);
}

By adding a 200-millisecond delay, aws_cloudwatch will send more logs at a time and will be limited to sending api requests at most once every 200 milliseconds. This can reduce the chance of hitting the AWS CloudWatch logging rate limit of 5 requests per second per log stream.

Example 3

Here is an example of how to capture all errors in flutter and send them to CloudWatch. First create this file and name it errorLog.dart

import 'package:aws_request/aws_cloudwatch.dart';
import 'package:intl/intl.dart';

// AWS Variables
const String AWS_ACCESS_KEY_ID = 'ExampleKey';
const String AWS_SECRET_ACCESS_KEY = 'ExampleSecret';
const String Region = 'us-west-2';

// Logging Variables
const String logGroupName = 'LogGroupExample';
const String logGroupNameError = 'LogGroupExample';

CloudWatchHandler logging = CloudWatchHandler(
  awsAccessKey: AWS_ACCESS_KEY_ID,
  awsSecretKey: AWS_SECRET_ACCESS_KEY,
  region: Region,
);

String logStreamName = '';

// You may want to edit this function to suit your needs
String _getLogStreamName() {
  if (logStreamName == "") {
    logStreamName = DateFormat("yyyy-MM-dd HH-mm-ss").format(
      DateTime.now().toUtc(),
    );
  }
  return logStreamName;
}

void log(String logString, {isError = false}) {
  logging.log(
    msg: logString,
    logGroupName: isError ? logGroupName : logGroupNameError,
    logStreamName: _getLogStreamName(),
  );
}

void logFlutterSystemError(dynamic logString, dynamic stackTrace) async {
  log(
    'Auto Captured Error: ${logString.toString()}\n\n'
        'Auto Captured Stack Trace:\n${stackTrace.toString()}',
    isError: true,
  );
}

Then modify your main.dart to look like the following

import 'dart:async';
import 'app.dart';

import 'errorLog.dart';

void main() {
  runZonedGuarded<Future<void>>(() async {
    Function originalOnError = FlutterError.onError;
    FlutterError.onError = (FlutterErrorDetails errorDetails) async {
      Zone.current
          .handleUncaughtError(errorDetails.exception, errorDetails.stack);
      originalOnError(errorDetails);
    };
    runApp(MyApp());
  }, (error, stackTrace) async {
    logFlutterSystemError(error, stackTrace);
    print(error.toString());
    throw error;
  });
}

To send normal logs, import the logging file anywhere and call log('Hello world!');

Important Notes:

Avoiding AWS Cloudwatch API Rate Limiting

As of now (2021/07/09), AWS has a rate limit of 5 log requests per second per log stream. You may hit this limit rather quickly if you have a high volume of logs. It is highly recommended to include the optional delay parameter with a value of Duration(milliseconds: 200) to avoid hitting this upper limit. With a delay, logs will continue to collect, but the api calls will be limited to 1 / delay per second. For example, a delay of 200 milliseconds would result in a maximum of 5 api requests per second. At the moment there is no way to increase this limit.

[Example 2](#Example 2) shows how to add a delay. The default delay is Duration(milliseconds: 0).

Log Groups and Log Streams

There are multiple ways to set the log group and log stream and all are roughly equivalent.

Log stream names currently (2021/07/09) have the following limits:

Log stream names must be unique within the log group.
Log stream names can be between 1 and 512 characters long.
The ':' (colon) and '*' (asterisk) characters are not allowed.

This package does not enforce or check log stream names with regard to these limits in case AWS decides to add or remove limitations. It is up to you to check the errors returned by the API to figure out if the problem is with the provided log stream name.

eugenio165/Flutter_AWS_CloudWatch