Overview

Send logged messages to AWS CloudWatch Logs using the ruby AWS SDK.

Can be used in place of Ruby's Logger (http://www.ruby-doc.org/stdlib/libdoc/logger/rdoc/)

In fact, it (currently) returns an instance of Logger.

Forked from loggiler.

Usage

require 'cloudwatchlogger'

log = CloudWatchLogger.new({access_key_id: 'YOUR_ACCESS_KEY_ID', secret_access_key: 'YOUR_SECRET_ACCESS_KEY'}, 'YOUR_CLOUDWATCH_LOG_GROUP')

log.info("Hello World from Ruby")

The region will default to the value of the environment variable AWS_REGION. In case you need to pass different region or group's different Log Stream name:

log = CloudWatchLogger.new({
  access_key_id: 'YOUR_ACCESS_KEY_ID',
  secret_access_key: 'YOUR_SECRET_ACCESS_KEY'
}, 'YOUR_CLOUDWATCH_LOG_GROUP', 'YOUR_CLOUDWATCH_LOG_STREAM', region: 'YOUR_CLOUDWATCH_REGION' )

Providing an empty hash instead of credentials will cause the AWS SDK to search the default credential provider chain for credentials, namely:

1. Environment variables AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
2. Amazon ECS container credentials (task role)
3. Instance profile credentials (IAM role)

Besides the AWS region, you can also specify some other configuration options for your logger, such as:

Property	Description
region	AWS region.
format	The output format of your messages. :json generates JSON logs for hashed messages.
open_timeout	The open timeout in seconds. Defaults to 120.
read_timeout	The read timeout in seconds. Defaults to 120.

This way, you could have something like this:

log = CloudWatchLogger.new({
    access_key_id: 'YOUR_ACCESS_KEY_ID',
    secret_access_key: 'YOUR_SECRET_ACCESS_KEY'
  }, 'YOUR_CLOUDWATCH_LOG_GROUP', 'YOUR_CLOUDWATCH_LOG_STREAM',
  {
    region: 'YOUR_CLOUDWATCH_REGION',
    format: :json
  })

With Rails

config/environments/production.rb

RailsApplication::Application.configure do
  config.logger = CloudWatchLogger.new({access_key_id: 'YOUR_ACCESS_KEY_ID', secret_access_key: 'YOUR_SECRET_ACCESS_KEY'}, 'YOUR_CLOUDWATCH_LOG_GROUP')
end

With Rails 4

config/initializers/cloudwatchlogger.rb

cloudwatchlogger = CloudWatchLogger.new({access_key_id: 'YOUR_ACCESS_KEY_ID', secret_access_key: 'YOUR_SECRET_ACCESS_KEY'}, 'YOUR_CLOUDWATCH_LOG_GROUP')
Rails.logger.extend(ActiveSupport::Logger.broadcast(cloudwatchlogger))

Logging

CloudWatchLogger.new returns a ruby Logger object, so take a look at:

http://www.ruby-doc.org/stdlib/libdoc/logger/rdoc/

The Logger's logdev has some special format handling though.

Logging a string

log.warn "test"

Will produce the following log message in CloudWatch Logs:

"<Date> severity=WARN, test"

Logging a Hash

log.warn :boom => :box, :bar => :soap

Will produce the following log message in CloudWatch Logs:

"<Date> severity=WARN, boom=box, bar=soap"

Custom Log Formatters

The default formatter in this gem ensures that the timestamp sent to cloudwatch will reflect the time the message was pushed onto the queue. If you want to use a custom log formatter, in order for you to not have a disparity between your actual log time and the time reflected in CloudWatch, you will need to ensure your formatter is a Hash with a key for message which will contain your log message, and epoch_time which should be an epoch time formatted timestamp for your log entry, like so:

logger.formatter = proc do |severity, datetime, progname, msg|
  {
    message:    "CUSTOM FORMATTER PREFIX: #{msg}\n",
    epoch_time: (datetime.utc.to_f.round(3) * 1000).to_i
  }
end

Releasing

rake release

Bugs

https://github.com/zshannon/cloudwatchlogger/issues

Pull requests welcome.