nat-monitor

Monitors a quorum of NAT servers for an outage and reassigns the specified EC2 route table to point to a working server.

Requirements

The basic AWS setup required to make this work is actually pretty complex. I recommend reading my how-to blog post. Feedback is highly appreciated.

Installation

Add this line to your application's Gemfile:

gem 'nat-monitor'

And then execute:

$ bundle

Or install it yourself as:

$ gem install nat-monitor

Usage

Run it as a service after creating the configuration YAML file.

E.g.:

$ nat-monitor [OPTIONAL CONF_FILE]

By default it will check /etc/nat_monitor.yml for its configuration.

Example Configuration

---
route_table_id: rtb-00000001
nodes:
  i-00000001: 10.0.0.1
  i-00000002: 10.0.1.1
  i-00000003: 10.0.2.1

Optional properties include (Values shown are the defaults):

pings: 3
ping_timeout: 1
heartbeat_interval: 10
monitor_enabled: false

Optional AWS configuration include:

aws_access_key_id: YOUR ACCESS KEY
aws_secret_access_key: YOUR SECRET KEY
region: us-east-1

Note that:

• If you don't specify the AWS credentials it will use the IAM role of the instance

The NAT Monitor has the ability to report out to Cronitor.io its status. This comes courtesy of the cronitor gem.

You will need to set monitor_enabled: true and then supply either a Cronitor API token & monitor options:

monitor_enabled: true
monitor_token: abcd
monitor_opts:
  name: My Fancy Monitor
  notifications:
    emails:
      - [email protected]
    slack:
      - https://url-to-slack.webhook
    pagerduty:
      - pagerduty-service-api-token
    phones:
      - +12345678900
    webhooks:
      - 'http://example.com'
  rules:
    - rule_type: 'not_run_in',
      duration: 5,
      time_unit: 'seconds'

or the code for an existing Cronitor monitor:

monitor_enabled: true
monitor_code: abcd

Contributing

1. Fork it ( https://github.com/evertrue/nat-monitor/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request