Example services monitor and corresponding simulator using Ruby and ZooKeeper.
Often times, it is beneficial to allow services to publish their presence in order for other services to subscribe/connect with them. This project simulates multiple services 'subscribing' and 'unsubscribing' using ephemeral nodes in ZooKeeper. The Service Monitor instance watches for subscriptions/un-subscribes, and publishes information about which services are currently available, subscribing, and un-subscribing.
Reference the Apache ZooKeeper website on how to install/start the ZooKeeper service:
Set up the required Ruby Gems:
$ bundle install
Update the following file to reflect the configuration for your environment:
$ vim config/settings
The usage of this project is best performed in multiple (side-by-side) terminal windows. There are 2 different monitors that can be utilized - the 'service' monitor and the 'terminal' monitor.
The Service monitor outputs the status of registered/un-registered services in a log-like fashion.
Start an instance of the Service Monitor (terminal instance #1):
$ ruby lib/service_monitor.rb
# Service Monitor Initializing... [ OK ]
Start the simulator (terminal instance #2):
$ ruby lib/simulator.rb
# Simulator Thread Initialized for Service with IP: 10.0.24.2
# Simulator Thread Initialized for Service with IP: 10.0.24.3
# Simulator Thread Initialized for Service with IP: 10.0.24.4
# Simulator Thread Initialized for Service with IP: 10.0.24.5
# Simulator Thread Initialized for Service with IP: 10.0.24.6
...
Watch the Service Monitor track the services as they come online/register and leave/unregister (terminal instance #1):
...
# Service IPs Online: 10.0.24.10, 10.0.24.3, 10.0.24.4, 10.0.24.12, 10.0.24.7, 10.0.24.8, 10.0.24.9
# Service(s) with IP 10.0.24.9 Un-Registered
# Service IPs Online: 10.0.24.10, 10.0.24.3, 10.0.24.4, 10.0.24.12, 10.0.24.7, 10.0.24.8
# ============================================================================
# SERVICE (10.0.24.10) | Processing (8962) | Capacity remaining (1038)
# SERVICE (10.0.24.3) | Processing (8109) | Capacity remaining (1891)
# SERVICE (10.0.24.4) | Processing (9913) | Capacity remaining (87)
# SERVICE (10.0.24.12) | Processing (7229) | Capacity remaining (2771)
# SERVICE (10.0.24.7) | Processing (6157) | Capacity remaining (3843)
# SERVICE (10.0.24.8) | Processing (4948) | Capacity remaining (5052)
# ============================================================================
# Service(s) with IP 10.0.24.13 Registered
# Service IPs Online: 10.0.24.10, 10.0.24.3, 10.0.24.4, 10.0.24.12, 10.0.24.7, 10.0.24.13, 10.0.24.8
# Service(s) with IP 10.0.24.3 Un-Registered
# Service IPs Online: 10.0.24.10, 10.0.24.4, 10.0.24.12, 10.0.24.7, 10.0.24.13, 10.0.24.8
# Service(s) with IP 10.0.24.4 Un-Registered
# Service IPs Online: 10.0.24.10, 10.0.24.12, 10.0.24.7, 10.0.24.13, 10.0.24.8
# ============================================================================
# SERVICE (10.0.24.10) | Processing (8962) | Capacity remaining (1038)
# SERVICE (10.0.24.12) | Processing (7229) | Capacity remaining (2771)
# SERVICE (10.0.24.7) | Processing (6157) | Capacity remaining (3843)
# SERVICE (10.0.24.13) | Processing (9671) | Capacity remaining (329)
# SERVICE (10.0.24.8) | Processing (475) | Capacity remaining (9525)
# ============================================================================
# Service(s) with IP 10.0.24.13 Un-Registered
# Service IPs Online: 10.0.24.10, 10.0.24.12, 10.0.24.7, 10.0.24.8
# ============================================================================
# SERVICE (10.0.24.10) | Processing (8901) | Capacity remaining (1099)
# SERVICE (10.0.24.12) | Processing (1358) | Capacity remaining (8642)
# SERVICE (10.0.24.7) | Processing (7357) | Capacity remaining (2643)
# SERVICE (10.0.24.8) | Processing (4639) | Capacity remaining (5361)
# ============================================================================
...
The Terminal monitor outputs and updates the status of registered/un-registered services in-place (simulating the Linux "top" command).
Start an instance of the Terminal Monitor - note that your screen will most likely go blank except for the "...Initializing..." message (terminal instance #1):
$ ruby lib/terminal_monitor.rb
# Terminal Monitor Initializing... [ OK ]
Start the simulator (terminal instance #2):
$ ruby lib/simulator.rb
# Simulator Thread Initialized for Service with IP: 10.0.24.2
# Simulator Thread Initialized for Service with IP: 10.0.24.3
# Simulator Thread Initialized for Service with IP: 10.0.24.4
# Simulator Thread Initialized for Service with IP: 10.0.24.5
# Simulator Thread Initialized for Service with IP: 10.0.24.6
...
Watch the Terminal Monitor track the services as they come online/register and leave/unregister - the services will automatically be added/removed/updated as they register/unregister/update (terminal instance #1):
=======================================================
| IP Address | Processing | Available |
=======================================================
| 10.0.24.2 | 555 | 445 |
| 10.0.24.4 | 61 | 939 |
| 10.0.24.5 | 754 | 246 |
| 10.0.24.6 | 80 | 920 |
| 10.0.24.7 | 151 | 849 |
| 10.0.24.8 | 505 | 495 |
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request