28 Mar 2013
- nginx - http reverse proxy server
- puma - ruby app server
- mysql - database server
- memcached - cache server
- sphinx - full text search server
- delayed_job - background job process
As you can see, it has multiple dependencies, if one of these processes stopped, the website is down or some features disabled. It's very common that your processes are terminated, like the host is power outage or cpu / memory usage is too high. So you need a tool that can monitor your processes and restart them automatically after crashed.
Generally you have 2 choices: god and monit, both of them work well. God is a ruby gem, monit is a more generic monitoring tool, they can monitor servers, processes, send notifications if resource usage is higher than you expected, they can restart your processes if crashed, they also provide terminal and web ui to check processes status.
Here is the god status
$ god status conferences-box-server: conferences-box-server.1: up conferences-box-server.2: up
Monit status looks more powerful
$ sudo monit status The Monit daemon 5.0.3 uptime: 2d 18h 15m System 'app.railsbp.com' status running monitoring status monitored load average [0.00] [0.04] [0.05] cpu 0.0%us 0.0%sy 0.0%wa memory usage 499136 kB [48.5%] data collected Thu Mar 28 10:12:19 2013 Process 'memcached' status running monitoring status monitored pid 2246 parent pid 1 uptime 8d 18h 13m children 0 memory kilobytes 20628 memory kilobytes total 20628 memory percent 2.0% memory percent total 2.0% cpu percent 0.0% cpu percent total 0.0% data collected Thu Mar 28 10:12:19 2013
After using them, I never worried if rails-bestpractices.com is down, even after a server restart. :-)