Are there any tools that I can run on my server to monitor multiple rails applications?
I need to monitor the number of requests each application receives, how much memory each application is using, how much of the cpu is being used and other stats similar to those. I need to see the stats for each individual rails application.
I recommend you try NewRelic RPM.
The free version:
RPM Lite is the most widely used solution for basic web application monitoring. RPM Lite provides application monitoring for unlimited Java, Ruby or JRuby applications, for unlimited users, for an unlimited time. What a deal! With RPM Lite you can identify overall app health, app response time, throughput, Apdex SLA scoring, cluster breakdown, and Notes. You can also see where web transactions are spending the most time, isolate the worst offenders, and determine where to focus your remediation efforts
Later edit:
An alternative to NewRelic RPM is ScoutApp, that has a lot of plugins covering all your required features.
If you need something that can be run on your server, there is also the munin plugins gem that you may try. If you need a users monitoring tools (kind of like Google Analytics)m you can use the RailStat gem.
The Request Log Analyzer gem can be useful, is free, and works by analyzing Rails log files. Thus, there's no chance of it having any negative impact on your application's performance.
来源：https://stackoverflow.com/questions/3500761/monitor-multiple-rails-applications