FitterHappier 
FitterHappier provides actions for monitoring a rails site and database availability. FitterHappier's monitoring controller disables unnecessary Rails features, like sessions, layouts, and logging, for lightning-fast monitoring URIs.
FitterHappier provides three monitoring URIs
% curl localhost:3000/fitter_happier
FitterHappier Site Check Passed
% curl localhost:3000/fitter_happier/site_check
FitterHappier Site Check Passed @ Wed, 17 Dec 2008 14:27:47 -0800
% curl localhost:3000/fitter_happier/site_and_database_check
FitterHappier Site and Database Check Passed @ Wed, 17 Dec 2008 14:27:57 -0800
Schema Version: 20081217141904
Note: to disable output from Rails Footnotes append '?footnotes=false' to the URIs above. Of course, Rails Footnotes is not recommended for production use.
Installation
Add the following to your gemfile
gem 'fitter-happier'
Monit
You can do simple checks with monit like this:
if failed host 127.0.0.1 port 5000
protocol HTTP request /fitter_happier with checksum 15b8a1ee66d740fbfc00297684bb5430 then restart
Keepalived/LVS
You can also do this in a keepalived/LVS setup:
virtual_server 169.254.y.z 80 {
delay_loop 15
lb_algo lc
lb_kind NAT
nat_mask 255.255.255.0
persistence_timeout 0
protocol TCP
sorry_server 127.0.0.1 80
virtualhost www.myfacetube.com
real_server 10.0.1.34 80 {
weight 1
HTTP_GET {
url {
path /fitter_happier
status_code 200
}
connect_port 80
connect_timeout 5
nb_get_retry 20
delay_before_retry 2
}
}
real_server 10.0.1.35 80 {
weight 1
HTTP_GET {
url {
path /fitter_happier
status_code 200
}
connect_port 80
connect_timeout 5
nb_get_retry 20
delay_before_retry 2
}
}
}