Inspired by the ease of installing and setting up fitter-happier as a Rails application's health check, but frustrated by its lack of flexibility, OK Computer was born. It provides a robust endpoint to perform server health checks with a set of built-in plugins, as well as a simple interface to add your own custom checks.
For more insight into why we built this, check out our blog post introducing OK Computer.
OkComputer currently supports the following Rails versions:
Not using Rails?
Add this line to your application's Gemfile:
And then execute:
Or install it yourself as:
$ gem install okcomputer
To perform the default checks (application running and ActiveRecord database connection), do nothing other than adding to your application's Gemfile.
If Not Using ActiveRecord
We also include a MongoidCheck, but do not register it. If you use Mongoid, replace the default ActiveRecord check like so:
OkComputer::Registry.register "database", OkComputer::MongoidCheck.new
If you use another database adapter, see Registering Custom Checks below to
build your own database check and register it with the name "database" to
replace the built-in check, or use
to stop checking your database altogether.
Optionally require HTTP Basic authentication to view the results of checks in an initializer, like so:
# config/initializers/okcomputer.rb OkComputer.require_authentication("username", "password")
To allow access to specific checks without a password, optionally specify the names of the checks:
# config/initializers/okcomputer.rb OkComputer.require_authentication("username", "password", except: %w(default nonsecret))
Changing the OkComputer Route
By default, OkComputer routes are mounted at
/okcomputer. If you'd like to use an alternate route,
you can configure it with:
# config/initializers/okcomputer.rb OkComputer.mount_at = 'health_checks' # mounts at /health_checks
For more control of adding OkComputer to your routes, set
OkComputer.mount_at = false to disable automatic mounting, and you can manually mount the engine
# config/initializers/okcomputer.rb OkComputer.mount_at = false # config/routes.rb, at any priority that suits you mount OkComputer::Engine, at: "/custom_path"
Logging check results
Log check results by setting
OkComputer.logger. Note: results will be logged at the
OkComputer.logger = Rails.logger
[okcomputer] mycheck: PASSED mymessage (0s)
Registering Additional Checks
Register additional checks in an initializer, like so:
# config/initializers/okcomputer.rb OkComputer::Registry.register "resque_down", OkComputer::ResqueDownCheck.new OkComputer::Registry.register "resque_backed_up", OkComputer::ResqueBackedUpCheck.new("critical", 100) # This check works on 2.4.0 and above versions of resque-scheduler OkComputer::Registry.register "resque_scheduler_down", OkComputer::ResqueSchedulerCheck.new
Registering Custom Checks
The simplest way to register a check unique to your application is to subclass
OkComputer::Check and implement your own
#check method, which sets the
display message with
mark_message, and calls
mark_failure if anything is
# config/initializers/okcomputer.rb class MyCustomCheck < OkComputer::Check def check if rand(10).even? mark_message "Even is great!" else mark_failure mark_message "We don't like odd numbers" end end end OkComputer::Registry.register "check_for_odds", MyCustomCheck.new
Registering Optional Checks
Register an optional check like so:
# ... OkComputer::Registry.register "some_optional_check", OkComputer::ResqueBackedUpCheck.new("critical", 100) # ... OkComputer.make_optional %w(some_optional_check another_optional_check)
This check will run and report its status, but will not affect the HTTP status code returned.
Customizing plain-text output
The plain-text output flows through Rails' internationalization framework.
Adjust the output as necessary by defining
okcomputer.check.failed keys in your setup. The default values are available
Running checks in parallel
By default, OkComputer runs checks in sequence. If you'd like to run them in parallel, you can configure it with:
# config/initializers/okcomputer.rb OkComputer.check_in_parallel = true
- Perform a simple up check: http://example.com/okcomputer
- Perform all installed checks: http://example.com/okcomputer/all
- Perform a specific installed check: http://example.com/okcomputer/database
Checks are available as plain text (by default) or JSON by appending .json, e.g.:
OkComputer NewRelic Ignore
If NewRelic is installed, OkComputer automatically disables NewRelic monitoring for uptime checks, as it will start to artificially bring your request time down.
If you'd like to intentionally count OkComputer requests in your NewRelic analytics, set:
# config/initializers/okcomputer.rb OkComputer.analytics_ignore = false
$ bundle install
Running the test suite
OkComputer tests are written with RSpec.
To run the full test suite:
$ rake spec
You may also use the environment variable
RAILS_VERSION with one
of the supported versions of Rails (found at the top of this file) to
bundle and run the tests with a specific version of Rails.
- 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