Rails - Providing License Key to Plugin Based on Hostname

Question

I'm using New Relic for Rails, but only need New Relic to monitor my one production environment. However, I have a staging server that also runs in Production mode. New Relic detects both as operating prod instances of my application (as it should), but I don't want to have to pay for monitoring two instances when I only want to keep an eye on the one.

New Relic accepts an environment variable for the license key:

license_key: <%= ENV['NEWRELIC_ACCOUNT_KEY'] %>

Is it possible to detect the hostname in the environment files (i.e. config/environments/production.rb) so that I can define this environment variable dynamically?

Both environments are deployed from the same Git repository, same source code base, so I can't really change it in the code for each deploy - it would be best to be able to define the environment variable dynamically somehow.

Any thoughts would be appreciated! Thanks!

Answer 1

The New Relic Ruby agent will parse the newrelic.yml configuration file as ERB before parsing it as YAML. Therefore, you can do lots of neat tricks, such as:

production:
  license_key: <%= Socket.gethostname == 'mission-critical.example.com' ? 'PAID_ACCOUNT_LICENSE_KEY' : 'FREE_LITE_ACCOUNT_LICENSE_KEY' %>

This parsing all happens at app boot time.

If your RAILS_ENV were different from 'production' in that staging server that runs "in Production mode", then you could just use the environment sections as Steve Graham suggests.

Answer 2

Have you created a separate environment for staging? i.e. development, test, production, and staging? See here for instructions…

Having done that, one can specify behaviour for that environment in config/newrelic.yml

common: &default_settings
  license_key: 'PASTE_YOUR_KEY_HERE'
  …

development:
  enabled: false
  …

test:
  enabled: false
  …

production:
  enabled: true
  …

staging: 
  enabled: false
  …

etc, etc