I was working on a problem this weekend - not a super hard problem - but an annoying one:
When you've got a system that is supposed to trigger at certain times, how can you verify that it's actually happening?
The system I was working with is web based - hit a specific URL at a specific time. It’s called keepalive and it runs on Heroku. It hits a few URLs daily - but I wanted to make sure:
- It was working at all.
- It was happening at the right time.
So I built a quick little hack to do that - trigger emails when a specific URL is hit - and I uploaded it to Heroku.
I felt a little guilty when I added it to Heroku, because we’re building octohost and this seemed like a perfect fit - a simple little web app with no database requirement. But octohost didn’t have one thing I really liked to use: easily updatable environment variables. I really like Heroku’s 12 factor pattern - especially when it relates to configuration information.
On Sunday, I rebuilt the ‘quick little hack’ that I made on Saturday night and added a bunch of new features - I called it Canary. By the way - Canary did help me to see that keepalive was working correctly (other than the DST change) - so it fulfilled its purpose.
Monday morning I decided I’d add some easily configured environment variables to octohost. I patterned them after Heroku’s Config Vars.
It’s pretty easy to use:
octohost:/home/git# octo config canary
/canary/SESSION_SECRET:long-random-looking-string-that-will-not-be-posted
/canary/SENDGRID_PASSWORD:not-the-password
/canary/SENDGRID_USERNAME:not-the-username@example.com
/canary/EMAIL_DESTINATION:not-the-email-address@example.com
/canary/RACK_ENV:production
/canary/LANG:en_US.UTF-8
/canary/BASE_CANARY_PATH:octo
octohost:/home/git# octo config:set canary/TESTING "This is only a test."
This is only a test.
octohost:/home/git# octo config canary
/canary/SESSION_SECRET:long-random-looking-string-that-will-not-be-posted
/canary/SENDGRID_PASSWORD:not-the-password
/canary/SENDGRID_USERNAME:not-the-username@example.com
/canary/EMAIL_DESTINATION:not-the-email-address@example.com
/canary/RACK_ENV:production
/canary/LANG:en_US.UTF-8
/canary/BASE_CANARY_PATH:octo
/canary/TESTING:This is only a test.
octohost:/home/git# octo config:rm canary/TESTING
octohost:/home/git# octo config canary
/canary/SESSION_SECRET:long-random-looking-string-that-will-not-be-posted
/canary/SENDGRID_PASSWORD:not-the-password
/canary/SENDGRID_USERNAME:not-the-username@example.com
/canary/EMAIL_DESTINATION:not-the-email-address@example.com
/canary/RACK_ENV:production
/canary/LANG:en_US.UTF-8
/canary/BASE_CANARY_PATH:octo
I’m pretty happy with how it all turned out.
You can see Canary here - more information on octohost here.
NOTE: We’re only using octohost to serve really small sites at the moment. The more this works out, the more sites we’ll be able to use on it.