Spurious CORS Errors from Sentry

I realised the other day that Sentry, the awesome system we have been using for a while to track our error logs from our Django project, can also be used to track exceptions from other systems. Like Javascript. In fact, there is a client available: raven.js.

So, we have a server set up for work, but I have a side-project I have been working on, Workout Builder. So, I thought I’d set up a server in Heroku to act as my sentry server. And I found a nice simple way to get up and running: Daniel Watkins has a nice post over at Odd_Blog, Deploying Sentry on Heroku.

It’s pretty straightforward, and extremely simple. I got it up and running in no time, and then attempted to set up an email service. Rather than use my actual account for sending, I thought I’d set up a sending-only account at my domain, hosted as a Gmail Apps domain. So, I set it up, and set about testing.

All of a sudden, I’m getting errors, that didn’t appear for 30 seconds, that my test domain is not permitted to send a request due to CORS. But, I had been sending them previously.

After lots of dicking around, I discovered it was because I did not have the gmail settings quite right. Instead of telling me what the problem was, something was masking the issue (that the server was timing out because the server/port combination was not correct), and jQuery thought it was a CORS issue.

So, fixing up the email sending settings, and it’s all gravy:

EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'

EMAIL_HOST = 'smtp.gmail.com'
EMAIL_HOST_PASSWORD = '<oh no you don\'t>'
EMAIL_HOST_USER = 'noreply@schinckel.net'

Initially, I had used mail.google.com, port 25, and EMAIL_USE_TLS = False. Eventually, I got it all right.