Also, I forgot the following fun fact about Heroku's cron service. This was true when I investigated it; might still be true now - not sure.
Since your app runs on X Heroku VMs, where X is often > 1, then, when you use Heroku's cron, the cronjob is executed on each box simultaneously -> unless you do something clever (and I was unable to figure out what that something clever is), X email processor instances run at the same time. If you need guarantee that each email is processed once only, this will screw it up for you. On Wed, Oct 7, 2009 at 11:05 AM, Yuri Niyazov <[email protected]> wrote: > I haven't checked out the online cron services yet, but there's > another issue that I had to solve, and I don't know whether they would > support this or not: > > Heroku limits the execution time of every request to 30 seconds each, > and a request that takes longer than that is abruptly interrupted. > This means that the magic URL handler has to be written in such a way > that it doesn't take longer than 30 secs; I decided to take the > dirty-hack approach to this: the URL handler processes two emails at a > time (let's say that 30 seconds is almost always enough to open an > IMAP connection, do a search, and download the text of two emails). > However, the URL handler checks the total number of messages to be > processed, and returns a status code for same. So: > > upto = 2 > msg_id_list = imap.search(["NOT", "DELETED"]) > msg_id_list = msg_id_list[0, upto] if upto > msg_id_list.each do |msg_id| > m = imap.fetch(msg_id, "RFC822")[0].attr["RFC822"] > process m > end > render :json => msg_id_list.to_json > > > and then in the script on the cron-box: > > do > msg_id_list = call_url.parse_json > until msg_id_list.empty? > > > As far as the Google indexing your URL issue: make sure that the GET > request returns a blank page, and the POST actually executes the > cronjob. And, of course, you can always protect that URL via > basic-auth or authenticity-token. > > On Wed, Oct 7, 2009 at 7:42 AM, Wojciech <[email protected]> wrote: >> >>> so I have a separate box with actual crond on it, and >>> it has a script that hits a specific URL on my app on heroku every x >>> minutes to process email. >> >> There are services that do it for you (i.e. periodically call your >> magic URL): >> http://www.onlinecronservices.com/ >> >> But be careful: this URL could be called by anybody and could even get >> indexed by Google. You might allow only certain IPs (ip of your online >> cron service) to call this URL to protect the app. >> >> There's also this "poor man's cron" approach, I've seen in Drupal: >> http://drupal.org/project/poormanscron - but it's a bit crazy. >> >> Cheers, >> Wojciech >> >>> >>> On Tue, Oct 6, 2009 at 3:06 PM, Carl Fyffe <[email protected]> wrote: >>> >>> > Rails makes it so easy to send emails. Recieving emails isn't that >>> > difficult either, but requires a cron or daemon. What is the best way >>> > to do this on Heroku today? >>> >>> > Carl >>> >>> >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Heroku" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/heroku?hl=en -~----------~----~----~----~------~----~------~--~---
