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
>>
>>
> >
>
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