lita-heroku-keepalive

A gem that keeps the Lita Heroku free web dyno alive. Note that a free Heroku dyno can only run for 18 hours/day, so it will be required to sleep for at least 6 hours. Accessing your Lita during a sleep period will wake it, but it will return to sleep after 30 minutes.

Add lita-heroku-keepalive to your Lita instance's Gemfile:

gem "lita-heroku-keepalive"

And then execute:

$ bundle

install it yourself as:

$ gem install lita-heroku-keepalive

lita-heroku-keepalive is configured by four environment variables:

• LITA_HEROKU_KEEPALIVE_URL - required, the complete URL to keepalive, including a trailing slash.
• LITA_HEROKU_WAKEUP_TIME - optional, the time of day (HH:MM) when lita should wake up. Default: 6:00 (6 am)
• LITA_HEROKU_SLEEP_TIME - optional, the time of day (HH:MM) when lita should go to sleep. Default: 22:00 (10 pm)
• LITA_HEROKU_KEEPALIVE_INTERVAL - the interval minutes in which to keepalive, in minutes. Default: 5 (minutes)

You must set LITA_HEROKU_KEEPALIVE_URL and it must include a trailing slash – otherwise the script won't run. You can find out the value for this by running heroku apps:info. Copy the Web URL and run:

heroku config:set LITA_HEROKU_KEEPALIVE_URL=PASTE_WEB_URL_HERE

If you want to trust a shell snippet from the Internet, here's a one-liner:

heroku config:set LITA_HEROKU_KEEPALIVE_URL=$(heroku apps:info -s | grep web_url | cut -d= -f2)

LITA_HEROKU_WAKEUP_TIME and LITA_HEROKU_SLEEP_TIME define the waking hours - between these times the keepalive will ping your Heroku app. Outside of those times, the ping will be suppressed, allowing the dyno to shut down. These times are based on the timezone of your Heroku application which defaults to UTC. You can change this with:

heroku config:add TZ="America/New_York"

TODO: Describe the plugin's features and how to use them.

This gem will keep the dyno alive once it is awake, but something needs to wake it up. You can use the Heroku Scheduler to wake the dyno up. Add the scheduler addon by running:

heroku addons:create scheduler:standard

The scheduler must be manually configured from the web interface, so run heroku addons:open scheduler and configure it to run curl ${LITA_HEROKU_KEEPALIVE_URL}heroku/keepalive at the time configured for LITA_HEROKU_WAKEUP_TIME.

Note that the Scheduler's time is in UTC. If you changed your application's timezone with TZ, you'll need to convert that time to UTC for the wakup job. For example, if LITA_HEROKU_WAKEUP_TIME is set to 06:00 and TZ is set to America/New_York, you'll need to set the Scheduler to run at 10:00 AM UTC.