Replacing Pingdom with Ruby and Heroku

Pingdom recently increased the price of the starting plan from $10 to $14. Since they didn’t keep the price for older customers, I decided to create something to replace it, because the new pricing is just too much for my personal sites.

This article shows how you can set up your own uptime checker and run it on Heroku for $7/month.

About uptime_checker

I created uptime_checker, which has less than 500 lines. The main features are:

• Several notification mechanisms (Telegram, Twitter’s Direct Message, E-mail, Slack, Hipchat, and more)
• Easy to set up on Heroku
• Easy to define the sites that will be monitored

The idea is pretty simple: hit the urls you define every 30s (configurable) and see if the site returns the expected status code. You can also check if the response contains a string. If the status/body is not what you expected, it notifies you.

Running uptime_check on Heroku is really easy and you won’t need more than a few minutes, so let’s do it.

Setting up uptime_checker

First, you have to fork the repository, since you have to create your own branch with a configuration file. Go to Github and hit the “Fork” button.

Now, clone the repository and create a new branch: I’ll call it personal in this article.

$ git clone git@github.com:<your username>/uptime_checker.yml
$ cd uptime_checker
$ git checkout -B personal

Copy the sample configuration file.

$ cp checkers.yml.sample checkers.yml

Open the checkers.yml file. This file is where you define all the sites that must be monitored. It supports ERB, so you can render dynamic variables. Here’s is my own configuration file.

notify: &notify
  - twitter: fnando
  - email: fnando.vieira@gmail.com
  - stdout: ~
  - telegram: -97517324
  - noti: <%= ENV["NOTI_FNANDO"] %>

checkers:
  - name: Codeplane
    url: https://codeplane.com/
    notify: *notify
    status: 200

  - name: Codeplane
    url: https://codeplane.com.br/
    notify: *notify
    status: 200

  - name: Hellobits
    url: http://hellobits.com/
    notify: *notify
    status: 200

  - name: HOWTO
    url: http://howtocode.com.br/
    notify: *notify
    status: 200

  - name: Nando Vieira
    url: http://nandovieira.com/
    notify: *notify
    status: 200

  - name: Nando Vieira
    url: https://nandovieira.com.br/
    notify: *notify
    status: 200

  - name: Presentta
    url: https://presentta.com.br/
    notify: *notify
    status: 200

To avoid repeating the notifiers, I’m using the shared block trick. You can have different notifications for each site you’re monitoring if you need.

Notice that I’m expecting those sites to respond with a 200 status code, but you can also check if the response has some given text.

checkers:
  - name: Example
    url: http://example.com
    notify: *notify
    status: 200
    body: Some string

After you’re done, commit your changes.

$ git add .
$ git commit -m "Add checkers."
$ git push origin personal

Deploying to Heroku

Deploying uptime_checker to Heroku is the easiest way you can have this running. Assuming you already Heroku configured, create a new application.

$ heroku create

Redis is required, so we need to add the add-on.

$ heroku addons:create heroku-redis

To receive e-mail notifications, you’ll also need Sendgrid.

heroku addons:create sendgrid:starter

I use Noti. If you check the checkers example above, you’ll see that I’m using a NOTI_FNANDO environment variable. Let’s set that on Heroku:

$ heroku config:set NOTI_FNANDO=fc17d63d-5d3e-4532-98ed-b8047f0d5bc9

Now it’s time to deploy! Since we’ll deploy the personal branch, you have to use the following command:

$ git push heroku personal:master

This means that the personal branch will be pushed as Heroku’s master.

To run this 24/7 ($7/mo), we have to scale up our worker.

$ heroku ps:scale worker=1
$ heroku dyno:type worker=hobby

And we’re done! You can check the logs with heroku logs --tail.

app[worker.1]: enabled_notifiers="email, noti, stdout, telegram, twitter" time="2016-01-29T12:40:28Z"
app[worker.1]: message="starting check" url="https://presentta.com.br/" time="2016-01-29T12:40:28Z"
app[worker.1]: message="starting check" url="https://nandovieira.com.br/" time="2016-01-29T12:40:28Z"
app[worker.1]: message="starting check" url="http://nandovieira.com/" time="2016-01-29T12:40:28Z"
app[worker.1]: message="starting check" url="http://howtocode.com.br/" time="2016-01-29T12:40:28Z"
app[worker.1]: message="starting check" url="http://hellobits.com/" time="2016-01-29T12:40:28Z"
app[worker.1]: url="https://codeplane.com/" message="check finished" status="no changes" time="2016-01-29T12:40:28Z"
app[worker.1]: url="https://codeplane.com.br/" message="check finished" status="no changes" time="2016-01-29T12:40:28Z"
app[worker.1]: url="http://howtocode.com.br/" message="check finished" status="no changes" time="2016-01-29T12:40:28Z"
app[worker.1]: url="https://nandovieira.com.br/" message="check finished" status="no changes" time="2016-01-29T12:40:28Z"
app[worker.1]: url="https://presentta.com.br/" message="check finished" status="no changes" time="2016-01-29T12:40:28Z"

If you’re not into Heroku, you can also deploy it to a VPS. If you already know how to deploy a Rails application, you won’t have any problem. Since this involves too much things, I leave this as an exercise to the reader.

Keeping up with master

You may want to keep up with master, getting all the fixes and new features (if any). The workflow for updating your branch is pretty simple.

First, switch off to master and pull all the changes.

$ git checkout master
$ git pull

Then switch back to personal and apply master‘s onto it.

$ git checkout personal
$ git rebase master

Now, deploy the repository.

$ git push heroku personal:master -f

Wrapping up

That’s it! If you have any suggestions or need help, just open an issue.