Heroku provides a CI solution out of the box for teams. They can run tests in dyno instance for your project. What’s more interesting you can run parallel dynos as part of your CI build. This allows you to split tests on parallel dynos to complete CI build faster and save time.

Heroku charges you for seconds spent in runtime for each dyno. It means instead of running your slow test suite on a single dyno you could split it across multiple dynos and pay more or less the same and significantly reduce the CI build time for your project.

How to start with Heroku CI

If you or your company has already created a team in Heroku then you can use Heroku CI and run tests for your project there.

In Heroku, you can open your team and particular pipeline for one of your projects. You will find there a Tests tab where you can enable Heroku CI.

You will also need an app.json file in a repository of your project. The file contains information about what’s needed to run the project on Heroku. We will add to the app.json file additional configuration needed for Heroku CI.

In order to use Heroku CI parallel test runs, we need to have it enabled. You will have to ask Heroku support to activate it for your project. This feature allows to run up to 32 parallel dynos for your CI build.

You can also watch all the steps on more detailed video or copy some examples from this article.

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