Oct 27th, 2019

Validating your CircleCI config

Did you know that you could validate your CircleCI config before pushing up your changes? Neither did I. I used to write my config, wait for CI to fail and then make the appropriate changes.

I got tired of doing that this morning, so decided to google “CircleCI config validator”. Guess what? I found one! Built by CircleCI themselves!

You can read their docs on it here.

But, here’s a quick TL;DR.

Installation

brew install --ignore-dependencies circleci

In my case, I didn’t need the package to install the “Docker for Mac” app since I already had it installed. For your specific needs, check out their installation section.

Usage

Once you have it installed, all you need to do is run:

circleci config validate

Example

Let’s say I did run the validator and had a syntax error, what would that look like?

➜  circleci config validate
Error: Unable to parse YAML
while scanning a simple key
 in 'string', line 36, column 7:
          run
          ^
could not find expected ':'
 in 'string', line 38, column 7:
          - run:
          ^

Whoa! This is awesome! No more useless commits.

What else can we do?

There is a bunch of other things we can do with this command, such as:

Packing a config
Processing a config (e.g. viewing the final output)
Run a job locally

How can we automate this?

As a consultant, I work across multiple projects and always look to automate and improve the developer experience. Knowing the above, I plan to create a utility for CircleCI projects to auto check the ci config as part of pre-commit git hook using lint-staged and husky.

So, what have we learned here?

A config validator exists
DevOps time can be cut by validating locally
There are several other useful commands available to you
This can be automated so we don’t have to think about it

I hope this was helpful to you.

Let me know what you think in the comments below.

Cheers!