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!