Style guides

Editor/IDE styling standardization

We use EditorConfig to automatically apply certain styling standards before files are saved locally. Most editors/IDEs will honor the .editorconfig settings automatically by default. If your editor/IDE does not automatically support .editorconfig, we suggest investigating to see if a plugin exists. For instance here is the plugin for vim.

Pre-commit static analysis

You're strongly advised to install Overcommit to automatically check for static analysis offenses before committing locally.

In your GitLab source directory run:

cd tooling/overcommit && make && cd -

Then before a commit is created, Overcommit will automatically check for RuboCop (and other checks) offenses on every modified file.

This saves you time as you don't have to wait for the same errors to be detected by the CI.

Overcommit relies on a pre-commit hook to prevent commits that violate its ruleset. If you wish to override this behavior, it can be done by passing the ENV variable OVERCOMMIT_DISABLE; i.e. OVERCOMMIT_DISABLE=1 git rebase master to rebase while disabling the Git hook.

Ruby, Rails, RSpec

Our codebase style is defined and enforced by RuboCop.

You can check for any offenses locally with bundle exec rubocop --parallel. On the CI, this is automatically checked by the static-analysis jobs.

For RuboCop rules that we have not taken a decision on yet, we follow the Ruby Style Guide, Rails Style Guide, and RSpec Style Guide as general guidelines to write idiomatic Ruby/Rails/RSpec, but reviewers/maintainers should be tolerant and not too pedantic about style.

Similarly, some RuboCop rules are currently disabled, and for those, reviewers/maintainers must not ask authors to use one style or the other, as both are accepted. This isn't an ideal situation since this leaves space for bike-shedding, and ideally we should enable all RuboCop rules to avoid style-related discussions/nitpicking/back-and-forth in reviews.

Additionally, we have a dedicated newlines styleguide, as well as dedicated test-specific style guides and best practices.

Database migrations

See the dedicated Database Migrations Style Guide.


See the dedicated JS Style Guide.


See the dedicated SCSS Style Guide.


See the dedicated Go standards and style guidelines.

Shell commands (Ruby)

See the dedicated Guidelines for shell commands in the GitLab codebase.

Shell scripting

See the dedicated Shell scripting standards and style guidelines.


We're following Ciro Santilli's Markdown Style Guide.


See the dedicated Documentation Style Guide.


See the dedicated Python Development Guidelines.


Code should be written in US English.

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