Frontend gulp tasks are complicated and doing too many things

Cause

• There are loads of sequences that build on top of each other.
• There are tasks called both copy:assets and copy-assets.
• Tasks are sometimes in files with different names
• The scss:compile task is responsible for creating both the app CSS and the dist CSS, depending on a flag. The pipelines for these files are similar, but not identical, but completely different files are built depending on the flag.
• The js:compile task is responsible for creating both the app JS and the dist JS, depending on a flag. The pipelines for these files are similar, but not identical, but completely different files are built depending on the flag.

Consequences

• It’s hard to make changes to our build pipeline
• It’s hard for contributors to understand how our build pipeline works
• It’s easy to run the wrong task because there are many similarly named tasks or ways of running things (e.g. gulp directly vs npm scripts)
• We have a lot of dependencies, which means a greater attack surface, and more maintenance effort is required

Impact of debt

Medium, it works most of the time, but there is a high risk of breaking things when changes are needed.

Effort to pay down

High, we don’t know enough about Gulp on the team, and we would want to be sure that any changes made don’t break the build or lose functionality we need

Overall rating:

Medium

[domoscargin]

Posting here to say that a lot of the dependency problems stem from our use of oldie for IE8 styles compilation, which clashes with bumping most other css-related dependencies (the package itself is a bit of an oldie - latest release 7 years ago!). We might want to consider removing IE8 support in our browser support breaking release before working on this, since we could make these changes without a breaking release.

edit: Aha, just found #2469

[lfdebrux]

@colinrotherham I wasn’t involved in writing the ticket (just copied it from an old Trello board https://github.com/alphagov/govuk-frontend/issues/2243#issuecomment-854727436), so possibly not the best person to ask, sorry!