spree-extensions

Spree Extensions

Commands below use the Spree CLI form (spree …, Docker). On a classic Rails app without the CLI (typical pre-5.4), use the native mapping in the spree-project skill — bin/rails / bundle exec rake from the app root, paths without the backend/ prefix.

This skill covers two distinct things: installing a third-party Spree gem (spree_stripe, spree_i18n, etc.) and building your own extension to share across multiple Spree apps. For single-app customization (the 99% case), use the spree-customization skill to find the right pattern — usually it's a subscriber, dependency injection, or a decorator, not a gem.

Spree extensions are Rails engines packaged as gems. They mount into the host Rails app the same way Spree itself does. Adding one is a Gemfile entry + a generator run + a migrate.

Installing an extension

Three steps. Same pattern for every Spree extension. Requires the ejected dev stack: fresh create-spree-app projects run a prebuilt image where backend/ is not mounted into the container — run spree eject once first to switch to the bind-mounted dev compose.

# 1. Add to Gemfile
echo "gem 'spree_reviews'" >> backend/Gemfile

# 2. Install the gem
spree bundle install

# 3. Run the extension's install generator
spree rails g spree_reviews:install

The install generator is a convention — every Spree extension provides one at <gem_name>:install. It typically:

• Copies migrations into your app (db/migrate/<ts>_<name>.<gem_name>.rb)
• Adds an initializer (config/initializers/<gem_name>.rb)
• Registers itself with Spree.dependencies or Spree.subscribers if needed
• Sometimes copies admin views or installs admin slot extensions

After the install generator runs, apply migrations and restart:

spree migrate
spree dev                 # Ctrl+C the running one first; `spree restart` does not reload Gemfile changes

Extension gems bundled with create-spree-app

When you scaffold via npx create-spree-app, the resulting Gemfile already includes three payment providers plus i18n: