Prefer offline install for yarn

.gitlab/ci/frontend.gitlab-ci.yml

@@ -32,7 +32,7 @@
     DOCKER_HOST: tcp://docker:2375
   script:
     - node --version
-    - retry yarn install --frozen-lockfile --production --cache-folder .yarn-cache
+    - retry yarn install --frozen-lockfile --production --cache-folder .yarn-cache --prefer-offline
     - free -m
     - retry bundle exec rake gitlab:assets:compile
     - time scripts/build_assets_image
@@ -82,7 +82,7 @@ gitlab:assets:compile pull-cache:
   stage: prepare
   script:
     - node --version
-    - retry yarn install --frozen-lockfile --cache-folder .yarn-cache
+    - retry yarn install --frozen-lockfile --cache-folder .yarn-cache --prefer-offline
     - free -m
     - retry bundle exec rake gitlab:assets:compile
     - scripts/clean-old-cached-assets
@@ -231,7 +231,7 @@ qa:selectors:
   before_script: []
   script:
     - date
-    - yarn install --frozen-lockfile --cache-folder .yarn-cache
+    - yarn install --frozen-lockfile --cache-folder .yarn-cache --prefer-offline
     - date
     - yarn run webpack-prod
 

.gitlab/ci/review.gitlab-ci.yml

@@ -236,5 +236,5 @@ danger-review:
   script:
     - git version
     - node --version
-    - yarn install --frozen-lockfile --cache-folder .yarn-cache
+    - yarn install --frozen-lockfile --cache-folder .yarn-cache --prefer-offline
     - danger --fail-on-errors=true

lib/tasks/yarn.rake

@@ -24,7 +24,7 @@ namespace :yarn do
 
   desc 'Install Node dependencies with Yarn'
   task install: ['yarn:available'] do
-    unless system('yarn install --pure-lockfile --ignore-engines')
+    unless system('yarn install --pure-lockfile --ignore-engines --prefer-offline')
       abort 'Error: Unable to install node modules.'.color(:red)
     end
   end