Using docker where gems are pre-installed

.gitlab-ci.yml

-image: "ruby:2.3"
+image: "registry.gitlab.com/gitlab-org/gitlab-elasticsearch-git"
 services:
   - elasticsearch:5.1
@@ -6,11 +6,15 @@ services:
 variables:
   ELASTICSEARCH_HOST: "elasticsearch"
-before_script:
-  - apt-get update -yqqq; apt-get -o dir::cache::archives="vendor/apt" install -y -qq --force-yes libicu-dev cmake
-  - gem install bundler         # Bundler is not installed with the image
-  - bundle install -j $(nproc)  # Install dependencies
-
 rspec:
   script:
-  - rspec
+  - pwd
+  - whoami
+  - echo $GEM_HOME
+  - echo $BUNDLE_PATH
+  - echo $BUNDLE_BIN
+  - ls -la
+  - bundle install -j $(nproc)
+  - gem list
+  - bundle env
+  - bundle exec rspec spec

Dockerfile

+FROM ruby:2.3.3
+
+RUN apt-get -y update && apt-get install -y libicu-dev cmake
+RUN mkdir /temporary
+ADD . /temporary
+WORKDIR /temporary
+RUN gem install charlock_holmes -v '0.7.3'
+RUN bundle install