$ docker-compose run app rspec --color specs
Building app
Step 1/6 : FROM ruby:2.7
 ---> fb53c5f433da
Step 2/6 : RUN mkdir /app
 ---> Using cache
 ---> 0d79a968fbbb
Step 3/6 : WORKDIR /app
 ---> Using cache
 ---> 20faa284ae78
Step 4/6 : ADD Gemfile Gemfile.lock /app/
 ---> 050ec65cce16
Step 5/6 : RUN bundle install -j 8
 ---> Running in 3102f1bf36cd
Fetching gem metadata from https://rubygems.org/..........
Using bundler 2.1.2
Fetching rspec-support 3.4.1
Fetching diff-lcs 1.2.5
Installing diff-lcs 1.2.5
Installing rspec-support 3.4.1
Fetching rspec-expectations 3.4.0
Fetching rspec-mocks 3.4.1
Fetching rspec-core 3.4.2
Installing rspec-core 3.4.2
Installing rspec-expectations 3.4.0
Installing rspec-mocks 3.4.1
Fetching rspec 3.4.0
Installing rspec 3.4.0
Bundle complete! 1 Gemfile dependency, 7 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.
Removing intermediate container 3102f1bf36cd
 ---> 417ad2370e72
Step 6/6 : ADD . /app
 ---> 593b562046e7
Successfully built 593b562046e7
Successfully tagged ruby-docker-example_app:latest
WARNING: Image for service app was built because it did not already exist. To rebuild this image you must use `docker-compose build` or `docker-compose up --build`.
.

Finished in 0.00044 seconds (files took 0.05898 seconds to load)
1 example, 0 failures