Docker Cannot link to a non running container

Question

I need to create Rails and Mysql containers with docker-compose. When I try to create links between containers with docker-compose up, I get

Cannot start container 9b271c58cf6aecaf017dadaf5b Cannot link to a non running container: /puma_db_1 AS /puma_web_1/db

Files

Dockerfile

FROM ubuntu:14.04

RUN apt-get -y update
RUN apt-get -y install git curl zlib1g-dev build-essential libssl-dev libreadline-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt1-dev libcurl4-openssl-dev python-software-properties libffi-dev

RUN apt-get -y install libmysqlclient-dev
RUN git clone https://github.com/sstephenson/rbenv.git /root/.rbenv
RUN git clone https://github.com/sstephenson/ruby-build.git /root/.rbenv/plugins/ruby-build
RUN echo 'eval "$(rbenv init -)"' >> $HOME/.profile
RUN echo 'eval "$(rbenv init -)"' >> $HOME/.bashrc

RUN rbenv install 2.1.5
RUN rbenv global 2.1.5
RUN gem install rails -v 4.0.11

ADD app.tar.gz /home/
WORKDIR /home/app

RUN bundle install
EXPOSE 3000
CMD ["rails", "server", "-b", "0.0.0.0"]

docker-compose.yml

db:  
  image: mysql:latest
  environment:
    MYSQL_DATABASE: app_development
    MYSQL_USER: mysql
    DATABASE_PASSWORD: onetwo
    ROOT_PASSWORD: onetwo
web:
  build: .
  command: bundle exec rails s -p 3000 -b '0.0.0.0'
  ports:
    - "4000:3000"
  links:
    - db

Answer 1

Most likely the db container fails to start.

Make sure it works fine by starting only the db service. You can do that with the following command:

docker-compose up db

If it appears the MySQL service is not running after this command, then you found the origin of your problem.