This time, I will summarize the errors that occurred when docker was installed in an existing application and the solutions.
Create docker file Why do you use the docker-compose build command after creating docker-compose.yml?
You must use Bundler 2 or greater with this lockfile.
An error has occurred.
I referred to the article on the net
RUN gem install bundler RUN bundle install
I bought that it would be cured if I wrote RUN gem install bundler before RUN bundle install, but I already wrote it.
While investigating, I found an article that such a bug occurs in the case of ruby 2.5.1, and as a result of changing the ruby version to 2.7.1 docker file local environment, this error was resolved.
ruby version change https://qiita.com/kanacan/items/c1499f6c13b1c41da982