Simple notes on how to run ruby in containers

docker_ruby.sh

# This is for running an irb 
docker run --it --rm ruby:2.5

# This is for running an script
docker run -it --rm --name my-running-script -v "$PWD":/usr/src/myapp -w /usr/src/myapp ruby:2.5 ruby hello_world.rb
# this is the content we should put in hello_world.rb Make sure to add the first line
# #!/usr/bin/env Ruby
# puts Hello World from Dockerfile
# we also need to make the script executable
chmod u+x hello_world.rb 

# This is for running an script via Dockerfile
mkdir hello_world
cd hello_world/
vim Dockerfile
# this is the content we should put in Dockerfile
# FROM ruby:2.5
## throw errors if Gemfile has been modified since Gemfile.lock
# RUN bundle config --global frozen 1
# WORKDIR /usr/src/app
# COPY Gemfile Gemfile.lock ./
# RUN bundle install
# COPY . .
# CMD ["./hello_world.rb"]
vim hello_world.rb
# this is the content we should put in hello_world.rb
# puts "Hello World"
vim Gemfile
# this is the content we should put in Gemfile
# source 'https://rubygems.org' do
## Gems here
#end

# since Dockerfile is expecting a Gemfile.lock we should generate it
docker run --rm -v "$PWD":/usr/src/app -w /usr/src/app ruby:2.5 bundle install

# and then we should run this command to build the image
docker build -t my-ruby-app .
# if we want to run the image 
docker run -it --rm --name my-running-script my-ruby-app