Rails fails to start on docker - ruby-on-rails

Question

I'm trying to setup my rails application to run using docker. It keeps crashing with Could not find rake-12.3.2 in any of the sources (Bundler::GemNotFound)
Dockerfile
FROM ruby:2.6.1
RUN apt-get update -yqq && \
apt-get install -yqq --no-install-recommends \
nodejs \
nano
COPY Gemfile* /usr/src/app/
WORKDIR /usr/src/app
RUN bundle install
RUN gem install foreman
RUN gem install rake -v 12.3.2
COPY . /usr/src/app/
CMD [ "bin/rails", "s", "-b", "0.0.0.0" ]
.docker-compose.yml
version: '3'
services:
postgres:
image: 'postgres:10.3-alpine'
volumes:
- 'postgres:/var/lib/postgresql/data'
env_file:
- '.env'
redis:
image: 'redis:4.0-alpine'
command: redis-server --requirepass yourpassword
volumes:
- 'redis:/data'
rails:
depends_on:
- 'postgres'
- 'redis'
build: .
ports:
- '3000:3000'
volumes:
- '.:/usr/src/app'
env_file:
- '.env'
volumes:
redis:
postgres:
config/boot.rb
ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
require 'bundler/setup' # Set up gems listed in the Gemfile.
require 'bootsnap/setup' if RUBY_PLATFORM =~ /darwin/
log
rails_1 | /usr/local/lib/ruby/site_ruby/2.6.0/bundler/spec_set.rb:91:in `block in materialize': Could not find rake-12.3.2 in any of the sources (Bundler::GemNotFound)
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/spec_set.rb:85:in `map!'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/spec_set.rb:85:in `materialize'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/definition.rb:170:in `specs'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/definition.rb:237:in `specs_for'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/definition.rb:226:in `requested_specs'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/runtime.rb:108:in `block in definition_method'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/runtime.rb:20:in `setup'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler.rb:107:in `setup'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/bundler/setup.rb:20:in `<top (required)>'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
rails_1 | from /usr/local/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
rails_1 | from /usr/src/app/config/boot.rb:3:in `<top (required)>'
rails_1 | from bin/rails:3:in `require_relative'
rails_1 | from bin/rails:3:in `<main>'

Answer 1

It looks like you are trying to pull down the current latest release of rake. You can remove the version declaration and let it auto resolve in this case.
Any reason this dependency is not in your Gemfile? Also, the rails app you are starting will include a dependency to rake. You should not need to install rake.