Docker Rails app fails to be served - curl: (56) Recv failure: Connection reset by peer

Question

I build a Rails app container with the following Dockerfile:

$ cat Dockerfile
FROM ruby:2.2

MAINTAINER Luca G. Soave 

RUN apt-g         


        

Answer 1

I just flagged Mykola Gurov answer because is the right 'cause' of my issue, anyway I'd also like to add the solution I implemented to work around that cause, just for tracking pourpose.

I modified config/boot.rb by adding default option:

$ cat config/boot.rb
# Set up gems listed in the Gemfile.
ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)

require 'bundler/setup' if File.exists?(ENV['BUNDLE_GEMFILE'])

########  added lines  ########
require 'rails/commands/server' 

module Rails
  class Server
    alias :default_options_alias :default_options
    def default_options
      default_options_alias.merge!(:Host => '0.0.0.0')
    end
  end
end
###############################

If you don't want modify config/boot.rb, another solution could be forcing Dockerfile to bind 0.0.0.0 host as an ENTRYPOINT/CMD parameter:

$ cat Dockerfile
FROM ruby:2.2

RUN apt-get update && apt-get install -y nodejs --no-install-recommends && rm -rf /var/lib/apt/lists/*
RUN apt-get update && apt-get install -y mysql-client postgresql-client sqlite3 --no-install-recommends && rm -rf /var/lib/apt/lists/*

RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

COPY . /usr/src/app/
RUN bundle install

EXPOSE 3000
ENTRYPOINT ["rails", "server", "-b", "0.0.0.0"]

Answer 2

Rails server documentation states that the server by default binds to localhost, and this usually prevents dockerized application to accept connections. Try changing it to 0.0.0.0.