Docker Rails app fails to be served - curl: (56) R

Question

I build a Rails app container with the following Dockerfile:

$ cat Dockerfile
FROM ruby:2.2

MAINTAINER Luca G. Soave <[e-mail]>

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
CMD ["rails", "server"]

the build succeed:

$ docker build -t querier .
Sending build context to Docker daemon 46.75 MB
Sending build context to Docker daemon 
...
Step 10 : CMD rails server
 ---> Running in 8eb62f8a579a
 ---> 65eee929d518
Removing intermediate container 8eb62f8a579a
Successfully built 65eee929d518

the container is running:

$ docker logs -f 89ff3bb8c584
=> Booting WEBrick
=> Rails 4.2.0 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2015-01-06 19:56:56] INFO  WEBrick 1.3.1
[2015-01-06 19:56:56] INFO  ruby 2.2.0 (2014-12-25) [x86_64-linux]
[2015-01-06 19:56:56] INFO  WEBrick::HTTPServer#start: pid=1 port=3000

and it's exporting 3000/tcp port:

$ docker ps -al
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS                    NAMES
89ff3bb8c584        querier:latest      "rails server"      16 minutes ago      Up 16 minutes       0.0.0.0:3000->3000/tcp   gloomy_babbage   

but the server is not reachable 'internally' or 'externally' Docker:

$ curl 0.0.0.0:3000
curl: (56) Recv failure: Connection reset by peer
$ curl 172.17.0.24:3000
curl: (7) Failed to connect to 172.17.0.24 port 3000: Connection refused

but everything seems ok:

$ docker inspect --format '{{ .NetworkSettings.IPAddress }}' 89ff3bb8c584
172.17.0.24
$ netstat -r
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
default         10.36.32.1      0.0.0.0         UG        0 0          0 wlan0
10.0.3.0        *               255.255.255.0   U         0 0          0 lxcbr0
10.36.32.0      *               255.255.248.0   U         0 0          0 wlan0
172.17.0.0      *               255.255.0.0     U         0 0          0 docker0

$ ping 0.0.0.0
PING 0.0.0.0 (127.0.0.1) 56(84) bytes of data.
64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.069 ms
64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.061 ms
64 bytes from 127.0.0.1: icmp_seq=3 ttl=64 time=0.069 ms
^C
--- 0.0.0.0 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1998ms
rtt min/avg/max/mdev = 0.061/0.066/0.069/0.007 ms

$ ping 172.17.0.24
PING 172.17.0.24 (172.17.0.24) 56(84) bytes of data.
64 bytes from 172.17.0.24: icmp_seq=1 ttl=64 time=0.085 ms
64 bytes from 172.17.0.24: icmp_seq=2 ttl=64 time=0.107 ms
64 bytes from 172.17.0.24: icmp_seq=3 ttl=64 time=0.076 ms
^C

I tried also in the browser but nothing. The host sistem is:

$ docker -v
Docker version 1.4.1, build 5bc2ff8
$ uname -a 
Linux basenode 3.11.0-18-generic #32-Ubuntu SMP Tue Feb 18 21:11:14 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Any idea?

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.