An example for how to run Synapse in Docker (not encouraged)

Dockerfile

FROM ubuntu:trusty

# Prep
RUN echo "deb http://archive.ubuntu.com/ubuntu/ trusty main restricted" > /etc/apt/sources.list
RUN echo "deb-src http://archive.ubuntu.com/ubuntu/ trusty main restricted" >> /etc/apt/sources.list
RUN echo "deb http://archive.ubuntu.com/ubuntu/ trusty-updates main restricted" >> /etc/apt/sources.list
RUN echo "deb-src http://archive.ubuntu.com/ubuntu/ trusty-updates main restricted" >> /etc/apt/sources.list
RUN echo "deb http://archive.ubuntu.com/ubuntu/ trusty universe" >> /etc/apt/sources.list
RUN echo "deb http://archive.ubuntu.com/ubuntu/ trusty-updates universe" >> /etc/apt/sources.list
RUN echo "deb http://archive.ubuntu.com/ubuntu trusty-backports main restricted universe multiverse" >> /etc/apt/sources.list
RUN apt-get update
RUN apt-get install -y software-properties-common && add-apt-repository -y ppa:vbernat/haproxy-1.6

RUN apt-get update
RUN apt-get install -y git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev zlib1g libyaml-dev libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison libcurl4-openssl-dev iptables python-pip wget htop psmisc
ENV DEBIAN_FRONTEND noninteractive

#Install OpenSSL
WORKDIR /opt
RUN wget https://www.openssl.org/source/latest.tar.gz && tar xfv latest.tar.gz && rm -rf latest.tar.gz
RUN mv openssl-* openssl
WORKDIR /opt/openssl
RUN ./config && make depend && make && make install
#Link openssl
RUN ln -sf /usr/local/ssl/bin/openssl `which openssl`

# Install RUBY
WORKDIR /tmp
RUN apt-get install -y libffi-dev
RUN wget http://cache.ruby-lang.org/pub/ruby/2.2/ruby-2.2.3.tar.gz
RUN tar xzfv ruby-2.2.3.tar.gz
WORKDIR /tmp/ruby-2.2.3
ENV RUBY_CONFIGURE_OPTS --with-readline-dir=/usr/lib/x86_64-linux-gnu/libreadline.so
RUN ./configure
RUN make
RUN make install
RUN echo "gem: --no-ri --no-rdoc" > ~/.gemrc

# Install Synapse (fr DB)
#RUN gem install synapse
RUN gem install specific_install
RUN gem specific_install -l https://github.com/airbnb/synapse.git

# Install Supervisor
RUN apt-get install -y supervisor
RUN mkdir -p /var/log/supervisor
WORKDIR /opt
# Set up the config for Supervisor
ADD supervisord.conf /etc/supervisor/

# Add Synapse Config
ADD synapse.conf.json /etc/synapse.conf.json

# Install HAProxy
RUN apt-get install -y haproxy
RUN mkdir /var/haproxy

EXPOSE 3212

ENTRYPOINT ["/usr/bin/supervisord"]
CMD ["-c", "/etc/supervisor/supervisord.conf"]

proper_restart.txt

root@00fab8dceae8:/opt# ps axuf
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root        28  1.0  0.0  18144  3120 ?        Ss   21:09   0:00 /bin/bash
root        41  0.0  0.0  15568  2208 ?        R+   21:09   0:00  \_ ps axuf
root         1  0.1  0.1  52120 16704 ?        Ss   21:08   0:00 /usr/bin/python /usr/bin/supervisord -c /etc/supervisor/superv
root         8  0.2  0.0 485848 16116 ?        Sl   21:08   0:00 /usr/local/bin/ruby /usr/local/bin/synapse -c /etc/synapse.con
root        20  0.0  0.0   4332  1280 ?        S    21:08   0:00 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg 
root        26  0.0  0.0  28752  5056 ?        S    21:08   0:00  \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/hapr
root        27  0.0  0.0  28752  3084 ?        Ss   21:08   0:00      \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/
root@00fab8dceae8:/opt# ps axuf
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root        28  0.0  0.0  18144  3280 ?        Ss   21:09   0:00 /bin/bash
root        47  0.0  0.0  15568  2092 ?        R+   21:09   0:00  \_ ps axuf
root         1  0.1  0.1  52120 16704 ?        Ss   21:08   0:00 /usr/bin/python /usr/bin/supervisord -c /etc/supervisor/superv
root         8  0.1  0.0 485848 16304 ?        Sl   21:08   0:00 /usr/local/bin/ruby /usr/local/bin/synapse -c /etc/synapse.con
root        20  0.0  0.0   4332  1444 ?        S    21:08   0:00 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg 
root        26  0.0  0.0  28752  5056 ?        S    21:08   0:00  \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/hapr
root        27  0.0  0.0  28752  3084 ?        Ss   21:08   0:00  |   \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/
root        45  0.0  0.0  28752  5216 ?        S    21:09   0:00  \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/hapr
root        46  0.0  0.0  28752   904 ?        Ss   21:09   0:00      \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/
root@00fab8dceae8:/opt# ps axuf
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root        28  0.0  0.0  18144  3280 ?        Ss   21:09   0:00 /bin/bash
root        48  0.0  0.0  15568  2164 ?        R+   21:09   0:00  \_ ps axuf
root         1  0.1  0.1  52120 16704 ?        Ss   21:08   0:00 /usr/bin/python /usr/bin/supervisord -c /etc/supervisor/superv
root         8  0.1  0.0 485848 16304 ?        Sl   21:08   0:00 /usr/local/bin/ruby /usr/local/bin/synapse -c /etc/synapse.con
root        20  0.0  0.0   4332  1444 ?        S    21:08   0:00 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg 
root        45  0.0  0.0  28752  5216 ?        S    21:09   0:00  \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/hapr
root        46  0.0  0.0  28752  3088 ?        Ss   21:09   0:00      \_ /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /var/
root@00fab8dceae8:/opt# 

supervisord.conf

; supervisor config file

[unix_http_server]
file=/var/run/supervisor.sock

; the below section must remain in the config file for RPC
; (supervisorctl/web interface) to work, additional interfaces may be
; added by defining them in separate rpcinterface: sections
[rpcinterface:supervisor]
supervisor.rpcinterface_factory = supervisor.rpcinterface:make_main_rpcinterface

[supervisorctl]
serverurl=unix:////var/run/supervisor.sock
username=supervisord

[supervisord]
nodaemon=true
logfile_maxbytes=5000000
logfile_backups=5
logfile=/var/log/supervisor/supervisord.log ; (main log file;default $CWD/supervisord.log)
pidfile=/var/run/supervisord.pid ; (supervisord pidfile;default supervisord.pid)
childlogdir=/var/log/supervisor            ; ('AUTO' child log dir, default $TEMP)

[program:synapse]
process_name=synapse
command=synapse -c /etc/synapse.conf.json
numproces=1
stopasgroup=true
autorestart=unexpected
priority=999
stdout_logfile=/var/log/supervisor/synapse.log
stdout_logfile_maxbytes=5000000
stdout_logfile_backups=5
redirect_stderr=true
stopsignal=QUIT

[program:haproxy]
process_name=haproxy
command=/usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /var/haproxy/haproxy.pid
numprocs=1
stopasgroup=false
priority=101
autostart=true
autorestart=true
stdout_logfile=/var/log/supervisor/haproxy.log
stdout_logfile_maxbytes=5000000
stdout_logfile_backups=5
redirect_stderr=true
stopsignal=TERM

synapse.conf.json

{
  "services": {
    "zk_service": {
      "default_servers": [],
      "use_previous_backends": false,
      "discovery": {
        "method": "zookeeper",
        "path": "/services/zk_service",
        "hosts": [
          "169.254.255.254:2181"
        ]
      },
      "haproxy": {
        "port": 1234,
        "backend_name": "zk_service",
        "listen": [
          "mode http"
        ]
      }
    }
  },
  "haproxy": {
    "reload_command": "/bin/kill -USR2 $(pgrep haproxy-systemd)",
    "config_file_path": "/etc/haproxy/haproxy.cfg",
    "socket_file_path": "/tmp/haproxy.sock",
    "global": [
      "daemon",
      "maxconn 4096",
      "stats   socket /tmp/haproxy.sock mode 666 level admin"
    ],
    "defaults": [
      "log      global",
      "option   dontlognull",
      "maxconn  2000",
      "retries  3",
      "timeout  connect 5s",
      "timeout  client  3s",
      "timeout  server  3s",
      "option   redispatch",
      "balance  roundrobin"
    ],
    "extra_sections": {
      "listen stats": [
        "bind :3212",
        "mode http",
        "stats enable",
        "stats uri /",
        "stats refresh 5s"
      ]
    }
  },
  "file_output": {
    "output_directory": "/tmp/synapse"
  }
}