Haproxy + docker-gen hostname routing

!haproxy+docker-gen.md

What is this?

This gist includes config for haproxy + docker-gen system with routing http requests to different containers based on hostname label.

pre requirements

• docker-engine
• docker-gen ( https://github.com/jwilder/docker-gen )
• haproxy ( current setup uses debian packaged service )

Usage

• put haproxy.tmpl to /etc/haproxy/haproxy.tmpl and docker-gen.cfg to /etc/docker-gen.cfg
• run docker-gen -config /etc/docker-gen.cfg to start the system
• run containers with hostname label e.g. docker run --label hostname=foo.example.com nginx

Integrating with debian services

• put docker-gen.service to /etc/systemd/system/docker-gen.service
• enable service with systemctl enable docker-gen
• start docker-gen service with service docker-gen start

docker-gen.cfg

[[config]]
template = "/etc/haproxy/haproxy.tmpl"
dest = "/etc/haproxy/haproxy.cfg"
IncludeStopped = true
onlyexposed = true
notifycmd = "service haproxy reload"
watch = true
wait = "2s:10s"

docker-gen.service

[Unit]
Description=A file generator that renders templates using Docker Container meta-data.
Documentation=https://github.com/jwilder/docker-gen
After=network.target docker.socket
Requires=docker.socket

[Service]
ExecStart=/usr/local/bin/docker-gen -config /etc/docker-gen.cfg

[Install]
WantedBy=multi-user.target

haproxy.tmpl

global
    log /dev/log    local0
    log /dev/log    local1 notice
    chroot /var/lib/haproxy
    user haproxy
    group haproxy
    daemon
    #maxconn 256

defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
    contimeout 5000
    clitimeout 5000
    srvtimeout 15000
    balance leastconn
    errorfile 400 /etc/haproxy/errors/400.http
    errorfile 403 /etc/haproxy/errors/403.http
    errorfile 408 /etc/haproxy/errors/408.http
    errorfile 500 /etc/haproxy/errors/500.http
    errorfile 502 /etc/haproxy/errors/502.http
    errorfile 503 /etc/haproxy/errors/503.http
    errorfile 504 /etc/haproxy/errors/504.http

    option forwardfor header X-Real-IP

{{ $services := groupByLabel $ "hostname" }}
frontend http-in
    bind *:80

    #default_backend failback
    {{ range $host, $containers := $services }}
    {{ $name := replace $host "." "_" -1}}
    acl host_{{ $name }} hdr_dom(host) -i {{ $host }}
    use_backend {{ $name }} if host_{{ $name }}
    {{ end }}

{{ range $host, $containers := $services }}
{{ $name := replace $host "." "_" -1}}
backend {{ $name }}
    #option httpchk /ping.php
    option http-server-close
    {{ range $index, $container := $containers }}
    {{ with $address := index $container.Networks 0 }}
    server server{{ $index }} {{ $address.IP }}:80 check inter 10000 maxconn 50
    {{ end }}
    {{ end }}
{{ end }}


backend failback