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Last pushed: 2 years ago
Short Description
The official QUAD HAProxy image.
Full Description


Dynamic haproxy configuration using consul packed into a Docker container that weighs 24MB.

Table of Contents


This project combines Alpine Linux, consul template, and haproxy to create a proxy that forwards traffic to apps registered in consul.

How it works

First, you must set up a wildcard dns (using something like CloudFlare or This means that if your domain is, any request to a <name> will resolve to the IP of your haproxy container.

Inside the haproxy container, a header match is used to map <application> to the service registered in consul under application.



Start the container as follows:

docker run --net=host --name=haproxy -d asteris/haproxy-consul

alternative way not sharing network stack with host:

docker run -d --name haproxy -p 80:80 -p 443:443 -e CONSUL_CONNECT= asteris/haproxy-consul

Now that it is set up, connect to an app:

curl -L

Or if you do not have a wildcard DNS:

curl -L


haproxy-consul can run in two different modes: forwarding either consul services (the default) or Marathon apps. This behavior is controlled by the HAPROXY_MODE variable, which should be set to consul or marathon.

Reload configuration

It's possible to reload the HA proxy configuration without restarting the container itself. docker exec -it <container_id> bash

consul Configuration

When HAPROXY_MODE is set to consul, haproxy-consul uses consul service names to set subdomains. No other configuration is required.

Marathon Configuration

When HAPROXY_MODE is set to marathon, haproxy-consul assumes that there will be app information in the marathon prefix of the Consul KV store. It was written to work with the information provided by marathon-consul.

By default, haproxy will forward all Marathon-assigned ports. So if you specify that your application should own port 10000 in the "ports" member of the app JSON, haproxy will open port 10000 to direct traffic to your app. This works with auto-assigned ports (ports set to 0), as well. This is all automatic, you don't need to think about it other than to pull the ports from Marathon.

However, if you want HTTP load balancing using the host header, you need a specify the following labels on your app:

    "id": "hello-rails",
    "cmd": "cd hello && bundle install && bundle exec unicorn -p $PORT",
    "mem": 100,
    "cpus": 1.0,
    "instances": 1,
    "uris": [
    "env": {
        "RAILS_ENV": "production"
    "ports": [10000],
    "labels": {
        "HAPROXY_HTTP": "true",
        "HTTP_PORT_IDX_0_NAME": "hello_rails",

In this example (available at examples/rails.json), the hello-rails application is assigned port 10000. This is different from the service or host port of the app; it is a global value that Marathon tracks. This means that haproxy-consul will forward all TCP traffic to port 10000 to the app workers.

When HAPROXY_HTTP is set to true and HTTP_PORT_IDX_0_NAME is set to a DNS-valid name Haproxy will forward all HTTP traffic with the host header (the name specified plus HAPROXY_DOMAIN) to the app workers. This extends to as many ports as you'd care to give it in the form HTTP_PORT_IDX_{port_number}_NAME.

This particular app results in something like the following haproxy configuration:

    maxconn 256

    mode tcp
    timeout connect 5000ms
    timeout client 50000ms
    timeout server 50000ms

# HTTP services
frontend www
    mode http
    bind *:80

    # files ACLs
    acl host_hello_rails hdr(host) -i hello_rails.haproxy.service.consul
    use_backend hello_rails_backend if host_hello_rails

# files backends
backend hello_rails_backend
    mode http
    server # TASK_RUNNING

# TCP services
listen hello-rails_10000
    mode tcp
    bind *:10000
    server task_id # TASK_RUNNING

Service registration


Run a registrator to automatically add and remove services. The best option so far is to run gliderlabs/registrator container through the following command.

docker run -d --net host --name registrator -v /var/run/docker.sock:/tmp/docker.sock gliderlabs/registrator consul://

An other way to run it, without net host is:

docker run -d --name registrator -v /var/run/docker.sock:/tmp/docker.sock gliderlabs/registrator consul://

Naming services

The service can be declared through the environment variables SERVICE_NAME and SERVICE_TAGS.

The SERVICE_NAME or SERVICE_<port>_NAME is the actual name you want to give to the service. It will be the subdomain of your requests: <SERVICE_NAME>.domain.tld.

The domain can be specified using SERVICE_TAGS using the followind syntax: <domain>_<tld>. Note the _ (underscore) instead of a . (dot), this approach was used because consul forbids the presence of dots in a service name or tag. If no SERVICE_TAGS is specified, the service will be available on all domains.

Here is an complete example:

docker run -p 80 -e SERVICE_NAME=www -e SERVICE_TAGS=example_com,example_net webserver

This will make the webserver's 80 port accessible through request to or Also note that requests to or will be redirected (302 permanent redirect) to the corresponding www subdomain.


If you want to override the config and template files, mount a volume and set the CONSUL_CONFIG environment variable before launch. In docker this can be accomplished with the -e option:

docker run -v /host/config:/my_config -e CONSUL_CONFIG=/my_config -net=host --name=haproxy -d asteris/haproxy-consul

If you need to have a root CA added so you can connect to Consul over SSL, mount a directory containing your root CA at /usr/local/share/ca-certificates/.

Configure using the following environment variables:

Variable Description Default
HAPROXY_DOMAIN The domain to match against haproxy.service.consul (for app.haproxy.service.consul).
HAPROXY_MODE forward consul service or Marathon apps consul (marathon also available, as described above)
HAPROXY_USESSL Enable the SSL frontend (see below) false
HAPROXY_STATS Enable Statistics UI on port 1936 (see below) false
HAPROXY_STATS_TITLE Change Statistics Title (see below) false
HAPROXY_STATS_URI Change Statistics URI (see below) false

consul-template variables:

Variable Description Default
CONSUL_TEMPLATE Location of consul-template bin /usr/local/bin/consul-template
CONSUL_CONNECT The consul connection consul.service.consul:8500
CONSUL_CONFIG File/directory for consul-template config /consul-template/config.d
CONSUL_LOGLEVEL Valid values are "debug", "info", "warn", and "err". debug
CONSUL_TOKEN The Consul API token

SSL Termination

If you wish to configure HAproxy to terminate incoming SSL connections, you must set the environment variable HAPROXY_USESSL=true, and mount your SSL certificate at /certs/ - this folder should contain all your certificates, each should contain both the SSL certificate and the private key to use (with no passphrase), in PEM format. You should also include any intermediate certificates in this bundle.

For example:

docker run -v /etc/ssl/ --net=host --name=haproxy asteris/haproxy-consul

SSL termination is currently only available in 'consul' mode.


Released under an Apache 2.0 License. See LICENSE

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