auguster / haproxy-consul

Dynamic haproxy configuration using consul

haproxy-consul

Dynamic haproxy configuration using consul packed into a Docker container.

Overview

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 xip.io). This means that if your domain is example.com, any request to a <name>.example.com will resolve to the IP of your haproxy container.

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

Building

docker build -t haproxy .

Service registration

Registrator

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://127.0.0.1:8500

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://172.17.0.1:8500

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 www.example.com or www.example.net. Also note that requests to example.com or example.com will be redirected (302 permanent redirect) to the corresponding www subdomain.

Running

Usage

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=172.17.0.1:8500 asteris/haproxy-consul

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

curl -L http://myapp.mycompany.com

Or if you do not have a wildcard DNS:

curl -L http://myapp.180.19.20.21.xip.io

Modes

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 reload.sh

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": [
        "http://downloads.mesosphere.com/tutorials/RailsHello.tgz"
    ],
    "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:

global
    maxconn 256
    debug

defaults
    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 1.2.3.4:49165 # TASK_RUNNING

# TCP services
listen hello-rails_10000
    mode tcp
    bind *:10000
    server task_id 1.2.3.4:41965 # TASK_RUNNING

Options

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_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/wildcard.example.com.pem:/certs/ssl.crt:ro --net=host --name=haproxy asteris/haproxy-consul

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

License

Released under an Apache 2.0 License. See LICENSE