dcos-proxy

DCOS Frontend Proxy

This is a reverse load balancer based on Nginx that is designed to run on the public slave nodes of a Mesosphere DCOS cluster.

There is a sample json file for running the balancer, which you can use with:

dcos marathon app add frontend-balancer.json

The refresh job runs every 10 seconds, looking at all your apps with a VIRTUAL_HOST label, and creating a proxy entry directed to the first port supplied.

{
    "constraints": [["hostname", "UNIQUE"]],
    "container": {
        "type": "DOCKER",
        "docker": {
            "image": "registry"
        }
    },
    "labels": {
        "VIRTUAL_HOST": "registry.your.domain.here"
    },
    "id": "registry",
    "cpus": 1,
    "mem": 256,
    "instances": 2,
    "ports": [5000]
}

Important Notes:

DCOS provisions by-default with Elastic Load Balancers configured with a HTTP:80/ health check. The nginx configuration in this proxy service responds with 503 to such requests (as they do not match any vhost record), and will result in all public slaves being reported as unhealthy.

Solutions for this include: - Change your Public Slave ELB to a TCP:80 health check - Add a server block to the nginx.conf for a route such as /elb-status which responds with 200 OK