What is it for?

Dynamic upstream will help you to send your service, task and node list to service url. For example;

Let's say you added a new service to your docker swarm (and you are using multi-host). Overlay network won't work always as you expected. It will make you crazy 🙂 (We have been there!). So old techs and images won't work too...

Good news!

You can get information when a service added, updated etc. This service will automatically send you a http request like this;

{
  "nodes": [
    {
      "Id": "xvvpn493yqrvtove74o33o9sf",
      "Name": "linuxkit-025000000001",
      "Ip": "192.168.65.3"
    }
  ],
  "services": [
    {
      "Name": "nginx",
      "Ports": [
        {
          "TargetPort": 80,
          "PublishedPort": 9099
        }
      ],
      "Nodes": [
        "xvvpn493yqrvtove74o33o9sf"
      ],
      "Labels": {
        "mono.upstream.mode": "least_conn"
      }
    },
    {
      "Name": "redis",
      "Ports": [
        {
          "TargetPort": 6397,
          "PublishedPort": 2222
        }
      ],
      "Nodes": [
        "xvvpn493yqrvtove74o33o9sf"
      ],
      "Labels": {}
    }
  ]
}

Your can use following environment variables;

Variable	Default	Description
MONO_SERVICE	null	The service url like "http://mylb.example.com/update"
MONO_SECRET	null	Use it and secure your endpoint. This will sent to your server with header "X-SECRET"
MONO_PREIOD	3	Seconds - will check your services every 3 seconds.

and a command like --always (Which will help you to ignore caching and send always updated version of your services). Also --debug will show you the request body.

So with this data, you can use it with template scripts and update your load balancer upstream (like nginx).

We are using volume bind for accessing your services.

So how to run?

docker run -d \
    --name=dynamic-upstream \
    -e MONO_SERVICE=http://yourwebservice/ \
    -e MONO_SECRET=YOUR_ULTIMATE_SECRET_KEY \
    -e MONO_PERIOD=3 \
    --volume=/var/run/docker.sock:/var/run/docker.sock \
    monofor/dynamic-upstream:latest

** You can also run it as a service by the way.

Run with always command;

docker run -d \
    --name=dynamic-upstream \
    --volume=/var/run/docker.sock:/var/run/docker.sock \
    monofor/dynamic-upstream:latest --always

We will also publish combined version with nginx config.