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Network Ports

Web​

When deploying a web application, the way to have the web traffic served through disco's reverse proxy is to specify the port in your disco.json.

{
    "version": "1.0",
    "services": {
        "web": {
            "port": 8080,
            "command": "./bin/serve.sh",
        }
    }
}

That way, requests come in to your server on port 443 (for https) and disco's reverse proxy will forward the request to your app on port 8080.

Also, note that the name web for the service is important. disco will use that service to expose to the internet. You can't specify port on a service not named web.

Internal Communication Between Services​

When a disco.json file contains many services, they can see each other by their names. All ports are accessible in this internal network.

For example:

In a project that has a disco.json file that looks like this:

{
    "version": "1.0",
    "services": {
        "web": {
            "command": "./bin/serve.sh",
            "port": 8080
        },
        "worker": {
            "command": "python worker.py"
        }
    }
}

The service worker could make this call

import requests

response = requests.get("http://web:8080/")

Note the http scheme (not https and the port :8080 in "http://web:8080/". The network used is encrypted (no need for HTTPS), and since it's not going through the reverse proxy, the port that is exposed on the container directly is used.

All ports are exposed in this private network. For example, we could have an internal API running like this:

{
    "version": "1.0",
    "services": {
        "web": {
            "command": "./bin/serve.sh",
            "port": 8080
        },
        "internalapi": {
            "command": "./bin/serve-internal-api.sh"
        }
    }
}

web could query internalapi on the ports it exposes (like 80, or 8888, etc.), without having to specify them in disco.json, because they're not exposed to the internet. If your program is listening on a port, the other services of the same project can communicate with it. No special trick needed on your side.

web could also expose other ports to be made available internally without exposing them to the internet. Only the port of web that is defined in port is exposed to the internet (defaulting to 8000 when none is specified).

Publishing Ports Extenally​

In the case where you would like to expose a port externally, bypassing the reverse proxy, you can it like so:

{
    "version": "1.0",
    "services": {
        "receiver": {
            "command": "./bin/receiver.sh",
            "publishedPorts": [{
                "publishedAs": 12000,
                "fromContainerPort": 11000,
                "protocol": "udp"
            }]
        }
    }
}

In this case, the container's port 11000 will be exposed on the server directly as port 12000. Also, the protocol defined is udp, or tcp.

Since it does not go through the reverse proxy, disco will not provide a TLS certificate for HTTPS.