Proposal: local-run to run multiple functions in a docker network

Description

Proposal: local-run to run multiple functions in a docker network

Today, if you have two functions that are inter-related, and may even talk to each other, you will need to deploy that to Kubernetes.

faas-cli local-run is an easy way to test out functions without having a license installed or a Kubernetes cluster - just by using Docker alone.

A docker network, plus some Go routines could enable local-run to run multiple functions at once, and allow them to communicate.

Example YAML file:

version: 1.0
provider:
  name: openfaas
  gateway: http://127.0.0.1:8080

functions:
  test:
    lang: golang-middleware
    handler: ./test
    image: test:latest

  test2:
    lang: golang-middleware
    handler: ./test2
    image: test2:latest

For multiple functions - local-run would run all functions in the file.

You could then filter back down with the --filter flag i.e. --filter test2

@welteki suggested a basic / dummy gateway that is also run as a container, which can avoid having to stub out or replace calls from functions to the http://gateway.openfaas:8080 etc

Start at the faas-cli local-run command and review how it currently starts a single function with Docker. No file or test is named; the proposal's completion criteria are running multiple functions together, supporting --filter, and allowing communication over a Docker network, potentially through a containerized gateway.