connect-services.py

#!/usr/bin/env python

import os
import subprocess
import sys
import yaml

stack = yaml.load(open(sys.argv[1]))

ports = yaml.load(open("ports.yml"))

project_name = os.path.basename(os.path.realpath("."))

ambassadors = []

service_instances = {}

# Generate container names for all instances
for service_name in stack:
    service_instances[service_name] = []
    n = 0
    while True:
        n += 1
        try:
            container_name = "{}_{}_{}".format(project_name, service_name, n)
            subprocess.check_call(
                [ "docker", "inspect", container_name ],
                stdout=-1, stderr=-1
            )
            service_instances[service_name].append(container_name)
        except subprocess.CalledProcessError:
            break

for service_name, service in stack.items():
    extra_hosts = service.get("extra_hosts", {})
    for link_name, link_addr in extra_hosts.items():
        if link_name not in ports:
            print("# Skipping link {} in service {} "
                  "(no port mapping defined). "
                  "Your code will probably break."
                  .format(link, service_name))
            continue
        port = str(ports[link_name])
        endpoints = []
        for container_name in service_instances[link_name]:
            endpoint = subprocess.check_output(
                ["docker", "port", container_name, port]
            )
            endpoints.append(endpoint.strip())
        for container_name in service_instances[service_name]:
            ambassador = {}
            ambassador["image"] = "jpetazzo/hamba"
            ambassador["net"] = "container:"+container_name
            command = "{}:{}".format(link_addr, port)
            for endpoint in endpoints:
                command = command + " {} {}".format(*endpoint.split(':'))
            ambassador["command"] = command
            n = len(ambassadors)
            ambassador["name"] = "amba{}".format(n)
            ambassadors.append(ambassador)

for service_name, service in stack.items():
    for container_name in service_instances[service_name]:
        print("docker exec {} sh -c 'sed /^127.127/d /etc/hosts >/tmp/hosts && cat /tmp/hosts >/etc/hosts && rm /tmp/hosts'"
              .format(container_name))
        extra_hosts = service.get("extra_hosts", {})
        for link_name, link_addr in extra_hosts.items():
            print("docker exec {} sh -c 'echo {} {} >> /etc/hosts'"
                  .format(container_name, link_addr, link_name))

for amba in ambassadors:
    print("docker run -d --name {name} --net {net} {image} {command}".format(**amba))