Initial commit

Dockerfile

@@ -0,0 +1,14 @@
+FROM debian:8.0
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends python3.4 python3-pip \
+    && pip3 install docker-py \
+    && rm -rf /var/lib/apt/lists/*
+
+VOLUME ["/dockerfiles"]
+ENTRYPOINT ["/dockerfiles/entrypoint.sh"]
+
+CMD ["python3"]
+
+
+

hoster.py

@@ -0,0 +1,117 @@
+#!/usr/bin/python3
+from docker import Client
+import argparse
+import shutil
+import signal
+import time
+import sys
+import os
+
+label_name = "hoster.domains"
+enclosing_pattern = "#-----------Docker-Hoster-Domains----------\n"
+hosts_path = "/tmp/hosts"
+hosts = {}
+
+def signal_handler(signal, frame):
+    global hosts
+    hosts = {}
+    update_hosts_file()
+    sys.exit(0)
+
+def main():
+    # register the exit signals
+    signal.signal(signal.SIGINT, signal_handler)
+    signal.signal(signal.SIGTERM, signal_handler)
+
+    args = parse_args()
+    global hosts_path
+    hosts_path = args.file
+
+    docker = Client(base_url='unix://%s'%args.socket)
+    events = docker.events(decode=True)
+    #get running containers
+    for c in docker.containers(quiet=True,all=False):
+        container_id = c["Id"]
+        container = get_container_data(docker, container_id)
+        hosts[container_id] = container
+
+    update_hosts_file()
+
+    #listen for events to keep the hosts file updated
+    for e in events:
+
+        if e["status"]=="start":
+            container_id = e["id"]
+            container = get_container_data(docker, container_id)
+            hosts[container_id] = container
+            update_hosts_file()
+
+        if e["status"]=="stop":
+            container_id = e["id"]
+            hosts.pop(container_id)
+            update_hosts_file()
+
+
+def get_container_data(docker, container_id):
+    #extract all the info with the docker api
+    info = docker.inspect_container(container_id)
+    container_ip = info["NetworkSettings"]["IPAddress"]
+    container_name = info["Name"].strip("/")
+    labels = info["Config"]["Labels"]
+    domains = set()
+    if label_name in labels:
+        domains = domains.union([d.strip() for d in labels[label_name].split()])
+
+    domains.add("%s.local"%container_name)
+
+    return { "ip": container_ip, "name": container_name, "domains": domains}
+
+
+def update_hosts_file():
+    if len(hosts)==0:
+        print("Removing all hosts before exit...")
+    else:
+        print("Updating hosts file with:")
+
+    for k,v in hosts.items():
+        print("ip: %s domains: %s"%(v["ip"],v["domains"]))
+
+    #read all the lines of thge original file
+    lines = []
+    with open(hosts_path,"r+") as hosts_file:
+        lines = hosts_file.readlines()
+
+    #remove all the lines after the known pattern
+    for i,line in enumerate(lines):
+        if line==enclosing_pattern:
+            lines = lines[:i]
+            break;
+
+    #remove all the trailing newlines on the line list
+    while lines[-1].strip()=="": lines.pop()
+
+    #append all the domain lines
+    if len(hosts)>0:
+        lines.append("\n\n"+enclosing_pattern)
+        for k,v in hosts.items():
+            lines.append("%s    %s\n"%(v["ip"],"   ".join(v["domains"])))
+        lines.append("#-----Do-not-add-hosts-after-this-line-----\n\n")
+
+    #write it on the auxiliar file
+    aux_file_path = hosts_path+".aux"
+    with open(aux_file_path,"w") as aux_hosts:
+        aux_hosts.writelines(lines)
+
+    #replace etc/hosts with aux file, making it atomic
+    shutil.move(aux_file_path, hosts_path)
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description='Synchronize running docker container IPs with host /etc/hosts file.')
+    parser.add_argument('socket', type=str, nargs="?", default="tmp/docker.sock", help='The docker socket to listen for docker events.')
+    parser.add_argument('file', type=str, nargs="?", default="/tmp/hosts", help='The /etc/hosts file to sync the containers with.')
+    return parser.parse_args()
+
+if __name__ == '__main__':
+    main()
+