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@haizaar

haizaar/nginx-ip-watch

Last active Apr 24, 2016
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Reverse proxy to Kubernetes cluster NodePort through nginx
#!/usr/bin/env python
import os
import subprocess
import argparse
import json
from oauth2client.client import GoogleCredentials
from googleapiclient import discovery
nginx_conf = """
upstream %(name)s {
%(servers)s
}
server {
listen %(listen_ip)s:%(listen_port)s;
location / {
proxy_pass http://%(name)s;
}
}
"""
nginx_conf_dir = "/etc/nginx/sites-enabled"
def main():
parser = argparse.ArgumentParser("Watch GKE node IPs for changes")
parser.add_argument("-p", "--project", required=True, help="Project to list instances for")
parser.add_argument("-z", "--zones", required=True, action="append", help="Zones to list instances for")
parser.add_argument("name", help="Meaningful name of your forwarding rule")
parser.add_argument("gke_prefix", metavar="gke-prefix", help="GKE node prefix to monitor and forward to")
parser.add_argument("listen_ip", metavar="listen-ip", help="IP listen on")
parser.add_argument("listen_port", metavar="listen-port", type=int, help="Port to listen on")
parser.add_argument("target_port", metavar="target-port", type=int, help="IP listen on")
args = parser.parse_args()
credentials = GoogleCredentials.get_application_default()
compute = discovery.build('compute', 'v1', credentials=credentials)
instances = []
for zone in args.zones:
instances.extend(compute.instances().list(project=args.project, zone=zone).execute()["items"])
ips = []
for ins in instances:
if not ins["name"].startswith(args.gke_prefix):
continue
ips.extend( (nic["networkIP"] for nic in ins["networkInterfaces"]) )
ips = sorted(ips)
args.servers = "\n".join((" server %s:%s;" % (ip, args.target_port) for ip in ips))
new_conf = nginx_conf % args.__dict__
conf_fn = os.path.join(nginx_conf_dir, args.name)
try:
old_conf = open(conf_fn).read()
except IOError:
old_conf = ""
if old_conf != new_conf:
with open(conf_fn, "wt") as f:
f.write(new_conf)
subprocess.check_call("service nginx reload", shell=True)
if __name__ == "__main__":
main()
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