Added in a way to register a web server with an Nginx Reverse Proxy.

Author: Josh Gachnang

register-nginx/default.upstream

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+test.com
+test2.com

register-nginx/register-nginx.py

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+#/usr/bin/env python
+
+# This script sits on an Nginx server, and is run by remote Apache/Nginx
+# or app servers to register themselves in a cluster with Nginx. We are using
+# this on EC2, to let web/php servers register with the Nginx load balancer.
+
+# Assumes nginx.conf has an upstream default in the config like so:
+# upstream default { include /etc/nginx/default.upstream; }
+# This file is simply a list of hostnames.
+# You may include other upstream files, in the form:
+# upstream cluster_name { include /etc/nginx/cluster_name.upstream; }
+
+# Usage: python register-nginx.py [-d/--deregister] client_hostname [cluster_name]
+
+# By the way, I know this is UGLY. But it was quick and dirty. Some day, I might
+# fix it.
+
+import sys
+
+DEBUG = False
+
+if DEBUG:
+	file_template = "%s.upstream"	
+else:
+	file_template = "/etc/nginx/%s.upstream"
+
+def register(hostname, cluster="default"):
+	# See if the hostname exists already
+	with open(file_template % cluster) as cluster_file:
+		for line in cluster_file.readlines():
+			if hostname + '\n' == line:
+				print "Host %s already registered with cluster %s" % (hostname, cluster)
+				sys.exit(1)
+	# Append the new hostname to the file
+	with open(file_template % cluster, 'a') as cluster_file:
+		cluster_file.write(hostname + '\n')
+def deregister(hostname, cluster="default"):
+	new_file = []
+	# Read through the file, add all lines that aren't the hostname to a new array 	
+	with open(file_template % cluster, 'r') as cluster_file:
+		lines = cluster_file.readlines()
+		old_file_len = len(lines)
+		for line in lines:
+			print hostname, line
+			if hostname + '\n' != line:
+				new_file.append(line)
+	if len(new_file) == old_file_len:
+		print "Host %s not registered with cluster %s" % (hostname, cluster)
+		sys.exit(2)
+	# Write the array, minus the deregistered hostname, to the file
+	with open(file_template % cluster, 'w') as cluster_file:
+		for line in new_file:
+			cluster_file.write(line)
+
+if __name__ == "__main__":
+	# arv[0] == appname, argv[1] == first arg, etc If len == 2: default register, 3: deregister OR other cluster. 4: deregister other cluster
+	if len(sys.argv) == 2:
+		register(sys.argv[1])
+	elif len(sys.argv) == 3:
+		if sys.argv[1] == '-d' or sys.argv[1] == '--deregister':
+			deregister(sys.argv[2])
+		else:
+			register(sys.argv[1], sys.argv[2])
+	elif len(sys.argv) == 4:
+		deregister(sys.argv[2], sys.argv[3])
+	else:
+		print "usage:"
+		print "python register-nginx.py [-d/--deregister] hostname [cluster_name]"

register-nginx/test.upstream

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+test.com
+test2.com