Use the Pod FQDN to generate the right SRV record

This simplifies the Kube configuration by relying on the information
that already exists inside the Pod. The FQDN format is stable and
well-documented.

Author: kocolosk

mem3_helper.py

@@ -2,16 +2,16 @@
 # called "couchdb" and feeds those as `couchdb@HOSTNAME` nodes to mem3.
 
 import json
-import os
 import requests
 import time
 import dns.resolver
+import socket
 
 def discover_peers_dns(retries=5):
-    # Assumes <namespace>.svc.cluster.local is in the DNS search space ...
-    resource = '_couchdb._tcp.{0}'.format(
-        os.environ.get("COUCHDB_SERVICE", "couchdb")
-    )
+    # Drop our Pod's unique identity and replace with '_couchdb._tcp'
+    # to form the name of the SRV record
+    resource = '.'.join(['_couchdb', '_tcp'] + socket.getfqdn().split('.')[1:])
+    print ('SRV record', resource)
     if retries > 0:
         try:
             answers = dns.resolver.query(resource, 'SRV')
@@ -53,5 +53,4 @@ def sleep_forever():
         time.sleep(5)
 
 if __name__ == '__main__':
-    print(os.environ)
     discover_peers_dns()