From 3b0ea900cd92762f39c2f656ae2d20e7abf20efe Mon Sep 17 00:00:00 2001
From: Christopher Winslett <chris@compose.io>
Date: Wed, 13 May 2015 16:37:14 -0700
Subject: [PATCH] followers without a leader based on feedback from @CyberDem0n
 and closes #3

---
 governor.py           |  2 +-
 helpers/ha.py         |  1 +
 helpers/postgresql.py | 19 +++++++++++++++----
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/governor.py b/governor.py
index 31081f07..c3847bd2 100755
--- a/governor.py
+++ b/governor.py
@@ -55,7 +55,7 @@ if postgresql.data_directory_empty():
             else:
                 time.sleep(5)
 else:
-    postgresql.write_recovery_conf({"address": "postgres://169.0.0.1:5432"})
+    postgresql.follow_no_leader()
     postgresql.start()
 
 while True:
diff --git a/helpers/ha.py b/helpers/ha.py
index 80736420..bd770524 100644
--- a/helpers/ha.py
+++ b/helpers/ha.py
@@ -59,6 +59,7 @@ class Ha:
                             self.state_handler.demote(self.fetch_current_leader())
                             return "demoting self because i am not the healthiest node"
                         elif self.fetch_current_leader() is None:
+                            self.state_handler.follow_no_leader()
                             return "waiting on leader to be elected because i am not the healthiest node"
                         else:
                             self.state_handler.follow_the_leader(self.fetch_current_leader())
diff --git a/helpers/postgresql.py b/helpers/postgresql.py
index 387ff19a..f6bbcd69 100644
--- a/helpers/postgresql.py
+++ b/helpers/postgresql.py
@@ -158,15 +158,18 @@ class Postgresql:
         f.close()
 
     def write_recovery_conf(self, leader_hash):
-        leader = urlparse(leader_hash["address"])
-
         f = open("%s/recovery.conf" % self.data_dir, "w")
         f.write("""
 standby_mode = 'on'
 primary_slot_name = '%(recovery_slot)s'
-primary_conninfo = 'user=%(user)s password=%(password)s host=%(hostname)s port=%(port)s sslmode=prefer sslcompression=1'
 recovery_target_timeline = 'latest'
-""" % {"recovery_slot": self.name, "user": leader.username, "password": leader.password, "hostname": leader.hostname, "port": leader.port})
+""" % {"recovery_slot": self.name})
+        if leader_hash is not None:
+            leader = urlparse(leader_hash["address"])
+            f.write("""
+primary_conninfo = 'user=%(user)s password=%(password)s host=%(hostname)s port=%(port)s sslmode=prefer sslcompression=1'
+            """ % {"user": leader.username, "password": leader.password, "hostname": leader.hostname, "port": leader.port})
+
         if "recovery_conf" in self.config:
             for name, value in self.config["recovery_conf"].iteritems():
                 f.write("%s = '%s'\n" % (name, value))
@@ -179,6 +182,14 @@ recovery_target_timeline = 'latest'
             self.restart()
         return True
 
+    def follow_no_leader(self):
+        print "initing leaderless follower"
+        if os.system("grep primary_conninfo %(data_dir)s/recovery.conf > /dev/null" % {"data_dir": self.data_dir}) == 0:
+            self.write_recovery_conf(None)
+            if self.is_running():
+                self.restart()
+        return True
+
     def promote(self):
         return os.system("pg_ctl promote -w -D %s" % self.data_dir) == 0