Limit voting members to the those residing within the primary region (#193)

* Limit voting members to the those residing in the primary region

* Require in-region quorum

* Update docs to reflect changes

* Typo

Author: davissp14

README.md

@@ -15,9 +15,7 @@ fly pg create --name <app-name> --initial-cluster-size 3 --region ord --flex
 ```
 
 ## High Availability
-For HA, it's recommended that you run at least 3 members.
-
-Automatic failovers will only consider members residing within your primary region.  The primary region is represented as an environment variable defined within the `fly.toml` file.  That being said, if you're running a 3 member setup at least 2 of your members should reside within your primary region.
+For HA, it's recommended that you run at least 3 members within your primary region. Automatic failovers will only consider members residing within your primary region. The primary region is represented as an environment variable defined within the `fly.toml` file.
 
 ## Horizontal scaling
 Use the clone command to scale up your cluster.

docs/fencing.md

@@ -1,7 +1,7 @@
 # Fencing
 
 ## How do we verify the real primary?
-We start out evaluating the cluster state by checking each registered standby for connectivity and asking who their primary is.
+We start out by evaluating the cluster state by checking each registered standby within the primary region for connectivity and asking who their primary is.
 
 The "clusters state" is represented across a few different dimensions:
 
@@ -24,7 +24,7 @@ map[string]int{
 }
 ```
 
-The real primary is resolvable so long as the majority of members can agree on who it is. Quorum being defined as `total_members / 2 + 1`.
+The real primary is resolvable so long as the majority of members can agree on who it is. Quorum being defined as `total_members_in_region / 2 + 1`.
 
 **Note: When the primary being evaluated meets quorum, it will still be fenced in the event a conflict is found. This is to protect against a possible race condition where an old primary comes back up in the middle of an active failover.**
 
@@ -45,11 +45,11 @@ The cluster will be made read-only and the `zombie.lock` file will be created wi
 
 ## Monitoring cluster state
 
-In order to mitigate possible split-brain scenarios, it's important that cluster state is evaluated regularly and when specific events/actions take place.  
+In order to mitigate possible split-brain scenarios, it's important that cluster state is evaluated regularly and when specific events/actions take place.
 
 ### On boot
 This is to ensure the booting primary is not a primary coming back from the dead.
-  
+
 ### During standby connect/reconnect/disconnect events
 There are a myriad of reasons why a standby might disconnect, but we have to assume the possibility of a network partition.  In either case, if quorum is lost, the primary will be fenced.
 
@@ -60,7 +60,7 @@ Cluster state is monitored in the background at regular intervals. This acts as
 ## Split-brain detection window
 **This pertains to v0.0.36+**
 
-When a network partition is initiated, the following steps are performed: 
+When a network partition is initiated, the following steps are performed:
 
 1. Repmgr will attempt to ping registered members with a 5s connect timeout.
 2. Repmgr will wait up to 30 seconds for the standby to reconnect before issuing a `child_node_disconnect` event.

internal/flypg/repmgr.go

@@ -388,7 +388,7 @@ func (r *RepMgr) VotingMembers(ctx context.Context, conn *pgx.Conn) ([]Member, e
 
 	var voters []Member
 	for _, member := range members {
-		if member.Role == StandbyRoleName || member.Role == WitnessRoleName {
+		if (member.Role == StandbyRoleName || member.Role == WitnessRoleName) && member.Region == r.PrimaryRegion {
 			voters = append(voters, member)
 		}
 	}

internal/flypg/zombie.go

@@ -122,7 +122,6 @@ func TakeDNASample(ctx context.Context, node *Node, standbys []Member) (*DNASamp
 			sample.totalConflicts++
 			sample.conflictMap[primary.Hostname]++
 		}
-
 	}
 
 	return sample, nil
@@ -182,7 +181,7 @@ func Quarantine(ctx context.Context, n *Node, primary string) error {
 }
 
 func DNASampleString(s *DNASample) string {
-	return fmt.Sprintf("Registered members: %d, Active member(s): %d, Inactive member(s): %d, Conflicts detected: %d",
+	return fmt.Sprintf("Voting member(s): %d, Active: %d, Inactive: %d, Conflicts: %d",
 		s.totalMembers,
 		s.totalActive,
 		s.totalInactive,