Fixes to make these changes upgrade compatible

Author: davissp14

cmd/pg_unregister/main.go

@@ -45,7 +45,7 @@ func processUnregistration(ctx context.Context) error {
 
 	machineID := string(machineBytes)
 
-	if len(machineID) != 16 {
+	if len(machineID) != 14 {
 		return fmt.Errorf("invalid machine id: %s. (expected length 16, got %d)", machineID, len(machineBytes))
 	}
 

internal/flypg/repmgr.go

@@ -363,7 +363,14 @@ func (r *RepMgr) Members(ctx context.Context, pg *pgx.Conn) ([]Member, error) {
 			return nil, err
 		}
 
-		member.Hostname = r.machineIDToDNS(member.Name)
+		// Assume we are working with a machineID if the name is 14 characters long.
+		if len(member.Name) == 14 {
+			member.Hostname = r.machineIDToDNS(member.Name)
+		} else {
+			// Member name is the private IP.
+			member.Hostname = member.Name
+			member.Name = ""
+		}
 
 		members = append(members, member)
 	}
@@ -399,7 +406,14 @@ func (r *RepMgr) PrimaryMember(ctx context.Context, pg *pgx.Conn) (*Member, erro
 		return nil, err
 	}
 
-	member.Hostname = r.machineIDToDNS(member.Name)
+	// Assume we are working with a machineID if the name is 14 characters long.
+	if len(member.Name) == 14 {
+		member.Hostname = r.machineIDToDNS(member.Name)
+	} else {
+		// Member name is the private IP.
+		member.Hostname = member.Name
+		member.Name = ""
+	}
 
 	return &member, nil
 }
@@ -455,6 +469,7 @@ func (r *RepMgr) MemberByNodeName(ctx context.Context, pg *pgx.Conn, name string
 	return &member, nil
 }
 
+// Deprecated: Use MemberByNodeName instead.
 func (*RepMgr) MemberByHostname(ctx context.Context, pg *pgx.Conn, hostname string) (*Member, error) {
 	var member Member
 	sql := fmt.Sprintf("select node_id, node_name, location, active, type from repmgr.nodes where node_name = '%s';", hostname)