Accessible application cluster topology

Abstract

Some embodiments provide a method for maintaining a cluster topology for a cluster of application instances operating across several datacenters. On a particular machine at which a particular one of the application instances operates, the method maintains a cluster topology that identifies, for each application instance of the cluster, the datacenter in which the application instance operates. From the particular application instance, the method receives a query request for at least a portion of the cluster topology through a programmatic interface. The method provides the requested portion of the cluster topology to the particular application instance. The particular application instance uses the cluster topology for processing application data based on the locations of a set of application instances within the several datacenters.

1 - 24 . (canceled) 
     
     
         25 . A method for processing data messages in a first datacenter, the method comprising:
 receiving first and second sets of data messages from a first application instance of a cluster of application instances operating on machines located across a plurality of datacenters including the first datacenter;   based on a determination that the first set of data messages are destined to an application instance in a second datacenter,
 encapsulating the data messages in the first set of data messages with an overlay network encapsulation header defined for the cluster of application instances; and 
 forwarding the encapsulated data message to the other datacenter for forwarding to destination of the first set of data messages; 
   based on a determination that the second set of data messages are destined to an application instance in the first datacenter, forwarding the data messages in the second set of data messages without encapsulating the data messages with an overlay encapsulation header.   
     
     
         26 . The method of  claim 25 , wherein a cluster manager operating on a machine along with the first application instance performs the encapsulation and forwarding operations. 
     
     
         27 . The method of  claim 26 , wherein the machine is a virtual machine. 
     
     
         28 . The method of  claim 26 , wherein the machine is a physical machine. 
     
     
         29 . The method of  claim 25 , wherein forwarding the encapsulated data message comprises forwarding the encapsulated data message to a publicly accessible machine of the second datacenter, wherein only a subset of the application instances operating in the second datacenter operate on publicly accessible machines. 
     
     
         30 . The method of  claim 25 , wherein the overlay encapsulation header allows the first set of data messages to traverse between the first and second datacenters through an overlay network defined for a cluster of application instances operating in the first and second datacenters. 
     
     
         31 . The method of  claim 25  further comprising maintaining a cluster topology of the cluster of application instances that identifies, for each application instance of the cluster, the datacenter in which the application instance operates. 
     
     
         32 . The method of  claim 25 , wherein encapsulating the first set of data messages comprises using encapsulation headers associated with a tunneling protocol. 
     
     
         33 . The method of  claim 25 , wherein the encapsulation header stores an address associated with the second application instance that is an overlay address assigned to the second application instance in the overlay network. 
     
     
         34 . The method of  claim 25 , wherein the application instances of the cluster form a complete graph in an overlay network, wherein each application instance is connected to every other application instance in the cluster. 
     
     
         35 . A non-transitory machine readable medium storing a program for processing data messages in a first datacenter, the program for execution by at least one processing unit, the program comprising sets of instructions for:
 receiving first and second sets of data messages from a first application instance of a cluster of application instances operating on machines located across a plurality of datacenters including the first datacenter;   based on a determination that the first set of data messages are destined to an application instance in a second datacenter,
 encapsulating the data messages in the first set of data messages with an overlay network encapsulation header defined for the cluster of application instances; and 
 forwarding the encapsulated data message to the other datacenter for forwarding to destination of the first set of data messages; 
   based on a determination that the second set of data messages are destined to an application instance in the first datacenter, forwarding the data messages in the second set of data messages without encapsulating the data messages with an overlay encapsulation header.   
     
     
         36 . The non-transitory machine readable medium of  claim 35 , wherein a cluster manager operating on a machine along with the first application instance performs the encapsulation and forwarding operations. 
     
     
         37 . The non-transitory machine readable medium of  claim 36 , wherein the machine is a virtual machine. 
     
     
         38 . The non-transitory machine readable medium of  claim 36 , wherein the machine is a physical machine. 
     
     
         39 . The non-transitory machine readable medium of  claim 35 , wherein the set of instructions for forwarding the encapsulated data message comprises a set of instructions for forwarding the encapsulated data message to a publicly accessible machine of the second datacenter, wherein only a subset of the application instances operating in the second datacenter operate on publicly accessible machines. 
     
     
         40 . The non-transitory machine readable medium of  claim 35 , wherein the overlay encapsulation header allows the first set of data messages to traverse between the first and second datacenters through an overlay network defined for a cluster of application instances operating in the first and second datacenters. 
     
     
         41 . The non-transitory machine readable medium of  claim 35 , the program further comprising a set of instructions for maintaining a cluster topology of the cluster of application instances that identifies, for each application instance of the cluster, the datacenter in which the application instance operates. 
     
     
         42 . The non-transitory machine readable medium of  claim 35 , wherein the set of instructions for encapsulating the first set of data messages comprises a set of instructions for using encapsulation headers associated with a tunneling protocol. 
     
     
         43 . The non-transitory machine readable medium of  claim 35 , wherein the encapsulation header stores an address associated with the second application instance that is an overlay address assigned to the second application instance in the overlay network. 
     
     
         44 . The non-transitory machine readable medium of  claim 35 , wherein the application instances of the cluster form a complete graph in an overlay network, wherein each application instance is connected to every other application instance in the cluster.