Clopla is a Java library that, given a set of virtual machines and a set of hosts, computes an optimized placement for the VMs.

Clopla supports:

• Several construction heuristics: first fit, first fit decreasing...
• Several local search heuristics: simulated annealing, tabu search, hill climbing...
• Several placement policies: consolidate the VMs, distribute the VMs, place the VMs randomly, and group the VMs by service or application.

Clopla uses OptaPlanner.

Add this dependency to your pom.xml:

<dependency>
   <groupId>es.bsc</groupId>
   <artifactId>clopla</artifactId>
   <version>1.0.0</version>
</dependency>

Clopla is very easy to use. You just need to define a set of VMs, a set of hosts, and some options for the placement engine: the scheduling policy, the maximum running time, a construction heuristic, a local search heuristic, and whether some VMs are required to be deployed in specific hosts.

For example, suppose that we want to find an optimized placement using the following options:

• Scheduling policy: consolidation.
• Timeout: 30 seconds.
• Construction heuristic: first fit decreasing.
• Local Search heuristic: hill climbing.
• We are not interested in pinning some VMs to specific hosts.

The java code for finding a placement using those options is:

IClopla clopla = new Clopla();
VmPlacementConfig vmPlacementConfig = new VmPlacementConfig.Builder(
    Policy.CONSOLIDATION, // Scheduling policy
    30, // Timeout
    ConstructionHeuristic.FIRST_FIT_DECREASING, // Construction heuristic
    new HillClimbing(), // Local Search heuristic
    false) // Deploy VMs in specific hosts?
    .build();
System.out.println(clopla.getBestSolution(hosts, vms, vmPlacementConfig)); // get placement and print it

The only thing missing from the example is knowing how to instantiate a list of VMs and a list of hosts:

// Create a list of VMs that contains a VM with id = 1, cpus = 2, ramMb = 1024, and diskGb = 4
List<Vm> vms = new ArrayList<>();
Vm vm = new Vm.Builder((long) 1, 2, 1024, 4).build();
vms.add(vm);
// Instantiate a lists of hosts that contains a host with id = 1, hostname = myHost, cpus = 4, ramMb = 8192,
// diskGb=100, and that is on
List<Host> hosts = new ArrayList<>();
Host host = new Host((long) 1, "myHost", 4, 8192, 100, false);
hosts.add(host);

Every local search heuristic can be configured with different options. You need to specify those options when instantiating the local search heuristic. For example, the tabu search heuristic accepts an entity tabu size and an accepted count limit. All these configuration options are very well explained in the [Optaplanner documentation] (http://docs.jboss.org/optaplanner/release/6.0.1.Final/optaplanner-docs/html/localSearch.html).

You can find a complete usage example in the examples/ExampleClient.java class.

Code released under the Apache 2.0 license

This work is supported by the European Union under FP7-SMARTCITIES-2013 contract 608679 and FP7-ICT-2013-10 contract 610874.