Cluster Management

• Accessing the cluster from within a component
• Deploying modules and verticles to the cluster
• Undeploying modules and verticles from the cluster
• Checking if a module or verticle is deployed
• Deploying modules and verticles with HA
• Working with HA groups

• Java
• Java 8
• Python
• Javascript

Vertigo clusters support remote deployments over the event bus through Xync. Users can use the Vertigo cluster API to remotely deploy Vert.x modules and verticles from Vertigo components.

Accessing the cluster from within a component

The Xync cluster is made available to users through the cluster field within the ComponentVerticle class. The cluster within any given component will always reference the Vertigo cluster to which the component’s parent network belongs. This means that deployments made through the cluster will be separated in the same way that networks are separated from each other across clusters.

Deploying modules and verticles to the cluster

The Vertigo cluster supports remote deployment of modules and verticles over the event bus. The Cluster API wraps the event bus API and mimics the core Vert.x Container interface. To deploy a module or verticle simply call the appropriate method on the component Cluster instance:

public class MyComponent extends ComponentVerticle {
  @Override
  public void start() {
    cluster.deployVerticle("foo", "foo.js", new Handler<AsyncResult<String>>() {
      public void handle(AsyncResult<String> result) {
        if (result.succeeded()) {
          // Successfully deployed the verticle!
        }
      }
    });
  }
}

public class MyComponent extends ComponentVerticle {
  @Override
  public void start() {
    cluster.deployVerticle("foo", "foo.js", (r) -> {
      if (result.succeeded()) {
        // Successfully deployed the verticle!
      }
    });
  }
}

The Cluster API differs in one important aspect from the Container API. Because cluster deployments are remote, users must provide an explicit deployment ID for each deployment. This ensures that even if the instance from which the module/verticle was deployed fails, the deployment can still be referenced from different Vert.x instances. If the deployment ID of a deployment already exists then the deployment will fail.

The internal component cluster is the same cluster to which the component’s parent network belongs. That means that deployment IDs are unique to each cluster. You can deploy a module with the deployment ID foo in two separate clusters at the same time.

Undeploying modules and verticles from the cluster

To undeploy a module or verticle from the cluster call the undeployModule or undeployVerticle method, using the user-defined deployment ID.

cluster.undeployVerticle("foo");

Deploying modules and verticles with HA

Like Vert.x clusters, the Vertigo clusters supports HA deployments. By default, modules and verticles are not deployed with HA enabled.

cluster.deployVerticle("foo", "foo.js", null, 1, true);

The last argument in the arguments list indicates whether to deploy the deployment with HA. When a Vertigo cluster node fails, any deployments deployed with HA enabled on that node will be taken over by another node within the same group within the cluster.

Checking if a module or verticle is deployed

Since deployment IDs in Vertigo clusters are user-defined, users can determine whether a module or verticle is already deployed with a specific deployment ID. To check if a deployment is already deployed in the cluster use the isDeployed method.

cluster.isDeployed("foo", new Handler<AsyncResult<Boolean>>() {
  public void handle(AsyncResult<Boolean> result) {
    boolean deployed = result.result(); // Whether the module or verticle is deployed
  }
});

cluster.isDeployed("foo", (r) -> {
  boolean deployed = result.result(); // Whether the module or verticle is deployed
});

To check if a module or verticle is deployed over the event bus send a check message to the cluster, specifying the module or verticle as the check type.

{
  "action": "check",
  "type": "verticle",
  "id": "foo"
}

If the request is successful, the cluster will reply with a result containing a boolean indicating whether the deployment ID exists in the cluster.

Working with HA groups

Vertigo’s HA grouping mechanism is intentionally designed to mimic the core HA behavior. Each Vertigo node can be assigned to a specific HA group, and when a node fails its HA deployments will be taken over by another node in the same group.

Modules or verticles can also be deployed directly to a specific HA group. To deploy a module or verticle to an HA group call the deployModuleTo or deployVerticleTo methods respectively, passing the target HA group as the second argument (after the deployment ID).

cluster.deployVerticleTo("foo", "my-group", "foo.js");

By default, all deployments are deployed to the __DEFAULT__ HA group.