Separating the Worker and Manager Nodes

WSO2 Carbon version 4.0.0 onwards supports deployment models that consist of 'worker' nodes and 'manager' nodes. A worker node serves requests received by clients, whereas a manager node deploys and configures artifacts (web applications, services, proxy services, etc.). 

The worker/manager setup separates a WSO2 product's UI components, management console, and related functionality with its internal framework. Typically, the manager nodes are in read-write mode and authorized to make configuration changes. The worker nodes are in read-only mode and authorized only to deploy artifacts and read configurations.

Why separate the worker and manager nodes

1. Improved security: Manager nodes are typically behind a firewall that only allows admin access. They are exposed to clients running within the organization only, while worker nodes can be exposed to external clients.
2. Proper separation of concerns: Management nodes specialize in the management of the setup while worker nodes specialize in serving requests to deployment artifacts. Only management nodes are authorized to add new artifacts into the system or make configuration changes.
3. Specific worker-node tasks: Worker nodes can only deploy artifacts and read configuration. Worker nodes are limited only for specific tasks.
4. Lower memory requirements: There is a lower memory footprint in the worker nodes because the OSGi bundles related to the management console and UI are not loaded to them. This is also good for memory utilization.

Worker/Manager separated clustering patterns

Since all WSO2 products are built on the cluster-enabled Carbon platform, you can cluster them in the same way depending on which deployment pattern you use. The clustering pattern determines the process of separating the worker and manager nodes. You can select one of the following patterns based on your load and the target expenditure. 

Worker/Manager clustering deployment pattern 1

This pattern involves two worker nodes in a cluster. The worker is in high-availability mode while the manager is not. This pattern is suitable in situations where it is rare to deploy applications or modify a running application and therefore, can run with only a single manager node. However, you need multiple worker nodes to ensure that the application runs continuously.

This mode is rarely used. The preferred mode is having two management nodes in Active/Passive mode as in deployment pattern 2.

Worker/Manager clustering deployment pattern 2

This pattern has two manager nodes in one cluster and two worker nodes in a separate cluster. The management node is in Active/Passive mode for high availability. It is generally not recommended to put a manager node in the Active/Active mode, but if you want high availability for your data center and location-based services, it is useful. 

This pattern is useful in scenarios where the application deployment/modification might be frequent and therefore, need a cluster of manager nodes. However, if the load is less, you can share a single load balancer with the worker cluster.

Worker/Manager clustering deployment pattern 3

This pattern has two manager nodes in one sub-domain and two worker nodes in a separate sub-domain. The manager and worker subdomains are parts of a single WSO2 product cluster domain. Both subdomains use their own load balancer while existing within the same cluster. Note that multiple load balancers require you to follow several unique configurations. 

This pattern is similar to deployment pattern 2. However, the application/modification load (or any other administrative load) might be high, so there is a dedicated load balancer for the manager cluster to prevent this load from affecting the load of the worker cluster.