PaaS Cluster Overview

PaaS Cluster Overview

A Platform as a Service cluster is an isolated group of servers and supporting resources that operate together as one system. It provides the infrastructure required to develop, test, deploy, run, monitor, and maintain hosted applications.

A typical PaaS cluster contains user hosts for customer containers and dedicated infrastructure hosts that coordinate internal platform operations. Container lifecycle automation is handled through the Jelastic Environment Manager, while platform updates and fixes are distributed through the Patcher component.

The Jelastic License Server is a centralized service responsible for licensing, activation of new installations and hosts, error collection, patching coordination, template management, and other shared platform functions.

On this page
ClusterA unified group of interconnected physical or virtual servers.
HostA server that runs infrastructure services or isolated user containers.
JEMThe environment-management component that automates container lifecycle operations.
PatcherThe subsystem used to deliver platform updates and fixes.
JLSThe centralized licensing and platform coordination service.
Tip: Refer to your platform’s Basics & Terminology documentation for definitions of environments, containers, nodes, and other lower-level components. Hardware requirements for infrastructure and user hosts should also be reviewed before planning a deployment.

Cluster

A cluster is a set of interconnected servers combined into one PaaS platform. It exposes administration and user interfaces together with APIs for provisioning resources, managing applications, and controlling the complete application lifecycle.

PaaS cluster infrastructure scheme
PaaS cluster infrastructure scheme

Host

A host, also called a hardware host, is a physical bare-metal server or virtual machine that runs isolated containers. The platform separates internal infrastructure services from customer workloads by using dedicated infrastructure hosts and user hosts.

PaaS infrastructure and user hosts
Infrastructure hosts and user hosts within a PaaS cluster

Infrastructure hosts run internal services that allocate resources, process platform requests, analyze activity, and support maintenance operations. User hosts are divided into smaller isolated containers that form the runtime foundation for customer environments.

This separation and container-based allocation model improves workload density and makes efficient use of available compute resources. Administrators can view and manage the host inventory through the cluster administration panel.

Cluster administration panel
Host management in the cluster administration panel

JEM

JEM, or Jelastic Environment Manager, is the platform component that adds automation and management logic to containers. It controls lifecycle operations and provides additional platform capabilities for hosted applications.

JEM is available as open-source software through its public GitHub repository.

Patcher

The Patcher is a dedicated subsystem used to deliver platform updates and corrective fixes. It operates with a limited-purpose environment in which each container represents a corresponding infrastructure component, together with identifiers and network information required for the patching process.

PaaS patching process
Platform patching workflow

JLS

JLS, or Jelastic License Server, is an internal centralized service connected to PaaS installations. It manages licensing and activation, collects platform errors, maintains default template information, and coordinates patching across multiple platform installations.

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