PaaS Cluster Overview

PaaS is an isolated cluster with a group of servers and other resources that act like a single system for providing the ability to develop, debug, deploy, test, run, and maintain hosted applications.

PaaS Cluster consists of user hosts, where the end-user containers are stored, and a cluster orchestrator - infrastructure hosts that control all the internal processes. Additionally, clusters utilize the JEM (Jelastic Environment Manager) module to control the containers' lifecycle processes. The Patcher component is responsible for delivering updates and fixes to the platform. Lastly, JLS (Jelastic License Server) is a global, centralized component that manages licensing (activation of the new installations and hosts), errors analysis, patching initiation, and more.

Follow the links to the sections below to get detailed information on these components:

Tip: The description and terminology for the smaller components (environments, containers, etc.) can be checked in the dedicated Basics & Terminology document.

The requirements for infra and user hosts are stated in the Hardware Requirements document.

Also, read the Operations Guide instructions to learn which actions (and how) can be performed with the PaaS Cluster components.


Cluster is a group of physical servers (hosts) interconnected into a single entity - PaaS. The platform provides intuitive UI for both admins and users and robust API to develop, debug, deploy, test, run, and maintain hosted applications.

PaaS cluster scheme


Host or Hardware Host (previously known as “hardware node” or “hardnode") is a physical bare-metal server (or VM), which stores isolated virtual containers. The platform separates infrastructure components from the end-users containers by utilizing dedicated infra hosts and user hosts.

PaaS infra and user hosts

Infrastructure hosts (Cluster Orchestrator) run a set of internal components for managing resources, processing requests, analyzing users' behaviors, and supporting PaaS system maintenance.

The platform slices User Hosts into small isolated virtual containers, which will be used for the end-user environments. Such division is the core for the industry-leading density and system resource utilization efficiency.

You can manage the host’s list via the Cluster Admin (JCA) panel:

JCA - cluster admin panel


JEM or Jelastic Environment Manager is an open-source platform component that injects smart logic into containers to automate all the lifecycle processes. It gives extra features and automation for the hosted applications.

As open-source software, JEM is available at the jelastic/jem GitHub repository.


Patcher is a sub-platform for delivering updates and fixes to the main platform. It has limited functionality and only one environment, which is named “jelastic” and corresponds to the main platform. Each container of this environment represents the appropriate infrastructure component, including its CTID, external/internal IPs, etc.

platform patching process


JLS or Jelastic License Server is an internal server that is responsible for centralized licensing (activation of the new installations and hosts), JErrors collection, default templates list management, multiple platforms patching, etc. The server is connected to all PaaS installations.

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