Product Architecture

This topic describes the architecture of Windows Diego Cells that Pivotal Application Service for Windows deploys to run containerized .NET apps, and the stemcells that it supplies to BOSH as the operating system for the Windows Diego Cell VMs.

Overview

Operators who want to run Windows Diego Cells in Pivotal Cloud Foundry (PCF) to enable developers to push .NET apps can deploy the PASW tile.

Deploying this tile creates a separate BOSH deployment populated with the Garden Windows release, which runs on a Windows Diego Cell built from a Windows stemcell.

Once the Windows Diego Cell is running, developers can specify a Windows stack when pushing .NET apps from the command line. PCF passes the app to the Windows Diego Cell in the PASW BOSH deployment. The diagram below illustrates the process.

Windows overview

About Windows Diego Cells

App instances in PCF run inside containers. Garden is the API that creates and manages these containers. An implementation equivalent to that on Linux Diego Cells provides this infrastructure on Windows Diego Cells, utilizing native Windows Server containers.

By installing the PASW tile, operators create a Windows Diego Cell from a stemcell that contains the Windows Server operating system. Garden on Windows uses Windows containers to isolate resources on Windows Diego Cells that PCF manages alongside Linux Diego Cells.

For more information about installing the PASW tile, see Installing and Configuring PASW.

For more information about Garden, see Garden. For more information about Diego Cells, see Diego Cell in PAS Components. For more infmration about stemcells, see What is a Stemcell? in the BOSH documentation. For more information about Windows containers, see Windows and containers in the Microsoft documentation.

Components

A Windows Diego Cell includes the following components:

The following diagram illustrates the architecture of a Windows Diego Cell:

Windows cell

Container Implementation

Garden on Windows uses the following runtime plugins to create and manage Windows containers for Pivotal Application Service (PAS):

  • Container plugin winc: Creates Open Container Initiative (OCI)-compliant containers, executes processes in the containers, and sets their CPU and RAM limits. For more information about OCI compliance, see the Open Container Initiative website.

  • Network plugin winc-network: Creates a network compartment for the container, applies its DNS settings, and defines its inbound and outbound network access rules.

  • Rootfs image plugin groot: Sets up the container filesystem volume and uses the File Server Resource Manager (FSRM) API to define its disk usage quotas. For more information about the FSRM, see File Server Resource Manager (FSRM) overview in the Microsoft documentation.

About Windows Stemcells

A stemcell is a customized operating system image containing the filesystem for BOSH-managed virtual machines. When deployed, the operating system includes the BOSH Agent process, which is dedicated to communicating with the orchestrating VM, the BOSH Director. The BOSH Agent executes and monitors BOSH jobs on its VM.

Deployments of Windows Server on PCF currently use a stemcell containing Windows Server 2019.

For more information about obtaining or creating a stemcell for PASW, see Downloading or Creating Windows Stemcells.

Note: Traffic between the Gorouter and Windows stemcells is not encrypted with TLS.