Apache CloudStack 4.21 will introduce a category‑driven Template and ISO image‑selection UI, fully programmable OS‑category APIs, and an updated default list that mirrors today’s most‑used operating systems. Users will find Templates and ISOs faster, while operators gain fine‑grained control over how operating systems are organised and surfaced.

Feature Overview

Before CloudStack 4.21, the image picker was a flat A–Z list with only text search. Templates for different operating systems—or specialised builds like GPU‑enabled kernels—looked identical unless admins embedded hints in the name. The backend categories were hard‑coded, so any taxonomy changes meant tedious work‑arounds.

This new feature solves this in two steps:

1. Modern image picker – groups images by OS category, highlights featured builds and supports deep links for one‑click launches.
2. Dynamic category management – new endpoints addOsCategory, updateOsCategory, deleteOsCategory, and an extended updateOsType allow operators to create, rename or retire categories without downtime. listTemplates and listIsos now accept category filters, keeping GUIs and automation aligned.

Together, these changes let users locate images faster while giving operators granular, programmatic control over how operating‑system options are presented.

Image Picker in Creation & Reinstall Flows

CloudStack 4.21 and later surfaces the modern, category‑driven picker in every workflow that touches an Image, providing a consistent experience across the platform.

Deploy Instance / Appliance

When the wizard reaches Select Image, Templates and ISOs appear under their OS category, with any featured category pinned to the top. A deep link such as /template/<id>?deploy=true or /iso/<id>?deploy=true opens the wizard pre‑loaded with that image.

Reinstall Instance

Selecting Reinstall on an Instance opens the same picker, allowing users to move to a newer or security‑hardened build without scrolling a long list.

Create Auto-Scale Group

During Launch Configuration, the category view ensures operators pick the correct base image for every scale-out node.

Tip: Keep imageSelectionInterface: legacy in config.json  for a particular UI installation until you’re ready to switch—then flip to modern for a seamless rollout.

Default OS Categories

Debian-based

• Ubuntu
• Debian

RHEL-compatible

• Fedora
• CentOS
• Rocky Linux
• Alma Linux
• Oracle
• RedHat

SUSE Family

• SUSE

Non-Linux / Misc

• Windows
• Other

API Examples

# Add a new category
cloudmonkey add oscategory name="Hardened Linux" featured=true

# Move an existing OS type to the new category
cloudmonkey update ostype id=<OSTYPE_UUID> oscategoryid=<HARDENED_UUID>

# List only featured categories
cloudmonkey list oscategories featured=true

# List templates belonging to the Ubuntu category
cloudmonkey list templates ostypecategory="Ubuntu"

Backward Compatibility

Templates and ISOs that lack an explicit category automatically appear in Other, ensuring they remain selectable until re‑classified. Existing deployments can keep the legacy picker per Zone or Account until migration is complete.

This feature is available from Apache CloudStack 4.21!

Abhishek Kumar

Abhishek Kumar is a software engineer by profession. His personal interests and hobbies are technology, politics and sports. Abhishek is experienced in development and management of a variety of desktop and mobile applications. He has a particular interest in mobile application development, designing and developing highly interactive and intuitive mobile, desktop applications GUI.
Abhishek became part of ShapeBlue in 2019 and is currently an active Apache CloudStack Committer.

You can learn more about Abhishek and his background by reading his Meet The Team blog.