The Extensions Framework in Apache CloudStack enables seamless integration of external services (XaaS) into the CloudStack ecosystem. It allows operators to register custom extensions. This mechanism supports a wide range of extension types including orchestrators, network elements, and authenticators empowering users to tailor CloudStack behaviour to suit their infrastructure needs. For example, a Proxmox extension can be registered to manage VM lifecycles through custom scripts, showcasing the power and adaptability of the framework. ---------------------- The CloudStack India User Group 2025 took place on July 11th in Greater Noida, India. The event once again brought together open-source cloud professionals, contributors, developers, and users for a day of deep technical insights, knowledge sharing, and community connection.

1. Extensions
Framework &
Orchestrate
Anything
Harikrishna Patnala, Abhishek Kumar @ CloudStack India User Group 2025

2. About us
● PMC and Committer @ Apache
CloudStack project
● Been involved with the project
for over 6 years now
● Staff Software Engineer @
ShapeBlue
Abhishek
● PMC and Committer @ Apache
CloudStack project
● Born and brought up in CloudStack
● Lead Software Engineer @
ShapeBlue
Hari

3. Why Extensions???
● Plug in External Logic Easily
○ Integrate custom scripts or tools directly into CloudStack workflows
○ Ideal for operators and developers outside the core project
● Decouples external logic from core CloudStack
● Enhances automation use-cases
● Define custom actions

4. What can be achieved ?
● Can integrate new VM provisioners or hypervisors
○ Proxmox
○ Hyper-V
○ MaaS
○ Baremetal
● Define custom actions like
○ Snapshots
○ Clone operations
○ Backups
● Can integrate new Network extensions

5. Extensions
Framework
● Integrates external
systems and workflows
● An executable binary or
script in any programming
language that acts as a
bridge between
CloudStack and the
external system
● Targeted for 4.21.0 release

6. Extensions Framework - contd.
● Extensions of different types can be defined. Current iteration
will support Orchestrator type.
● Communication using JSON structured payload
● Ability to define custom actions to provide further flexibility
● Extension binary or script file(s) will be placed at
/usr/share/cloudstack-management/extensions/<EXTENSION_NAME>
● Extension data will be stored at
/var/lib/cloudstack/management/extensions/<EXTENSION_NAME>

7. Extension - Workflow

8. Extension - Workflow Example

9. ● Operators can define
custom actions for
each extension
● Supports user-defined
input parameters,
success/error
messages, allowed
role types
● Actions can be linked
to specific resource
types
Custom
Actions

10. Custom Actions - Workflow

11. Orchestrator
Extension
● Allows instance deployment on external
systems
● Built-in extensions added for:
○ Proxmox
○ Hyper-V
● Allows deploy, start, stop, reboot,
expunge operations. More can be
added using custom actions
● (Optional) Prepare action allows
extension to update some of the fields
CloudStack instance before deployment
○ Eg. MAC address for the instance

12. Built-in Extensions

13. Adding
extension
● Basic details -
name, path, type,
type-specific
configuration
● Optional metadata
in form of key-value
pair which will be
passed to the
binary/script

14. Registering
extension
with
resource(s)
● Select resource
● Optional metadata
in form of key-value
pair which will be
passed to the
binary/script

15. Add additional resources
For orchestrator,
● Host
● Template
● Service offering (optional)

16. Use
extension
(Trigger
action)
● No specific
difference for end-
user
● For orchestrator,
end-user will select
the corresponding
template and
instance will be
deployed

17. Adding
custom
action
● Define name,
description, allowed
roles, timeout,
parameters,
success/error
messages
● Parameter can be
defined for different
types and validation
format
● Messages allow string
expansion
● Optional metadata

18. Running
custom
action
● Run action show for
the applicable
resources
● Auto generated UI
with value options,
validations

19. Demo

20. Future & What’s Next
● Will be a part of CloudStack 4.21.0 release #
● New types - network, authenticator, etc
● Usability improvements - feedback from community
● Extension marketplace???

21. Discuss
Q & A, feedback…
https://github.com/apache/cloudstack/pull/9752
https://github.com/apache/cloudstack-documentation/pull/523
https://cwiki.apache.org/confluence/display/CLOUDSTACK/CloudStack+Extensions+Fr
amework+-++Orchestartor+or+External+Deployment+Integration
https://download.cloudstack.org/testing/nightly/