Affinity Manager Plugin: Tag-Based VM placement and grouping control

johnnezero

Affinity Manager Plugin

WHAT: In keeping with my previous project (Tag-Automation Plugin, found here), I am releasing the Affinity Manager Plugin, which is a fully tag-driven plugin for Xen Orchestra. It is designed to provide VM placement and grouping controls based on assigned tags, which are managed by predefined tag rules.

PROGRAM FEATURES

Host Affinity (RunOn) Run VMs on specific host group (e.g. a particular data center or set of hosts)
Host Anti-Affinity (NotOn) Keep VMs off of specific host group
VM Keep-Together (KeepTogether) Keep named group of VMs on the same host (follows Leader VM)
VM Separation (KeepApart) Spread named group of VMs across unique hosts (best-effort)

VM TAG SYNTAX

Apply tags to VMs in the XO UI:

VM TAG / RULE	EXAMPLE	MEANING
`AM-RunOn_{HostGrpName}`	`AM-RunOn_P1-DC2-HOST`	VM should run on hosts tagged `P1-DC2-HOST`
`AM-NotOn_{HostGrpName}`	`AM-NotOn_P2-DC1-HOST`	VM should NOT run on hosts tagged `P2-DC1-HOST`
`AM-KeepTogether_{GrpName}`	`AM-KeepTogether_AppStack1`	Keep all group VMs on same host (follows Leader VM)
`AM-KeepApart_{GrpName}`	`AM-KeepApart_DBCluster1`	Spread group VMs across unique hosts (best effort)

Note: Multiple rules can be combined on a single VM. For example, a VM can have both
AM-RunOn_P1-DC1-HOST and AM-KeepTogether_WebCluster simultaneously.

HOST TAG SYNTAX

Apply tags to hosts in the XO UI (i.e. to define host groups):

EXAMPLE HOST TAG	POOL	LOCATION
`P1-DC2-HOST`	POOL-1	Data Center 2
`P2-DC1-HOST`	POOL-2	Data Center 1

INSTALLATION

Download the latest airgap release tarball from GitHub:
https://github.com/johnezero/xo-affinity-manager/releases

SCP the tarball to your XOA:

scp xo-affinity-manager-airgap-vX.X.X.tar.gz <xoa-user>@<xoa-ip>:/tmp/

Create the plugin folder:

sudo mkdir -p /usr/local/lib/node_modules/xo-server-affinity-manager

Extract directly into the plugin directory:

sudo tar -xzvf /tmp/xo-affinity-manager-airgap-vX.X.X.tar.gz -C /usr/local/lib/node_modules/xo-server-affinity-manager/ --strip-components=1

Restart xo-server:
```
sudo systemctl restart xo-server
```
Verify registration:
```
sudo journalctl -u xo-server -n 100 --no-pager | grep -A3 "affinity-manager"
```
You should see:
[INFO] xo-affinity-manager: Plugin factory called -- xo context: YES
[INFO] xo-affinity-manager: Plugin loaded -- waiting for core started.
xo:plugin INFO successfully register affinity-manager
Enable and configure the plugin in XO:
Settings -> Plugins -> affinity-manager -> Enable

CONFIGURATION

(XO > Settings > Plugins)

Enforcement Schedule — Run every 15 minutes, hourly, or daily (configurable)
Dry Run Mode — Logs all intended actions without migrating anything (default: ON)
Log Path — Configurable path to the log (Created automatically if it does not exist).
Pool Safety — Cross-pool migration is always blocked (i.e. Plugin only migrates VMs within the same pool)
Log Rotatate — Rotate/compress log files at 10 MB (keeping 3 archives)

LINKS

GitHub: https://github.com/johnezero/xo-affinity-manager

STANDARD DISCLAIMER HERE

This software is provided AS-IS without any express or implied warranty.
While this plugin is being used in a production environment managing live VMs,
you should always review the code and test it in a non-production environment
before full deployment.
Note: The plugin is designed to ONLY take action on VMs with specific predefined tags assigned -- all other VMs are never touched.
Use Dry-Run mode to preview all changes before applying them.
That said, as always - your mileage may vary...