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:

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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)

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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.

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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

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Installation

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

2. SCP the tarball to your XOA:

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

3. Create the plugin folder:

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

4. 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
   

5. Restart xo-server:

   sudo systemctl restart xo-server
   

6. 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

7. Enable and configure the plugin in XO:
   Settings -> Plugins -> affinity-manager -> Enable

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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)

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LINKS

GitHub: https://github.com/johnezero/xo-tag-automation_plugin

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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...