[SOLR-15694] Concept of node roles and non-data nodes

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 9.0
• Component/s: AutoScaling
• Assignee: Unassigned
• Reporter: Ishan Chattopadhyaya
• Created: 13/Oct/21 12:14
• Updated: 06/Jul/24 20:19
• Resolved: 21/Sep/22 02:04

Description

I think we should have first class support for starting a Solr node in a mode whereby no cores will be placed on them. These nodes are useful for certain scenarios:

1. Dedicated overseer nodes
2. Nodes where only plugins are installed and used (e.g. cluster/node level plugins)
3. Dedicated nodes for querying (more on this to come later).

Today, to achieve this effect, one can:
1. start a node (which will make it join live_nodes and be immediately available for replica placement).
2. Put replica placement rules or autoscaling policies to prevent replicas from being placed there. This is not standardized, 8x has two ways to achieve this (replica placement rules and autoscaling framework), 9x has a new autoscaling framework.

Proposing a start parameter for starting a node that starts the node in this configuration, and then internally this is handled appropriately (across 8x and 9x). This should be Kubernetes/Docker friendly as well, since it is easy to add an additional parameter for a startup (instead of putting things into autoscaling.json in ZK via init scripts).

Issue Links

• is related to: SOLR-15715 Dedicated query coordinator nodes in the solr cluster
• links to: GitHub Pull Request #403