[SOLR-14915] Prometheus-exporter should not depend on Solr-core

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 9.0
• Component/s: contrib - prometheus-exporter
• Assignee: David Smiley
• Reporter: David Smiley
• Created: 06/Oct/20 18:35
• Updated: 12/May/22 00:26
• Resolved: 27/Nov/20 20:10

Description

I think it's crazy that our Prometheus exporter depends on Solr-core – this thing is a client of Solr; it does not live within Solr. The exporter ought to be fairly lean. One consequence of this dependency is that, for example, security vulnerabilities reported against Solr (e.g. Jetty) can (and do, where I work) wind up being reported against this module even though Prometheus isn't using Jetty.

From my evaluation today of what's going on, it appears the crux of the problem is that the prometheus exporter uses some utility mechanisms in Solr-core like XmlConfig (which depends on SolrResourceLoader and the rabbit hole goes deeper...) and DOMUtils (further depends on PropertiesUtil). It can easy be made to not use XmlConfig. DOMUtils & PropertiesUtil could move to SolrJ which already has lots of little dependency-free utilities needed by SolrJ and Solr-core alike.

Issue Links

• relates to: SOLR-14953 Create an individual Docker image for the Prometheus Exporter
• links to: GitHub Pull Request #1972

Sub-Tasks

• Move DOMUtil and PropertiesUtil to SolrJ, o.a.s.common/util: Closed