[jira] [Created] (AMBARI-26661) Telemetry scrape targets never appear on a freshly installed cluster

["Jefferson Almeida (Jira)" <ji...@apache.org>]

Jefferson Almeida created AMBARI-26661:
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             Summary: Telemetry scrape targets never appear on a freshly installed cluster
                 Key: AMBARI-26661
                 URL: https://issues.apache.org/jira/browse/AMBARI-26661
             Project: Ambari
          Issue Type: Bug
          Components: ambari-server, metrics
    Affects Versions: 3.1.0
         Environment: Rocky Linux 9
            Reporter: Jefferson Almeida
             Fix For: 3.1.0


On a freshly installed cluster, VMAGENT never receives component scrape targets for
HDFS/YARN/HBase. The per-host telemetry assignment stays empty until something
unrelated forces a recompile — a cluster config change, or an ambari-server restart.

Root cause: TelemetryHolder's only per-component subscription is
ServiceComponentInstalledEvent. ServiceComponentHostImpl publishes that event from
the code path that first persists the host component row, while its desired state is
still INIT. TelemetryAssignmentCompiler.compileCluster() skips any component whose
state is not installed, and isInstalled() accepts only INSTALLED, STARTING, STARTED,
STOPPING, UPGRADING, DISABLED and UNKNOWN — INIT is not among them. So the first
assignment compiled for a host contains no component targets, and nothing revisits it
on the normal install/start path: handleEvent(), which processes the real state
transitions, refreshes HostLevelParamsHolder but never TelemetryHolder.

Steps to reproduce:
1. Install a new cluster with VICTORIAMETRICS plus HDFS/YARN/HBase.
2. Once all components are STARTED, inspect the VMAGENT scrape targets (or the
   telemetry assignment sent to the agent) — no component targets are present.
3. Change any cluster config, or restart ambari-server, and the targets appear.

Expected: component scrape targets are present once the components reach an installed
state, without any unrelated action.



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