Monitoring

RaftNodeReport contains detailed information about internal state of a RaftNode, such as its Raft role, term, leader, last log index, and commit index. We can feed our external monitoring systems with these information pieces as follows:

1. We can build a simple pull-based system to query RaftNodeReport objects via RaftNode.getReport() and publish those objects to any external monitoring system.

2. MicroRaft contains another abstraction, RaftNodeReportListener which is called by Raft nodes anytime there is an important change in the internal Raft state, such as leader change, term change, or snapshot installation. We can also use this abstraction to capture RaftNodeReport objects and notify external monitoring systems promptly with a push-based approach.

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Micrometer integration

MicroRaft offers a module to publish Raft node metrics to external systems easily via the Micrometer project. Just add the following dependency to the classpath for using the Micrometer integration.

<dependency>
    <groupId>io.microraft</groupId>
    <artifactId>microraft-metrics</artifactId>
    <version>0.1</version>
</dependency>

RaftNodeMetrics implements the RaftNodeReportListener interface and can be injected into created RaftNode instances via RaftNodeBuilder.setRaftNodeReportListener(). Then, several metrics extracted from published RaftNodeReport objects are passed to meter registries.