How can metrics be collected from a distributed system cluster?

To collect metrics from a distributed system cluster, specialized monitoring and data aggregation tools are usually used. Main approaches:

• Using metrics collection systems: Prometheus, Zabbix, Datadog, etc. They collect metrics from each node in the cluster via agents or exporters.

• Exporters and agents: An agent runs on each node, collecting local metrics (CPU, memory, network traffic, application metrics) and sending them to a central system.

• Centralized storage and aggregation: Collected data is aggregated and stored in a time-series database (TSDB), allowing analysis of the entire cluster's state.

• Visualization and alerts: Dashboards (Grafana) and alerting systems are used for monitoring and responding to issues.

Example: in a Kubernetes cluster, Prometheus with node_exporter is often used to collect system metrics and kube-state-metrics for cluster metrics.