aggregation alerting rules Alertmanager application batch job Blackbox exporter bytes cardinality Chapter client library config Consul counter dashboard datacenter debugging default endpoint evaluation expose expr expression browser external labels Figure file descriptors filesystem function gauge global Prometheus going Grafana graph group_left HAProxy Hello World histogram hostname icmp instance label instant vector job label job_name JSON Kubernetes label names label values latency level=info logs look machine match metadata metric name metric_relabel_configs monitoring systems Node exporter notification operator output probe probe_success Prome Prometheus servers prometheus_client import prometheus.yml PromQL Pushgateway Python quantile query range vector recording rules regex regular expression relabel_configs requests result route samples scalar scrape interval scrape_configs selector service discovery setup shown in Example SNMP source_labels static_configs StatsD target labels templating textfile collector theus timestamp TYPE URL parameter users wget WSGI YAML