Setup info

Firewall

The only ports allowed are 80,443 and 22

Services

All services are controlled via systemd (/etc/systemd/system) prometheus.service alertmanager.service node_exporter.service

Grafana

The service its installed from repository, so it can be upgraded via yum update command The dashboards have a regex filter /pfm./ and /std./

Prometheus

Data retention is 60 days, in can be changed in the systemd unit file To undapte prometheus binary, you can download the latest from https://prometheus.io/download/

Add prometheus clients

1. Downloaded node_exporter binary from Prometheus download page directly https://prometheus.io/download/
2. Create and enable the systemd unit file

$ cat < /etc/systemd/system/node_exporter

Paste the text below and press CTRL+C

[Unit]

Description=Prometheus exporter for machine metrics Documentation=https://github.com/prometheus/node_exporter

[Service]

Restart=always ExecStart=/opt/monitoring/prometheus/node_exporter/node_exporter --collector.systemd

ExecReload=/bin/kill -HUP $MAINPID TimeoutStopSec=20s SendSIGKILL=no

[Install]

WantedBy=multi-user.target

3. Run the commands to enable the unit file on boot and start the service

$ systemctl enable node_exporter $ systemctl start node_exporter

4. On the client allow port 9100 incoming traffic on the firewall
5. Add client hostname in prometheus.yml config file $ vim /opt/monitoring/prometheus/prometheus.yml

Add the hostname with a comma separated on the following block and save the file

• job_name: 'node_exporter'

  static_configs:

  • targets: ['localhost:9100', '']

Postfix server - to send the email alerts

Postfix server has the default settings and can only send emails, port 25 its not allowed inbound

ALERTS

Check alerts from command line

$ cd /opt/monitor/alertmanager $./amtool alert --alertmanager.url=http://127.0.0.1:9093

Check alerts in Prometheus web gui

http://127.0.0.1:9090/alerts

Check alerts in AlertManager web gui

http://127.0.0.1:9093/#/alerts

A handy alerts list

https://awesome-prometheus-alerts.grep.to/rules.html

To setup additional alert rules edit the following config file

$vim /opt/monitoring/prometheus/alert_rules.yml

Example additional rule declaration

Alert when a systemd unit is in failed state, it can be for a specific service

• alert: SystemdServiceFailed expr: node_systemd_unit_state{state="failed", name="alertmanager.service"} == 1 for: 5m labels: severity: critical annotations: summary: Host SystemD service crashed (instance {{ $labels.instance }}) description: SystemD service crashed\n VALUE = {{ $value }}\n LABELS: {{ $labels }}