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Cloud Native Infrastructure: Part 2 Monitoring

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Introduction

Prometheus

Prometheus is an open-source systems monitoring and alerting toolkit.

Installation

In docker-compose.yml:

services:
  prometheus:
    image: prom/prometheus
    restart: always
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
      - ./prometheus:/prometheus
    ports:
      - 9090:9090
    user: root

Prometheus provides a UI at :9090 by default.

Node Exporter

Node Exporter is designed ad a Prometheus exporter for hardware and OS metrics exposed by *NIX kernels.

According to the documentation, it’s not recommended to deploy it as a Docker container because it requires access to the host system, so you could just download the binary release version.

$ wget https://github.com/prometheus/node_exporter/releases/download/v0.18.0/node_exporter-0.18.0.linux-amd64.tar.gz
$ tar -xvf node_exporter-0.18.0.linux-amd64.tar.gz
$ cd node_exporter-0.18.0.linux-amd64
# It's recommended to run the following instruction in tmux in order to keep it running after exit.
$ ./node_exporter &

After started, node_exporter will be listening at :9100.

Service Registry

In order to combine service node-exporter with Consul, a config directory should be configured.

In consul.d/node_exporter.json:

{
  "service": {
    "name": "node_exporter",
    "tags": ["exporter"],
    "address": "$PRIVATE_IP_ADDRESS",
    "port": 9100
  }
}

In docker-compose.yml of Consul:

version: "3"
services:
  consul:
    image: consul
    container_name: consul
    ports:
      - "8300:8300"
      - "8400:8400"
      - "8500:8500"
      - "8600:53/udp"
    volumes:
      - ./consul.d:/etc/consul.d
    command: agent -dev -client 0.0.0.0 -config-dir=/etc/consul.d

Configuration

In prometheus.yml:

global:
  scrape_interval: 15s

scrape_configs:
  # Self-monitoring
  - job_name: "prometheus"
    static_configs:
      - targets: ["localhost:9090"]
      - labels:
          instance: prometheus
  # Without service discovery
  - job_name: "node_exporter"
    static_configs:
      - targets: ["$PRIVATE_IP_ADDRESS:9100"]
      - labels:
          instance: node_exporter
  # With service discovery, discard the job above
  - job_name: "node_exporter"
    consul_sd_configs:
      - server: $PRIVATE_IP_ADDRESS:8500
        services:
          - node_exporter

Grafana

Grafana allows users to query, visualize, alert on and understand your metrics no matter where they are stored, supports multiple data sources and provides very powerful dashboard for displaying multiple metrics.

Installation

In docker-compose.yml:

services:
  grafana:
    image: grafana/grafana
    restart: always
    ports:
      - 3000:3000
    volumes:
      - grafana:/var/lib/grafana
volumes:
  grafana:

Grafana provides a UI at :3000 by default.

You could follow the instructions in Grafana to add data sources including Prometheus and import dashboards.

This dashboard could show system status according to the data collected by Prometheus.

References