使用Prometheus监控Docker与Ruby应用[macOS Mojave]

Prometheus是一个开源的系统监控报警工具。本文示例将Docker与Ruby应用作为其监控目标的配置方法。

配置Docker

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在daemon.json加入如下配置后重启docker。

//指定metrics采集端口， Prometheus会定时从该端口拉取数据
{
  "metrics-addr" : "127.0.0.1:9323",
  "experimental" : true
}

配置和启动Ruby应用

1. 安装Prometheus ruby客户端
   https://github.com/prometheus/client_ruby

# Gemfile
gem 'prometheus-client'

将prometheus-client添加到Gemfile后bundle install安装客户端.

2. 以中间件的形式加入rack

require 'rack'
require 'prometheus/middleware/collector'
require 'prometheus/middleware/exporter'

use Rack::Deflater
use Prometheus::Middleware::Collector
use Prometheus::Middleware::Exporter

run ->(_) { [200, {'Content-Type' => 'text/html'}, ['OK']] }

并以9100端口启动应用。

配置和启动Prometheus

将Prometheus以Docker的形式运行在本地。

1. 创建Prometheus配置文件

将以下内容保存为/tmp/prometheus.yml，作为Prometheus的配置文件

# my global config
global:
  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).

  # Attach these labels to any time series or alerts when communicating with
  # external systems (federation, remote storage, Alertmanager).
  external_labels:
      monitor: 'codelab-monitor'

# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
rule_files:
  # - "first.rules"
  # - "second.rules"

# A scrape configuration containing exactly one endpoint to scrape:
# Here it's Prometheus itself.
scrape_configs:
  # The job name is added as a label `job=` to any timeseries scraped from this config.
  # metrics_path defaults to '/metrics'
  # scheme defaults to 'http'.
# Prometheus服务
  - job_name: 'prometheus'
    static_configs:
      - targets: ['docker.for.mac.localhost:9090']
# Docker 
  - job_name: 'docker'
    static_configs:
      - targets: ['docker.for.mac.host.internal:9323']

# Ruby应用，笔者Ruby应用的端口是9100
  - job_name: "ruby-example"
    static_configs:
      - targets: ['docker.for.mac.localhost:9100']

2. 启动Prometheus
   执行如下命令，启动Prometheus

docker run -p 9090:9090 -v /tmp/prometheus.yml:/etc/prometheus/prometheus.yml prom/prometheus

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访问http://localhost:9090/targets/查看结果

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参考：
Collect Docker metrics with Prometheus
prometheus/client_ruby