A minimal Sensu environment with Docker

This past week, I had the pleaseure of attending Dockercon. While I was there primarily working the Sensu booth, it occurred to me that Docker presents an ideal way to demo what Sensu does, and I can quickly get an environment up without having to go through the rigmarole that I previously did using Vagrant. Now, that’s not saying that I think one tool is better than the other, but for the purposes of quick demos, Docker is more useful to me.

So let’s go over the setup.

Docker details

I’m primarily using Docker for Mac right now, since I’ve switched over from my Linux laptop. But now that I’ve covered that, let’s take a look at this little repo I’m using.

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.
├── README.md
├── assets
│   ├── hello-world-ruby.tar.gz
│   ├── helloworld-v0.1.tar.gz
│   ├── sensu-plugins-cpu-checks_4.0.0_alpine_linux_amd64.tar.gz
│   └── sensu-ruby-runtime_0.0.5_alpine_linux_amd64.tar.gz
├── config
│   ├── nginx
│   │   └── nginx.conf
│   └── sensu
│       ├── assets
│       │   ├── sensu-plugins-cpu-checks.yaml
│       │   └── sensu-ruby-runtime.yaml
│       └── checks
│           ├── check-cpu.yaml
│           └── check-disk-usage.yaml
└── docker-compose.yaml

And a look at the docker-compose file:

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version: '3'
services:
  sensu-backend:
    image: "sensu/sensu:latest"
    ports:
      - "3000:3000"
      - "2379:2379"
      - "2380:2380"
      - "8080:8080"
      - "8081:8081"
    command: "sensu-backend start"
    volumes:
      - "/tmp/sensu:/var/lib/sensu"
    hostname: sensu-backend
  sensu-agent:
    image: "sensu/sensu:latest"
    command: "sensu-agent start --backend-url ws://sensu-backend:8081 --subscriptions dev poller system linux docker --cache-dir /var/lib/sensu --namespace default --deregister true"
    links:
      - "sensu-backend:backend"
    depends_on:
      - sensu-backend
    hostname: sensu-agent
  sensu-asset-server:
    image: nginx:latest
    ports:
    - 8000:80
    volumes:
    - "./config/nginx/nginx.conf:/etc/nginx/nginx.conf"
    - "./assets:/usr/share/nginx/html/assets"
    depends_on:
    - sensu-backend
    links:
      - "sensu-backend:backend"

What we end up with here is a backend, an agent, and a local asset server (SUPER useful if you’re on 💩 wifi/internet). This means that I can quickly spin up an agent and a backend, and then drop any asset that I need to use in the assets directory and have the agent download it quickly.

This makes demos super quick to spin up, and I can scale a bunch of agents if I want to show a large number of agent containers connecting to the backend.

Cheers!