0_Docker_Ansible_mucking_about.md

Messing with Ansible and Docker

Nobody can remember how to use Docker, it is far too confusing. So here are some hints.

sudo docker build -t simple_flask:dockerfile .
sudo docker run -p 5000:5000 simple_flask:dockerfile python hello.py

My actual intention is to learn Ansible. But in order to run Ansible you need Docker, unless you happen to have a rackful of machines at your disposal which I do not.

Basic tinkering

Look at these instructions to install Ansible properly. More Ansible stuff here but it does not talk about using Docker. Wait, this one might work. Honorable mention for 1 and 2.

Working from this page, I have started to make Ansible do some things. Here we start and then stop three HTTP servers.

sudo ansible-playbook docker_go.yml

curl http://127.0.0.1:5000/   ==> value1
curl http://127.0.0.1:5001/   ==> value2
curl http://127.0.0.1:5002/   ==> value3

sudo ansible-playbook docker_stop.yml

So that is pretty cool already, and I know Ansible has a bunch more stuff like applying names to groups of machines (webserver, database, etc) so that you can run bunches of commands on them. Slick.

Using Ansible to set up SSH communications

• https://docs.ansible.com/ansible/latest/modules/authorized_key_module.html
• https://www.hashbangcode.com/article/ansible-ssh-setup-playbook
• https://hvops.com/articles/ansible-post-install/

docker_go.yml

---
- hosts: localhost
  tasks:
  - name: Pull Ubuntu image
    docker_image:
      name: ubuntu

  - name: Build simple Flask server
    docker_image:
      path: .
      name: simple_flask
      tag: 0.1

  - name: Create Flask server container1
    docker_container:
      name: my-flask1
      image: simple_flask:0.1
      ports:
        - "5000:5000"
      env:
        KEY: value1
      command: python hello.py

  - name: Create Flask server container2
    docker_container:
      name: my-flask2
      image: simple_flask:0.1
      ports:
        - "5001:5000"
      env:
        KEY: value2
      command: python hello.py

  - name: Create Flask server container3
    docker_container:
      name: my-flask3
      image: simple_flask:0.1
      ports:
        - "5002:5000"
      env:
        KEY: value3
      command: python hello.py

docker_stop.yml

---
- hosts: localhost
  tasks:
    - name: Remove Flask server container1
      docker_container:
        name: my-flask1
        state: absent

    - name: Remove Flask server container2
      docker_container:
        name: my-flask2
        state: absent

    - name: Remove Flask server container3
      docker_container:
        name: my-flask3
        state: absent

Dockerfile

FROM ubuntu
Maintainer Will

RUN apt-get update
RUN apt-get install -y python python-pip wget
RUN pip install Flask

ADD hello.py /home/hello.py

WORKDIR /home

hello.py

import os
from flask import Flask
from werkzeug import serving

app = Flask(__name__)

@app.route("/")
def hello():
  return "Hello World! This is Flask ({0}).\n".format(os.environ.get("KEY"))

serving.run_simple("0.0.0.0", 5000, app)