Docker Hands-On

In this hands on activity you will learn how to use Docker to pull and run images for standing up and testing out systems. You’ll also learn how to use Containerize a basic web site. You’ll also learn how to use docker-compose to bring up a semi-complex web application.

Part 1 Pulling an image

1. Use the docker hub to pull down the ghost image with the alpine tag
   • https://hub.docker.com
2. Run the image you just pulled down and map it to a local port, you can use the instructions found on the ghost docker hub page under the section Custom Port.
   Please note you will need to set the url environment variable for ghost to work properly, you can see instructions under the Configuration section. If you set the Custom Port to the port specified in the Custom Port section your url will be http://localhost:3001.

Part 2 Creating a custom docker image.

1. Create a Dockerfile FROM the nginx:alpine image.
2. Download the file to use for the demo: https://raw.githubusercontent.com/CalvinRodo/cicdepresentations/master/example/index.html Linux users can run the following command to download the file wget https://raw.githubusercontent.com/CalvinRodo/cicdepresentations/master/example/index.html you need to download it to the same location as your Dockerfile. This should work on a mac but you might have to run brew install wget first. It should also work on a windows machine in a Git Bash prompt, otherwise you’ll have to download it by hand, honestly I’ve never bothered to find out if you can do it on windows.
3. COPY the index.html to /usr/share/nginx/html/
4. Build the image and tag it with example:1
5. Run the Image and map the internal port 80 to external port 1337 making sure to clean up the image when you are down with --rm
6. Navigate to http://localhost:1337

Part 3 Connecting two applications together using Docker Compose

1. Copy the text at the bottom of this lesson to a docker-compose.yml file.
2. Download the following seed file for the database: https:// https://raw.githubusercontent.com/CalvinRodo/cicdepresentations/master/example/seed.sql and place it in a postgres-seed folder below the docker-compose.yml file.
3. Run docker-compose up to run your database and navigate to http://localhost:8081 to see your brand spanking new seeded Postgres database.

version: '3'
services:
  postgres-database:
    container_name: postgres-database
    restart: always
    image: postgres:alpine
    ports:
      - 5432:5432
    volumes:
      - $HOME/docker/volumes/postgres:/var/lib/postgresql/data
      - ./postgres-seed:/docker-entrypoint-initdb.d #run these scripts on first container creation
    environment: 
      - POSTGRES_PASSWORD=docker
  pgweb:
    container_name: pgweb  # optional
    restart: always  # optional
    image: sosedoff/pgweb
    ports: 
      - "8081:8081" 
    links: 
      - postgres-database:db  # my database container is called postgres, not db
    environment:
      - DATABASE_URL=postgres://postgres:docker@db:5432/postgres?sslmode=disable
    depends_on:
      - postgres-database # my database container is called postgres, not db