Docker

Introduction to Docker example and notes

What is docker?

• https://www.itzgeek.com/wp-content/uploads/2017/05/Build-Docker-Images-with-DockerFile.png
• https://images.idgesg.net/images/article/2017/06/virtualmachines-vs-containers-100727624-large.jpg

Installation (Mac)

brew cask install docker

Terminology

• docker file (Dockerfile)
• docker image (eg. nginx:latest)
• docker container
• docker volume
• docker network
• docker registry (dockerhub, ECR)
• docker-compose

Image naming & tags

• mbarany/docker-example
• mbarany/docker-example:latest
• mbarany/docker-example:1.0
• ubuntu:18.04
• nginx:latest

Dockerfile

Documentation: https://docs.docker.com/engine/reference/builder/#from

Dockerfile Example:

FROM ubuntu:18.04
COPY . /app
RUN make /app
CMD python /app/app.py

Docker Registry

https://hub.docker.com/

• pull images

  docker pull nginx:latest

• push images

  docker push mbarany/docker-example:latest

Library

https://hub.docker.com/u/library

• Ubuntu
• Postgres
• MySQL
• Redis
• Python
• Nginx

run

docker run alpine /bin/sh
# The following subshell will run on the host (as expected)
docker run alpine echo "hi from alpine: $(uname -rs)"
docker run alpine sh -c 'echo "hi from alpine: $(uname -rs)" && echo "more stuff"'
docker run -it alpine /bin/sh
docker run -it --rm alpine
docker run -it --rm --name my-alpine alpine

• Use --rm
• Use --name <container name>

Path to a Container

1. Create Dockerfile
2. Build Dockerfile and create Image
3. Start container with a given Image

build

docker build -t mbarany/docker-example .
docker build -t mbarany/docker-example:latest .
docker build -f Dockerfile -t mbarany/docker-example:latest .

exec

docker exec -it <container> /bin/sh

logs

docker logs -f nginx
docker logs -f --tail 50 nginx

Part 2

port bindings

# Publish all
docker run --rm -d --name nginx -P nginx
# Publish list
docker run --rm -d --name nginx -p 80 nginx
docker run --rm -d --name nginx -p 9999:80 nginx

volumes

# List volumes
docker volume ls
# Map volume
docker run --rm -it --name myapp -v "$(pwd)":/app alpine
# Make it read only
docker run --rm -it --name myapp -v "$(pwd)":/app:ro alpine
# Create a volume
docker volume create foobar
docker run --rm -it --name myapp -v foobar:/app/foobar alpine

docker-compose

version: '3.4'

services:
  app:
    build: .
    depends_on:
     - db
     - redis
    volumes:
      - ./:/app
    environment:
      FOOBAR: bar
    env_file:
      - .env

  db:
    image: postgres:10-alpine

  redis:
    image: redis:alpine

https://docs.docker.com/compose/compose-file/

docker-compose up -d

Part 3

docker-compose examples

View advanced examples of docker-compose.yml files

networking

https://docs.docker.com/network/

• host
• bridge
• none

# List networks
docker network ls
# Create network
docker network create foo
# Delete network
docker network rm foo

restart policy

https://docs.docker.com/compose/compose-file/compose-file-v2/#restart https://docs.docker.com/compose/compose-file/#restart_policy

Alpine

Tiny linux distro. Perfect for a docker container base

• apk Package manager

Entrypoint VS CMD

https://stackoverflow.com/questions/21553353/what-is-the-difference-between-cmd-and-entrypoint-in-a-dockerfile/21564990#21564990

docker inspect

docker inspect mbarany/docker-example
# brew install dive
dive mbarany/docker-example

Scratch

This is where all docker images begin https://hub.docker.com/_/scratch

Other docker things

• https://github.com/veggiemonk/awesome-docker

License

Copyright 2018 Michael Barany

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.