natalie-o-perret/docker+kubernetes-notes.md

## docker+kubernetes-notes.md

      
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              docker+kubernetes-notes.md
            
          
    Docker

Some definitions


Layer: Files generated from running some command, also called intermediate images. Reused by multiple images to reduce image and size.
Image: A docker container image is created using a dockerfile (ie. build). Every line in a dockerfile will create a layer.
Container: an instance of an (read-only) image.
Docker Client: the CLI tool that allows the user to interact with the Docker Server.
Docker Server: aka Docker Daemon, the background service running on the host that manages the building, running and distributing Docker containers.

Simplest Dockerfile Ever!

# Use an existing image as a base
FROM alpine

# Download and install a dependency
RUN apk add --update redis

# Tell an image what to do when it starts as a container
CMD ["redis-server"]
Then build its image: docker build .
And run it: docker run -p 8080:8080 id-given-upon-build-completion
docker-compose

Simple Example:
version: '3'
services:
  redis-server:
    image: 'redis'
  node-app:
    restart: on-failure
    build: .
    ports:
      - "4001:8081"