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liw71 / Fast-Docker

This repo covers containerization and Docker Environment: Docker File, Image, Container, Commands, Volumes, Networks, Swarm, Stack, Service, possible scenarios.

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Fast-Docker

This repo aims to cover Docker details (Dockerfile, Image, Container, Commands, Volumes, Docker-Compose, Networks, Swarm, Stack) fastly, and possible example usage scenarios (HowTo: Applications) in a nutshell. Possible usage scenarios are aimed to update over time.

Keywords: DockerImage, Dockerfile, Containerization, Docker-Compose, Swarm, Service, Cheatsheet

Quick Look (HowTo)

Table of Contents

Motivation

Why should we use Docker? "Docker changed the way applications used to build and ship. It has completely revolutionized the containerization world." (Ref:ItNext)

Needs

  • Installing all dependencies, setting up a new environment for SW (time-consuming every time to install environment for testing )
  • We want to run our apps on different platforms (Ubuntu, Windows, Raspberry Pi).
    • Question in our mind: What if, it does not run on a different OS?
  • CI/CD Integration Testing: We can handle unit testing, component testing with Jenkins. What if integration testing?
    • Extending Chain: Jenkins- Docker Image - Docker Container - Automatic testing
  • Are our SW products portable to carry on different PC easily? (especially in the development & testing phase)

Benefits

  • NOT needed to install dependencies/SWs again & again
  • Enables to run on different OS, different platforms
  • Enables consistent environment
  • Enables more efficient use of system resources
  • Easy to use and maintain
  • Efficient use of the system resources
  • Isolate SW components
  • Enables faster software delivery cycles
  • Containers give us instant application portability.
  • Enables developers to easily pack, ship, and run any application as a lightweight, portable, self-sufficient container
  • Microservice Architecture (Monolithic Apps to MicroService Architecture, e.g. Cloud Native App)

(Ref: Infoworld)

Problems Docker does not solve

  • Docker does NOT fix your security issues
  • Docker does NOT turn applications magically into microservices
  • Docker isn’t a substitute for virtual machines

(Ref: Infoworld)

What is Docker?

  • Docker is a tool that reduces the gap between Development/Deployment phase of a software development cycle.
  • Docker is like VM but it has more features than VMs (no kernel, only small app and file systems, portable)
    • On Linux Kernel (2000s) two features are added (these features support Docker):
      • Namespaces: Isolate process.
      • Control Groups: Resource usage (CPU, Memory) isolation and limitation for each process.
  • Without Docker, each VM consumes 30% resources (Memory, CPU)

image (Ref: Docker.com)

Architecture

image (Ref: docs.docker.com)

Installation

Docker Engine (Deamon, REST API, CLI)

  • There are mainly 3 components in the Docker Engine:
    • Server is the docker daemon named docker daemon. Creates and manages docker images, containers, networks, etc.
    • Rest API instructs docker daemon what to do.
    • Command Line Interface (CLI) is the client used to enter docker commands.

image (Ref: Docker.com)

Docker Registry and Docker Hub

image

App: Running Docker Free Local Registry, Tagging Container, Pushing to Local Registry, Pulling From Local Registry and Deleting Images from Local Registry

Docker Command Structure

  • docker [ManagementCommand] [Command]
docker container ls -a
docker image ls
docker volume ls
docker network ls
docker container rm -f [containerName or containerID]

image

image

Docker Container

image (Ref: docker-handbook-borosan)

  • When we create the container from image, in every container, there is an application that is set to run by default app.
    • When this app runs, container runs.
    • When this default app finished/stopped, container stopped.
  • There could be more than one app in docker image (such as: sh, ls, basic commands)
  • When the Docker container is started, it is allowed that a single application is configured to run automatically
docker container run --name mywebserver -d -p 80:80 -v test:/usr/share/nginx/html nginx
docker container ls -a
docker image pull alpine
docker image push alpine
docker image build -t hello . (run this command where “Dockerfile” is)
(PS: image file name MUST be “Dockerfile”, no extension)
docker save -o hello.tar test/hello
docker load -i <path to docker image tar file>
docker load -i .\hello.tar

Goto: App: Creating First Docker Image and Container using Docker File

Docker Container: Life Cycle

image (Ref: life-cycle-medium)

e.g. [imageName]=alpine, busybox, nginx, ubuntu, etc.
docker image pull [imageName]
docker container run [imageName]
docker container start [containerId or containerName]
docker container stop [containerId or containerName]
docker container pause [containerId or containerName]
docker container unpause [containerId or containerName]

Docker Container: Union File System

  • Images are read only (R/O).
  • When containers are created, new read-write (R/W) thin layer is created.

image (Ref: docs.docker.com)

Docker Volumes: Why Volumes needed?

  • Containers do not save the changings when removed, if there is not any binding to volume/mount.
  • For persistence, volumes/mounts MUST be used.
  • e.g. Creating log file in the container. When the container is removed, log file also removed with container. So volumes/binding mounts MUST be used!

image (Ref: udemy-course:adan-zye-docker)

Docker Volumes/Bind Mounts

  • Volumes and Bind Mounts used for logs, inputs, outputs, etc..
  • When volumes bind to directory in the container, this directory and volume are synchronised.
docker volume create [volumeName]
docker volume create test
docker container run --name [containerName] -v [volumeName]:[pathInContainer] [imageName]
docker container run --name c1 -v test:/app alpine

Goto: App: Binding Volume to the Different Containers

Bind Mount

docker container run --name [containerName] -v [pathInHost]:[pathInContainer] [imageName]
docker container run --name c1 -v C:\test:/app alpine

image (Ref: Docker.com)

Goto: App: Binding Mount to Container Goto: App: Transferring Content between Host PC and Docker Container

Docker Network

  • Docker containers work like VMs.
  • Every Docker containers have network connections
  • Docker Network Drivers:
    • None
    • Bridge
    • Host
    • Macvlan
    • Overlay

Docker Network: Bridge

  • Default Network Driver: Bridge (--net bridge)
docker network create [networkName]
docker network create bridge1
docker container run --name [containerName] --net [networkName] [imageName] 
docker container run --name c1 --net bridge1 alpine sh
docker network inspect bridge1
docker container run --name c2 --net bridge1 alpine sh
docker network connect bridge1 c2
docker network inspect bridge1
docker network disconnect bridge1 c2
  • Creating new network using customized network parameters:
docker network create --driver=bridge --subnet=10.10.0.0/16 --ip-range=10.10.10.0/24 --gateway=10.10.10.10 newbridge

image (Ref: Docker.com)

Docker Network: Host

  • Containers reach host network interfaces (--net host)
docker container run --name [containerName] --net [networkName] [imageName] 
docker container run --name c1 --net host alpine sh

image (Ref: Docker.com)

Docker Network: MacVlan

  • Each Container have own MAC interface (--net macvlan)

image (Ref: Docker.com)

Docker Network: Overlay

  • Containers which work on different PC/host, can work like same network (--net overlay)

image (Ref: Docker.com)

Port Mapping/Publish:

  • Mapping Host PC's port to container port
-p [hostPort]:[containerPort], --publish [hostPort]:[containerPort] e.g. -p 8080:80, -p 80:80
docker container run --name mywebserver -d -p 80:80 nginx

Docker Log

  • Docker Logs show /dev/stdout, /dev/stderror
docker logs --details [containerName]

image

Docker Stats/Memory-CPU Limitations

image

image

image

Docker Enviroment Variables

image

Docker File

image

Sample Docker Files

FROM python:alpine3.7
COPY . /app
WORKDIR /app
RUN pip install -r requirements.txt
EXPOSE 5000
CMD python ./index.py

FROM ubuntu:18.04
RUN apt-get update -y
RUN apt-get install default-jre -y
WORKDIR /myapp
COPY /myapp .
CMD ["java","hello"]
  • Multistage Docker File (Creating temporary container):
    • In the example, JDK (Java Development Kit) based temporary image (~440MB) container is created for compilation.
    • Compiled files are copied into JRE (Java Runtime Environment) based image (~145MB). Finally, we have only JRE based image.
FROM mcr.microsoft.com/java/jdk:8-zulu-alpine AS compiler
COPY /myapp /usr/src/myapp
WORKDIR /usr/src/myapp
RUN javac hello.java

FROM mcr.microsoft.com/java/jre:8-zulu-alpine 
WORKDIR /myapp
COPY --from=compiler /usr/src/myapp .
CMD ["java", "hello"]

Docker Image

  • Create Image using Dockerfile
docker image build -t hello . (run this command where “Dockerfile” is)
(PS: image file name MUST be “Dockerfile”, no extension)
docker image pull [imageName]
docker image push [imageName]
docker image tag [imageOldName] [imageNewName]
(PS: If you want to push DockerHub, [imageNewName]=[username]/[imageName]:[version])
docker save -o hello.tar test/hello
docker load -i <path to docker image tar file>
docker load -i .\hello.tar

image

Goto: App: Creating First Docker Image and Container using Docker File

Docker Compose

  • Define and run multi-container applications with Docker.
  • Easy to create Docker components using one file: Docker-Compose file
  • It is yaml file that defines components:
    • Services,
    • Volumes,
    • Networks,
    • Secrets
  • Sample "docker-compose.yml" file:
version: "3.8"

services:
  mydatabase:
    image: mysql:5.7
    restart: always
    volumes: 
      - mydata:/var/lib/mysql
    environment: 
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress
    networks:
      - mynet
  mywordpress:
    image: wordpress:latest
    depends_on: 
      - mydatabase
    restart: always
    ports:
      - "80:80"
      - "443:443"
    environment: 
      WORDPRESS_DB_HOST: mydatabase:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
      WORDPRESS_DB_NAME: wordpress
    networks:
      - mynet
volumes:
  mydata: {}
networks:
  mynet:
    driver: bridge
  • After saving file as "docker-compose.yml", run following commands where docker-compose file is, to create containers, volumes, networks:
docker-compose up -d
docker-compose down

Goto: App: Docker-Compose File - Creating 2 Different Containers: WordPress Container depends on MySql Container

Docker Swarm

One of the Container Orchestration tool:

  • Automating and scheduling the
    • deployment,
    • management,
    • scaling, and
    • networking of containers
  • Container Orchestration tools:
    • Docker Swarm,
    • Kubernetes,
    • Mesos

image (Ref: udemy-course:adan-zye-docker)

Docker Stack / Docker Service

  • With Docker Stack, multiple services can be created with one-file.
  • It is like Docker-Compose file but it has more features than Docker-compose file: update_config, replicas.
  • But it is running on when Docker Swarm mode is activated.
  • Network must be overlay.

Creating, Listing, Inspecting

docker service create --name testservice --replicas=5 -p 8080:80 nginx
docker service ps testservice (listing running containers on which nodes)
docker service inspect testservice

Scaling

docker service scale testservice=10 (scaling up the containers to 10 replicas)

Updating

docker service update --detach --update-delay 5s --update-parallelism 2 --image nginx:v2 testservice (previous state: testservice created, now updating)
docker service update --help (to see the parameters of update)

Rollbacking

docker service rollback --detach testservice (rollbacking to previous state)

image

Goto: App: Creating Docker Swarm Cluster With 5 PCs using PlayWithDocker : 3 x WordPress Containers and 1 x MySql Container using Docker-Compose File

Play With Docker

image

Docker Commands Cheatsheet

Goto: Docker Commands Cheatsheet

Other Resources :

References

About

This repo covers containerization and Docker Environment: Docker File, Image, Container, Commands, Volumes, Networks, Swarm, Stack, Service, possible scenarios.

License:MIT License