Fast-Docker

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

Keywords: Docker-Image, Dockerfile, Containerization, Docker-Compose, Docker-Volume, Docker-Network, Docker-Swarm, Service, Cheatsheet.

Quick Look (HowTo: LABs)

LAB-01: Creating First Docker Image and Container using Docker File
LAB-02: Binding Volume to the Different Containers
- LAB-02.1: Binding Mount to the Container
LAB-03: Docker-Compose File - Creating 2 Different Containers: WordPress Container depends on MySql Container
LAB-04: Creating Docker Swarm Cluster With 5 PCs using PlayWithDocker : 3 x WordPress Containers and 1 x MySql Container using Docker-Compose File
LAB-05: Running Docker Free Local Registry, Tagging Image, Pushing Image to the Local Registry, Pulling Image From Local Registry and Deleting Images from Local Registry
LAB-06: Transferring Content between Host PC and Docker Container
LAB-07: Creating Docker Container using Dockerfile to Build C++ on Ubuntu18.04
LAB-08: Creating Docker Container using Dockerfile to Build C++ on Windows
LAB-09: Docker Configuration (Proxy, Registry)
Docker Commands Cheatsheet

Motivation
What is Docker?
Play With Docker
Docker Commands Cheatsheet
Other Useful Resources Related Docker
References

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)
Developing, testing, maintenance of code as one Monolithic App could be problematic when the app needs more features/services. It is required to convert one big monolithic app into microservices.

Benefits

NOT needed to install dependencies/SWs again & again
Enables to run on different OS, different platforms
Enables a 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 the Development/Deployment phase of a software development cycle.
Docker is like a 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% of resources (Memory, CPU)

(Ref: Docker.com)

Architecture

(Ref: docs.docker.com)

Installation

Linux: Docker Engine
- https://docs.docker.com/engine/install/ubuntu/
Windows: Docker Desktop for Windows
- WSL: Windows Subsystem for Linux,
- WSL2: virtualization through a highly optimized subset of Hyper-V to run the kernel and distributions, better than WLS.
  - https://docs.docker.com/docker-for-windows/install/
Mac-OS: Docker Desktop for Mac
- https://docs.docker.com/docker-for-mac/install/

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.

(Ref: Docker.com)

Docker Registry and Docker Hub

https://hub.docker.com/

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]

Docker Container

(Ref: docker-handbook-borosan)

When we create the container from the image, in every container, there is an application that is set to run by default app.
- When this app runs, the container runs.
- When this default app finishes/stops, the container stops.
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

(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.

(Ref: docs.docker.com)

Docker Volumes: Why Volumes needed?

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

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

Docker Volumes/Bind Mounts

Volumes and binding mounts must be used for saving logs, output files, and input files.
When volumes bind to the directory in the container, this directory and volume are synchronized.

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

(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 container has 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 a 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

(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

(Ref: Docker.com)

Docker Network: MacVlan

Each Container has its own MAC interface (--net macvlan)

(Ref: Docker.com)

Docker Network: Overlay

Containers that work on different PCs/hosts can work as the same network (--net overlay)

(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