namkatcedrickjumtock / docker

docker-crash-course

An Image:

Images are like blue print for containers and they contained the following inside them :-

• Runtime enviroment
• application code
• any dependency
• extra configurations (Env variables)
• commands

NB:- Images are Read only meaning once you created an image it can't not be change, if a change is made a new image needs to be build for that change :

Containers

This are runable intances of those images. or can they can seen as isolated process. (container are also process).

• Containers runs what's outline in the image file.

List of Docker images can be viewd with: docker images

Building an Image

images are Read only: meaning it can't changes onces it has been build

docker build -t <name of image> <location>
 
// Example: Docker build -t myApp .

Eunning * Stoping Containers

• Running Container

images are run on containers

   // this command creates a new container and run it
docker run --name <container name> <image name >

 every additional flag cames before the image name

example: docker run --name app1_c -p 4000:4000 -d myApp

To see running processes (containers)

docker ps  
docker ps -a // list all containers

• Docker containers can also be run specifying their name, port number if it was expose in the docker config file.

  For example:

  docker run --name <containerName> -p <define port in local machine>:<port in container>
  -d <name o image>.   
  
  docker run --name <containerName> -p 4000:4000 -d my App 
  

• Starting Container

docker start <nameOf container> 
docker stop <nameOf container> -f // to forcely closed it even it's running

Layer caching in Docker

• improving caching can be done by copying the package.json before copying the source code into the working dir

COPY package.json . 

Deleting Containers and Images

• Deleting Containers:

// deleting containers
  docker container rm name/id of container

//deleting images
  docker image rm name/id of image

// deleting more than one container
  docker container rm name/id of container 1  container 2 container 3 .......

// deleting more than one image
  docker image rm name/id of image 1  image 2 image 3 .......

Delete All Containers and Images in the SYSTEM

docker system prune -a  // take caution

Specifying image version

docker build -t node-app:v1 .    // node-app could have many versions

Docker Composer

THe docker composer file defines the configuration for all the services (images) in a project.

dokcer-compose runs the docker composer file with all the services inside