there are many docker images available on hub.docker.com, we can just pull them & start running containers

	docker search <image name> -- to search the docker images from command line
	docker pull <image name> -- to pull a docker image from docker hub	

	docker images -- to display the images on your local machine
	docker history < image name > -- to know the changes done to the image
	docker inspect < image name > -- to view the detaied information in JSON output
	docker rmi <image name> -- to remove a image from local machine
	docker image prune -- to remove all unused images from local machine
	
how to run containers from a docker image 

	two ways we can run the images 
		interative mode ( -it )
		detached mode  ( -d )
	
	docker run -d nginx ( always creates new container & detaches from the terminal you are working on ( goes in background process )) 
	docker run -it nginx bash ( always creates new container & gets inside the container )
	docker ps -- to check all running containers 
	docker ps -a -- to check all running + exited/stopped containers
	
	docker stop <container id> -- to stop a container 
	docker start <container id> -- to start a stopped container 
	docker restart <container id> -- to restart a container 
	docker inspect <container id> -- to view detailed information about the continaer in JSON format
	docker rm <container id> -- to remove a stopped/exited container
	docker rm -f <container id> -- to remove a container forcefully though it is in running state 
	docker container prune -- to remove all stopped/exited containers
	
how to get inside a running container

	docker run -d nginx ( creates a new container in detached mode )
	docker ps  -- displays the running containers, note down the container id
	docker exec -it <container id> bash 

how to come out of a container
	ctrl pq ( it is mandatory to use this command always )
	
how to access the applications running inside the container from external world ( browser )
	
	services running inside a container can never be accessed direcltry, we always need to publish/expose them on to docker host while we create the containers 
	
	we need to publish/expose the services using -P (capital) OR -p (small) with in the docker run command  
	
	ex: -P ( capital ) -- docker will publish/expose the port number dynamically on docker host & maps with port running inside the cont
	
		docker run -d -P nginx -- which create a new port mapping from docker host to the service inside the container 
		docker ps -- to check the container port 
		to access : in the browser http://<docker host IP>:<exposed port>  ex: http://52.14.62.88:32768
	
		-p ( small ) -- we need to assign a port on docker host & map to the port inside the container 
		
		docker run -d -p 1234:80 nginx ( always port-on-docker-host : process-port-inside-container )
		docker ps -- to check the container port 
		to access : in the browser http://<docker host IP>:<exposed port>  ex: http://52.14.62.88:1234

===============================================================================================================================

Advanced Container commands 

limit container resources
	docker run -d --restart unless-stopped -p 8080:80 --memory 500M --memory-reservation 256M nginx
	docker run -d -P --cpus=".5" nginx

Run a docker container, overriding the system default logging driver settings:
	docker run --log-driver json-file --log-opt max-size=50m nginx

updating container network 
	docker network disconnect bridge <contid>
	docker network connect myb <contid>

	docker run -itd --net net1 alpine
	docker network connect net2 contid
	( container will be present in both net1 & net2 networks )

--restart flag: specify when the container should be automatically restarted
	1) no(default): Never restart the container
	2) on-failure: only if the container fails (exits with non-zero exit code)
	3) always: Always restart the container whether it succeeds or fails. Also start the container automatically on  daemon startup
	4) unless-stopped: Always restart the container whether it succeeds or fails, and the daemon startup, unless the container was manually stopeed