docker.txt

docker --version // to check docker version
docker run hello-world // to run an image in a container. if not present it will pull from docker hub
docker run --name DragonEmperor9480 <image_name>// to specifically name a container
docker run -it <image_name> //to run the docker container in interactive mode and terminal mode
docker run -d <image_name> // run it in background
docker attach <container_id> //attach back to container 
docker run <image_name> sleep 100 // let the container run for specific time before it exits
docker pull <container> //only pull the container not run it
docker ps //list the running containers
docker ps -a //list all the containers
docker rm <container_id or name> //to remove the container
docker images // to list all the images
docker rmi <image_name> // delete the image
docker run ubuntu cat /etc/*release* // run the command inside ubuntu like executing a single command
docker run ubuntu 16:04 // here ":" is called a tag to use a specific version of a software
docker log <container_id or name> // to check logs of a container
docker stop <container_id> // to stop a running container
docker inspect // to check information about docker container
docker history
docker build Dockerfile -t DragonEmperor/my-custom-app // cmd to build a custom docker image

docker run --cpu=.5 ubuntu // dosent let the container take more than 50% of cpu
docker run --memory=100m ubuntu //dosent let the container use more than 100MB
docker volume create data_volume //creates a persistent volume where we can store data on the host machine

docker run -v data_volume:/var/lib/mysql mysql //mounts the above created colume to container
docker run -v /data/mysql:/var/lib/mysql mysql //can mount any dir by specifiying full name of it
//the above command is old way the new way is as follows


//the above two commands are old way the new command is as follows:
docker run \ --mount type=bind,source=/data/mysql,target=/var/lib/mysql mysql

--Docker Storage
the data of docker is stored in:
/var/lib/docker:
	-aufs
	-containers
	-image
	-volumes

--Storage Drivers
AUFS
ZFS
BTRFS
Device Manager
Overlay
Overlay2

--DOCKER NETWORKS
docker network ls // list the docker networks
docker network inspect bridge // bridge here is the name of the network we are inspecting
--Default Networks
Bridge -> docker run ubuntu
none-> docker run ubuntu --network=none
host->docker run ubuntu --network=host

--User-Defined Networks

docker network create \
	--driver bridge \
	--subnet 182.18.0.0/16
	custom-isolated-network

--Example: Create a new network named wp-mysql-network using the bridge driver. Allocate subnet 182.18.0.0/24. Configure Gateway 182.18.0.1

soln: docker network create --driver bridge --subnet 182.18.0.0/24 --gateway 182.18.0.1 wp-mysql-network

Inspect the created network by docker network inspect wp-mysql-network

--Example: Deploy a mysql database using the mysql:5.6 image and name it mysql-db. Attach it to the newly created network wp-mysql-network


Set the database password to use db_pass123. The environment variable to set is MYSQL_ROOT_PASSWORD.

soln: docker run --name mysql-db  -e MYSQL_ROOT_PASSWORD=db_pass123 --network wp-mysql-network mysql:5.6


--Container Orchestration
Container Orchestration allows you to run multiple thousands of instances in a single command. can also scale up and scale down based on the load.

--Docker Swarm
Combines multiple Docker machines together in a single cluster

for swarm manager: docker swarm init
for node worker: docker swarm join --token <token>

docker service create --relicas=3 my-web-server

we can have multiple manager nodes
a single manager node can be allowed to make decisions, its called leader.

--Raft  Consensys algorithm
it uses random timers for initiating requests.
the first one to finish the timer sends out a request, requesting permisson to be the leader.the other managers on reciving the request responmd with their role.
then the leader is decided.

--Quorum
it is defined as the minimum number of members in assembly that must be present in any of the meeting.
Formula: (N+1)/2 where N is number of managers.

Fault Tolerance of N = (N-1)/2

usually docker dosent recommend no more than 7 managers

--Docker Compose
https://docs.docker.com/compose/
https://docs.docker.com/engine/reference/commandline/compose/
https://github.com/dockersamples/example-voting-app

--Docker Engiene
it is referred to the host with Docker installed on it.
mainly 3 components are installed
-Docker CLI
-Rest API
-Docker Daemon


Docker CLI can run on a different machine too,
the command example for it is: docker -H=remote-docker-engiene:2375

docker exec <container_id> ps -eaf // lists all the processes of that specific container

--Docker Info
docker info //lists all the information about the docker installed on the system
docker info | more // lists more info on docker

--Docker History
If you would like to know how a docker image is built you can use following command.
docker history <image_id>


--Docker Service
docker service ls // list the services
docker service create --replicas 3 my-web-server
docker service create --mode global my-antivirus
docker service update <container_name> replicas 4 // increase replicas