For many years now, enterprise software has typically been deployed either on “bare metal” (i.e. installed on an operating system that has complete control over the underlying hardware) or in a virtual machine (i.e. installed on an operating system that shares the underlying hardware with other “guest” operating systems). Virtual machines also helped cut costs, because more VMs could be consolidated onto fewer physical machines. Legacy systems running older applications could be turned into VMs and physically decommissioned to save even more money.
VMs are not able to deliver the kind of speed, agility, and savings that fast-moving businesses are demanding.
Docker enables more efficient use of system resources Instances of containerized apps use far less memory than virtual machines, they start up and stop more quickly Save on costs of software licenses, because you need many fewer operating system instances to run the same workloads.
Docker enables faster software delivery cycles
Docker shines for micro services architecture
docker version
docker info
docker images
docker ps
docker ps -a
docker stats
docker run -it centos /bin/bash (i - interactive t - terminal)
docker run -d -t centos /bin/bash
docker exec -it centos
(Ctrl +pq to come out from container )
docker stop <container_name>
docker start <container_name>docker images and containers stored under /var/lib/docker
docker run -d -t --name <name> --hostname <container_hostname> <image_name>
example: docker run -d -t --name nginxserver --hostname nginxpod nginx
docker rm <contaienr> docker run -d -t --name nginx -p 8080:80 nginxinside a container of nginx got to /user/share/nginx/html location to update index.html
docker commit <contaner_ID> image_name:V1 - to create image out of container
docker login <Docker_hub_URL>:<port>#Docker Image Docker Containers are nothing but the runtime instance of Docker Image. `