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Docker What, Docker? Opensource platform tool  Manages the containers Allow to build applications in a container with the libraries, binaried and dependencies run from anywhere Why Docker? portability light weight OS fast delivery(impact of light weight os) Multiple isolated OS Resource optimization Continous development and testing Architecture Docker Client Docker Host  Docker Hub(Registery) Also Docker images , Docker containers , Dcker Network and storages are contains in the architecture. Docker client is used to communicate with Docker hosts using Docker daemon is installed in Docker host. Clients are used to manage the Docker components and operations such as create, delete, pull, push, bulid, run etc. Docker client can connect to the Docker host remotly using REST API, UNIX sockets or using a network interface. Docker hub(Registery) is used to pull and push Docker images There are two types of docker hubs Docker Hub Online/Docker Hub

Changes of an peratingo system is divided in to  5 sections System changes Security changes Storage changes Network changes Application changes 1.System changes   32 bits no more in use in RHEL 7, need at least 1GB memory per logical CPU and 2GB memory to run 2.Security changes firewalld - buildin configurations /usr/lib/firewalld and /etc/firewalld SELinux can change the options FSS - Forward Secure sealing       A new mechanism to secure  systemd journal. It is disabled in default. To enable it, run the command journalctl --setup-keys. By running this "sealing key" and "verification key" are generated, the "verification key" is generated once and stored locally or has to be recorded. Identity management is used 3.Storage changes    New default file system is xfs. It allows upto 500TB comparing ext4 allows 16TB in REHL 6. It adds additional features such as best performance for most workloads and less CPU intensive. As a drawback, Shr