Containers contd…

• Lets run a java based application
• To run a java based application we need java to be installed

Physical System

• We have used a springpetclinic application and deployed into physical system
  

Virtual Machine

• Lets use Azure To create a linux (Ubuntu) and setup this application

Container

• We used docker playground and used an existing image to create a container

What should i run in a contaner

• Ideally run the server side components in a container.

How is container working at a high level

• Docker when installed on a larger note has two major components
  • client:
    • This is a command line tool which can interact with daemon/engine
  • daemon/engine:
    • This is responsible of container management
• Users execute docker commands using client and client interacts with daemon to get the job done

Creating a container

• Command docker run nginx -d means create a container, lets examine what happens now
  1. client sends request to daemon/engine
  2. daemon checks the local repo for the image, if not found tries to download from registry and even if not found throws error
  3. once the image is available a container is created using image and allocating resources (cpu, ram, ntework)
• Registry: A registry is collection of container images and each container is represented as repository.
  • container image has a repo name and version which is called as tag.
  • docker image <repo-name>:<tag>
  • if u dont pass tag latest is its default value
  • when we said docker run nginx => docker run nginx:latest
• Repo names have conventions depending on which registry you are using
• docker hub is the default registry.
• Other registries are also available
  • artifactory
  • azure container registry
  • aws elastic container registry
  • …
• Docker hub convention
  • official images: they directly have names
    • nginx
  • Trusted Partner: This is an organization trusted by docker publishing images
  • your(account) images: These are repos built by us <account-name>/<app-name> shaikkhajaibrahim/spc-gcp

First steps into docker/containers

• Containerize applications which is ensuring your application has a image (docker image/container image).