Our First Work in Docker – Containerize your application
- This involves building a docker image
- Once we have build the docker image we store it in registry
- We can create containers from docker image
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Overview
- Terms
- Host: The machine (Physical/Virtual) on which docker is installed.
- Docker image: This is a packaging format which contains all the necessary stuff in it to run the application in container
- Container: This a isolated area with all the necessary stuff to run the application. we need image to create a container.
- Registry: This is store where docker images are maintained to be allowed to download and use by others. Docker Hub is default registry and generally organizations have their own private/public registries
Docker Components
- This is primary & simple version
- When we install docker, we get two major components
- client: This is a command line executable
- server/engine
History
- Docker as a organization has started adding many features into docker which were making containers fat.
- At that point of time few other companies have also launched container engines (rkt containers, …)
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Now a Group was formed called as Open Container Initiative (OCI) which started publishing specifications
- Runtime Spec
- Image spec
- Docker in its early version used to rely on linux kernel directly to create containers. The challenge when kernel’s used to be updated some versions lead to containers being impacted, to solve this problem docker created a libcontainer to manage containers
Question
- What is namespace in linux and why do we use it ?
- What is control group in linux (cgroup) in linux ?
