10,000 Feet overview of Docker

WHY DO WE NEED DOCKER? WHAT PROBLEMS DOES IT SOLVE?

We developers usually store our code in (Source Version Repository) such as Git. We need to bring this code to different environments such as DEV, QA, UAT, Prod.

For Example: If we have 8 to 10 dependencies in our code and run our code in DEV, my code may work in DEV but not in QA environment because the dependency version we use may differ from DEV to QA. So, we face this issue.

So, we take our code from Git and build it as an Artifact. This single Artifact can be applied on each and every environments such as DEV, QA, UAT, Prod.

The Strategy we use here is “BUILD ONCE SHIP MANY”. This is the principle of Docker.

Docker also helps SCALING our application. Without Docker the time taken to Scale the application is huge. Docker solves this because it is LIGHT WEIGHT. If we run the application in another port, within few seconds the application starts receiving the traffic.

FEATURES OF DOCKER:

1. Consistent Deployments.
2. Build once ship many.
3. Single Artifact (Docker Image)
4. Light Weight
5. Secure
6. Microservices
7. Polyglot
8. Scaling

TYPES OF VIRTUALIZATIONS:

1. Hardware Level Virtualization
2. OS Level Virtualization

Docker Comes under OS Level of Virtualization.

It runs on top of an Operating System. So, Docker doesn’t have the bulkiness of the OS.

Docker supports different distributions of Linux, Windows and Mac.

NAMESPACE AND CONTROL GROUPS:

We can run containers using Namespace and Control Groups.

These Namespace and Control Groups powerups the Containers and Container Images

NAMESPACE: Namespace enables Process Isolation

CONTROL GROUPS: Limits and Isolates Resource usage.

CONTAINER RUN TIME ENGINE:

Container run time engine is a Software Component which enables us to create containers and manage them across multiple compute nodes.

Docker is the most widely used container run time engine.