Why container and how that is different from Virtual Machine
We tried to understand What is Docker? Why is it so popular? Now let’s try to understand how the container works.
Why Container?
Yes, I believe that’s the most important question we should understand first. We have our local system to build an application. We can have Development, Test, and Production environments where we need to deploy our applications sequentially. What would be the possible steps involved to get an application deployed in different environments
- build and package the application codes
- Procure a standalone server or virtual machine to get the package deployed
- Install required framework libraries
- Deploy the application package
The next big question is how sure we are that the application will run without any issues in the new environment. I believe that is a very difficult question to answer and depends on technology, framework, programming language, etc.
What if we build the package in the Windows system, will that run in a Linux environment? Again another tough question.
If I need to run multiple versions of a framework for different applications, will a single server or virtual machine allow that? If not, we might not be able to fully utilize the resources of a system or end up with multiple servers or virtual machines impacting project costs.
For large applications, we may need to follow microservices architecture allowing us to build different components in different frameworks and technologies. How can we run multiple microservices with a diversified technology stack and optimize system resource utilization?
Virtual machines may give us some relief over standalone servers for the diversified technology stack or framework version issue but will not be able to resolve all the points we discussed.
As we can see in the diagram
- A standalone Server may end up with unutilized resources, framework version conflict, and high bootup or start time
- Virtual Machine may help on framework version conflict but it will again utilize more system resources for Host OS, and multiple Guest OS, and also it will have high bootup or start time as operating systems need to be started
- Docker helps us to overcome all these drawbacks as it will utilize Host OS, does not require Guest OS but still separates different framework libraries/versions for different applications. All applications will use the same infrastructure resources via Host OS.
- Docker Daemon is operating system specific. That will allow running containers independent of OS and environment
Hope this helps to understand how Docker or container works. We will dig deeper into all these topics in more detail.
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