Here, I’ll take you through a conceptual journey from running an app on a physical machine to running it in a container.
Deploying essentially means running an app. So, I’ll just talk about running an app in the below content.
Things you have:
- Money Manager App
- Frontend App written in React
- Backend App written in Node.js
- Database - postgreSQL
- A physical machine (let’s say your laptop)
lets start!
1. Bare Metal Servers
No Abstractions
In the early days, every app ran on its own dedicated physical machine.
Problems
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space
-
cost
-
maintenance
-
wastage of resources
The machine would be running 24/7, but the app would not be using the machine’s full capacity all the time.
-
scalability
If the app needed to scale, you would have to scale the machine horizontally (buying more machines) or vertically(upgrading the existing machine) - adding more cost.
You can see that running an app on a physical machine is not efficient.
This is where virtualization comes in.
2. Virtualization
Abstraction between you and the hardware
This concept lets us run multiple digital machines (called Virtual Machines - VMs) on a single physical machine.
Virtualizes the underlying hardware - VMs have their own OS, and share the same hardware.
Who lets you do that? Hypervisor
The hypervisor is a software that creates and runs virtual machines. It manages the virtual machines’ resources and isolates them from each other.
Problems
Each VM has its own OS, which means:
- heavyweight
- consume more resources
- slower compared to running on a physical machine
I mean you just want to run an app! Why do you need a full OS for that? Is there a way to run an app without the overhead of a full OS? Is there a way to run an app in an environment that has everything it needs to run?
This is where containerization come in.
3. Containerization
Abstraction between you and the OS
Containers packages an application in such a way that it can run the same way across multiple environments.
It virtualizes the OS - containers share the same OS kernel.
Who lets you do that? Container Engine
The container engine (like Docker) is a software that creates and runs containers. It manages the containers’ resources and isolates them from each other.
Advantages
- lightweight and portable
- fast to start
- consume fewer resources
- easy to scale, doesn’t waste resources
- easy to develop apps in, apt for teams working in different environments
- more apps can run on the same hardware, than VMs
- easy for developers to work on the app
You can run more containers than VMs on a given physical machines, so technically more apps can run on the same hardware.
That’s it for now.
I hope we are clear on the journey from running an app on a physical machine to running it in a container.