What is Docker and why should you use it?
Hello dear friends, I hope you're well.
In this post I want to talk to you about Docker and look at what Docker is and what it's good for.
Please stay with me through the rest of the post as we look at this software.
What is Docker?
Docker is an orchestrator that helps programmers automatically run different kinds of development software in a semi-virtual environment, and beyond that it also gives us more capabilities, such as replication and fault tolerance. Below we'll look at these important features of Docker, and I'll also tell you how you can continue and go learn to use Docker.
Docker being an orchestrator means you can use it as something similar to a virtual machine and run, more or less, another operating system inside your own. Only it's not a whole other operating system like a virtual machine, just part of one. The benefit is that you no longer need to install a bunch of driver software, or sit waiting for a virtual operating system to boot and then install a bunch of programs on it from scratch. Instead, in Docker, using just an image, you can install the programs you want in an isolated environment without interfering with your current operating system. In fact, you have something prebuilt that lets you quickly run the tools you need.
Why should we use Docker?
Now let me give an example. Suppose we want to install the Postgres database on our system. Using the dedicated Postgres image, we can easily run a Docker container that includes the database we want, in exactly the version we want. This way Docker completely automatically creates this container for us, installs the database on it, applies its default settings, and it's ready for us to use.
This saves us from wrestling with how to install various tools, and it also makes things easier for our colleagues, because like us they're spared the installation hassle, and more importantly, they use exactly the same version we do. Because of this, we stay in sync with each other.
In addition, if our software needs to be installed on a particular server, we can use Docker to install it on the production server too without any hassle, so it's in sync with our own system there as well.
The things I've told you so far were about making it easier to install various tools, and they help us a great deal. But contrary to what many programmers think, Docker isn't just for these things; it can also be used for other things, some of which we'll look at below.
Another area where Docker can be used is replication. For example, say we have software on a server whose number of users has grown so much that it can't keep up anymore and has slowed down. To speed up our software, we can use Docker's replication feature, for example bring up 4 instances of our software at the same time and tell Docker to distribute the requests coming from users among these four instances. This way we're running our software in parallel and will respond to our users much faster. Of course, there's a very, very important point here that we need to pay attention to: since we're running our software in parallel, we need to make sure our program doesn't run into concurrency problems.
Another Docker feature is fault tolerance. For example, suppose that in the previous example, where we ran 4 containers of our software on the server, one of the instances hit an error and suddenly closed. If this happened to all 4 instances, our server would stop responding and the system would effectively go down, until we noticed ourselves and went and fixed and restarted it manually. But Docker's fault tolerance lets us deal with this problem: for example, when one of the programs hits an error and closes, Docker, based on the settings we give it, automatically runs our program again so the 4 containers we have go back to normal. This way there's no need for us to do anything at all, and Docker fixes the problem by itself, automatically, without our software going down for even a moment.
Having features like these really raises the quality of our software and lets us build large systems that can work at a large scale.
Docker's capabilities don't end here either, and you can do even bigger things with it. To free yourself from many problems and save your time, I recommend you definitely use Docker. And here's some good news: I've made a very complete Docker course myself, where I teach you hands-on how to use it and make your life easier. This course is on the Faranesh website (an Iranian online learning platform), where you can easily get it:
Docker course on Faranesh, produced by Hesam Gholami (in Persian)
If you have any questions about Docker or my course, I'd be happy to hear them in the comments.
All the best