The Advantages of Using Kubernetes and Docker Together
Docker is a company that provides a container platform. Containers are a way to pack and isolate a piece of software with everything that it needs to run.
Docker is a company that provides a container platform. Containers are a way to pack and isolate a piece of software with everything that it needs to run. I mean “isolate” in the sense that containers can assign separate resources from the host where it’s running. You might be thinking this sounds pretty, but the difference is that containers are more lightweight: they don’t need another OS to make software run.
Containers let you be more agile and build secure and portable apps, which lets you save some costs in infrastructure when done well.
I know that sounds like a textbook definition, so let’s see how this is beneficial by following the day in the life of John. kubernetes online training learn more effectively.
Let’s say John decides to start his containers journey. He learns that Docker containers work with base images as their foundation to run an app. A base image and all its dependencies are described in a file called “Dockerfile.” A Dockerfile is where you define something like a recipe that you usually have in docs (or in your mind) for anyone who wants to run your app. He starts with the .NET Core app, and the Dockerfile looks like this. Take a look:
FROM microsoft/aspnetcore-build:2.0 AS build-envWORKDIR /app# Copy csproj and restore as distinct layersCOPY *.csproj ./RUN dotnet restore# Copy everything else and buildCOPY . ./RUN dotnet publish -c Release -o out# Build runtime imageFROM microsoft/aspnetcore:2.0WORKDIR /appCOPY --from=build-env /app/out .ENTRYPOINT ["dotnet", "hello.dll"]
As you can see, it’s as if you were programming. The only difference is that you’re just defining all dependencies and declaring how to build and run the app.
John needs to put that file in the root of the source code and run the following command:
docker build -t dotnetapp .
This command will create an image with the compiled code and all of its dependencies to run. He’ll only do the “build’ once because the idea is to make the app portable to run anywhere. So when he wants to run the app, only Docker needs to be installed. He just needs to run the following command:
docker run -d -p 80:80 dotnetapp
This command will start running the app on port 80 of the host. It doesn’t matter where he runs this command. As long as port 80 isn’t in use, the app will work.
John is now ready to ship the app anywhere because he’s packed it in a Docker container.
So why is this better? Well, John doesn’t have to worry about forgetting what he installed on his local computer or on any other server. Kubernetes online course will make you to learn more skills and techniques from industrial experts.
When the team grows, a new developer will rapidly start coding. When John’s company hires an operations guy, the new hire will know what exactly what’s included in the container. And if they want to do an upgrade of the framework or some dependency, they’ll do it without worrying about affecting what’s currently working.
Use Docker to pack and ship your app without worrying too much about whether the app will work somewhere else after you’ve tested it locally. If it works on your machine, it will work on others’ machines.
Use Kubernetes to deploy and scale your app
So, John now just needs to go to each of the servers where he wants to ship the app and start a container. Let’s say that, in production, he has ten servers to support the traffic load. He has to run the previous command on all the servers. And if for some reason the container dies, he has to go to that server and run the command to start it again.
Wait. This doesn’t sound like an improvement, right? It’s not much different than spinning up VMs. When something goes down, he’ll still need to manually go and start containers again. He could automate that task too, but he’ll need to take into consideration things like health checks and available resources. So here’s where Kubernetes comes into play.
Kubernetes, as their site says, “is an open-source system for automating deployment, scaling, and management of containerized applications.” but Kubernetes is the most popular one right now. Kubernetes does the container orchestration so you don’t have to script those tasks. It’s the next step after containerizing your application, and its how you’ll run your containers at scale in production.
Kubernetes will help you to deploy the same way everywhere. Why? Because you just need to say, in a declarative language, how you’d like to run containers. You’ll have a load balancer, a minimum amount of containers running, and the ability to scale up or down only when it’s needed—things that you’d otherwise need to create and configure separately. You’ll have everything you need to run at scale, and you’ll have it all in the same place.
This command will create everything that’s needed, or it will just apply an update, if there is one.
He can run the exact same command on this computer or any other environment, including production, and it will work the same way everywhere. But it’s not just that. docker and kubernetes training learn more effectively.
Kubernetes constantly checks the state of your deployment according to the yaml definition you use. So if a Docker container goes down, Kubernetes will spin up a new one automatically. John no longer has to go to each server where the container failed to start it up again; the orchestrator will take care of that for him. And there will be something monitoring the stake to make sure it’s compliant—meaning it’s running as expected—all the time.