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1. HOW TO USE DOCKER AND KUBERNETES HOW TO
2. HOW TO USE DOCKER AND KUBERNETES ARCHIVE
3. HOW TO USE DOCKER AND KUBERNETES PORTABLE
4. HOW TO USE DOCKER AND KUBERNETES SOFTWARE
5. HOW TO USE DOCKER AND KUBERNETES CODE

The only difference is that you’re just defining all dependencies and declaring how to build and run the app. # Copy csproj and restore as distinct layersĪs you can see, it’s as if you were programming. Take a look: FROM microsoft/aspnetcore-build:2.0 AS build-env NET Core app, and the Dockerfile looks like this.

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 learns that Docker containers work with base images as their foundation to run an app. Let’s say John decides to start his containers journey. 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.

HOW TO USE DOCKER AND KUBERNETES PORTABLE

Containers let you be more agile and build secure and portable apps, which lets you save some costs in infrastructure when done well.

HOW TO USE DOCKER AND KUBERNETES SOFTWARE

You might be thinking this sounds pretty similar to VMs, but the difference is that containers are more lightweight: they don’t need another OS to make software run. I mean “isolate” in the sense that containers can assign separate resources from the host where it’s running. Containers are a way to pack and isolate a piece of software with everything that it needs to run. Use Docker to pack and ship your appĭocker is a company that provides a container platform. The good news is that that’s where Docker and Kubernetes come into play. We all wish deployments could be as boring as pushing a button. Maybe John even has to spend a whole weekend doing deployments and fixing all sorts of broken things. That’s hard to do.Įven having automation in place, deployments might be too complex or painful. He has to work with production-like environments to ease deployments and reduce risk. But when we’re talking about production, things get risky. Now, he can screw things up in other environments too and then fix it, and that’s okay.

HOW TO USE DOCKER AND KUBERNETES CODE

He’ll still need to deploy changes in code and any dependencies to other environments. And then he has to somehow organize all the different versions of those VM snapshots. Why? Because every time something changes, he has to take a new snapshot. That way, he can isolate all dependencies and avoid affecting any existing apps and their dependencies One solution could be for him to work with virtual machines (VMs). It’s kind of hard to remember all the steps when we’re in a rush. The struggle becomes even bigger when he has to push a new change after doing all of that to another environment. When something’s not working, he just installs, uninstalls, updates, or removes until finally things get back up and running. The problem is when things aren’t compatible with what he’s installed. He struggles every time a new version of the language, framework, or library comes out and he has to run an upgrade. John’s a developer working for a startup, and he’s responsible for deploying his code to a live environment. For practical purposes, we’ll talk about the fictional developer John Smith. Then I’ll explain how these two technologies can help. So let me start with a typical day in the life of someone who struggles through every deployment.

How does one explain this? How do images get "registered" in the kubernetes cluster? Why couldn't crictl import the image? I might post another issue to ask that.Everything starts with your local environment They are actually the same as suggested in the crictl github documentation However, when following these steps, my image is finally recognized as an existing local image in kubernetes. I used crictl pull app:test and it showed the following error message:įATA pulling image failed: rpc error: code = Unknown desc = failed to pull and unpack image "docker.io/library/app:test": failed to resolve reference "docker.io/library/app:test": pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed.

However, trying to import my local image through crictl didn't seem to work either. It should now appear when you run sudo crictl images.Īs suggested, I tried listing images with crictl and my app:test did not appear. You can do that with the docker save or ctr image export commands.Ģ- Use sudo ctr -n=k8s.io images import myimage.tar while in the same directory as thearchived image to add it to containerd in the namespace that kubernetes uses to track it's images.

HOW TO USE DOCKER AND KUBERNETES ARCHIVE

TLDR: these steps, which are also described in the crictl github documentation:ġ- Once you get the image on the node (in my case, a VM), make sure it is in an archive (.tar). One can do so with a combination of crictl and ctr, if using containerd.