I am new to the world containers, docker, kubernetes and I am investigating requirements for implementing a my middleware distributed project. I took some key container courses with Docker and Kubernetes.
But I would like to ask for those who have more experience, in a production environment (or just execution and instantiation of modules, where each module would be a container) what would be the dependencies to execute a container?
Is it mandatory for me to have the dependency package for docker and docker itself installed for this? To just raise the pods and services with Kubernetes is it also mandatory to have kubectl installed on my host?
Note: For local development and deployment using google cloud I have already done some testing and I know it is necessary.
To Setup docker on your system you need below things
if you are going to setup K8s with docker
docker-ce/docker
kubelet
kubectl
curl & wget
if you are going to setup k8s with minikube
you will need minikube
virtualenv
I feel you need to be more specific what exactly you wanted to know.
There are multiple container technologies are existing currently. To install docker specifically your linux machine should have kernel version > 3.10.
If you want to install Kubernetes on your linux machines
you need to modify OS level things.(like firewall,swap etc)
you need to install one of the container run time & other kubernetes packages(kubelet kubeadm kubectl ) then setup container networking.
Here you can find clear instructions to install kuberentes via Kubeadm
Related
I'm working on a system that spins up pods in k8s for user to work in for a while. They'll be running code, modifying files, etc. One thing I'd like to do is be able to effectively "export" their pod in it's modified state. In docker I'd just docker commit && docker save to bundle it all to a tar, but I can't see anything at all similar in the kubernetes api, kubectl, nor client libs.
Short answer: No, Kubernetes doesn't have an equivalent to docker commit/save.
As Markus Dresch mentioned in the comment:
kubernetes orchestrates containers, it does not create or modify them.
Kubernetes and Docker are 2 different tools for different purposes.
Kubernetes, also known as K8s, is an open-source system for automating deployment, scaling, and management of containerized applications.
Docker is a set of platform as a service products that use OS-level virtualization to deliver software in packages called containers.
You can find more information about Pull, Edit, and Push a Docker Image here.
I have a Intel Atom Dual Core with 4 GB RAM left over and want to use it to run docker images.
What possible solutions are there for such a local installation? I already found MicroK8s which looks promising, yet wondering which other alternatives there are. Is there maybe a complete distribution focused on only running docker containers?
If I would install MicroK8s, I still have to also manage the Ubuntu installation hosting it. Would be nice to have a distribution that only focuses on running docker containers and updates operating system and docker stuff together, so I know it always works fine together.
If you can run Docker, run Docker's Desktop Kubernetes Cluster.
You also can run minikube (on a top of docker, or hypervisor, or virtualbox)
kind - which is docker in docker k8s cluster.
This is a lab env for playing with Docker containers on Kubernetes without installing nothing: https://labs.play-with-k8s.com/
Minikube: https://github.com/kubernetes/minikube .
Docker Swarm: https://docs.docker.com/engine/swarm/ is an alternative to kubernetes with less features, but easy to setup. (comparison: https://medium.com/faun/kubernetes-vs-docker-swarm-whos-the-bigger-and-better-53bbe76b9d11)
Make your own cluster using VirtualBox: https://medium.com/#KevinHoffman/building-a-kubernetes-cluster-in-virtualbox-with-ubuntu-22cd338846dd
Local-machine Solutions
Community Supported Tools
Minikube is a method for creating a local, single-node Kubernetes cluster for development and testing. Setup is completely automated and doesn’t require a cloud provider account.
Kubeadm-dind is a multi-node (while minikube is single-node) Kubernetes cluster which only requires a docker daemon. It uses docker-in-docker technique to spawn the Kubernetes cluster.
Kubernetes IN Docker is a tool for running local Kubernetes clusters using Docker container “nodes”. It is primarily designed for testing Kubernetes 1.11+. You can use it to create multi-node or multi-control-plane Kubernetes clusters.
Ecosystem Tools
Docker Desktop is an easy-to-install application for your Mac or Windows environment that enables you to start coding and deploying in containers in minutes on a single-node Kubernetes cluster.
Minishift installs the community version of the Kubernetes enterprise platform OpenShift for local development & testing. It offers an all-in-one VM (minishift start) for Windows, macOS, and Linux. The container start is based on oc cluster up (Linux only). You can also install the included add-ons.
MicroK8s provides a single command installation of the latest Kubernetes release on a local machine for development and testing. Setup is quick, fast (~30 sec) and supports many plugins including Istio with a single command.
IBM Cloud Private-CE (Community Edition) can use VirtualBox on your machine to deploy Kubernetes to one or more VMs for development and test scenarios. Scales to full multi-node cluster.
IBM Cloud Private-CE (Community Edition) on Linux Containers is a Terraform/Packer/BASH based Infrastructure as Code (IaC) scripts to create a seven node (1 Boot, 1 Master, 1 Management, 1 Proxy and 3 Workers) LXD cluster on Linux Host.
Ubuntu on LXD supports a nine-instance deployment on localhost.
My very opionated answer: you should use k3s by Rancher Labs https://k3s.io/
I'm testing the side-by-side Windows/Linux container experimental feature in Docker for Windows and all is going well. I can create Linux containers while the system is set to use Windows containers. I see my ReplicaSets, Services, Deployments, etc in the Kubernetes dashboard and all status indicators are green. The issue, though, is that my external service endpoints don't seem to resolve to anything when Docker is set to Windows container mode. The interesting thing, however, is that if I create all of my Kubernetes objects in Linux mode and then switch to Windows mode, I can still access all services and the Linux containers behind them.
Most of my Googling took me to errors with services and Kubernetes but this doesn't seem to be suffering from any errors that I can report. Is there a configuration somewhere which must be set in order for this to work? Or is this just a hazard of running the experimental features?
Docker Desktop 2.0.0.3
Docker Engine 18.09.2
Kubernetes 1.10.11
just to confirm your thoughts about experimental features:
Experimental features are not appropriate for production environments or workloads. They are meant to be sandbox experiments for new ideas. Some experimental features may become incorporated into upcoming stable releases, but others may be modified or pulled from subsequent Edge releases, and never released on Stable.
Please consider additional steps to resolve this issue:
The Kubernetes client command, kubectl, is included and configured to connect to the local Kubernetes server. If you have kubectl already installed and pointing to some other environment, such as minikube or a GKE cluster, be sure to change context so that kubectl is pointing to docker-for-desktop
> kubectl config get-contexts
> kubectl config use-context docker-for-desktop
If you installed kubectl by another method, and experience conflicts, remove it.
To enable Kubernetes support and install a standalone instance of Kubernetes running as a Docker container, select Enable Kubernetes and click the Apply and restart button.
By default, Kubernetes containers are hidden from commands like docker service ls, because managing them manually is not supported. To make them visible, select Show system containers (advanced) and click Apply and restart. Most users do not need this option.
Please verify also System requirements.
Scenario:
I need to build a web-app, from which I can run/sop/delete/etc. containers in a cluster. So I installed Kubernetes and tested the API from the console. Everything seems working and looks fine.
Following the Docs, they write about Docker, but do I need it necessarily?
I mean I had to disable Hyper-V to make Minikube work, and after a reboot, Docker (which usually starts at startup) says that "something went wrong.. bla bla" .. but I can create deployments and proxys on Minikube.
This is somehow confusing.
Can someone explain this please for dummies?
Technically, you need a container runtime which respects CRI (Container Runtime Interface).
That is why you have CRI-O, which provides an integration path between OCI conformant runtimes and the kubelet.
See "CRI-O, the Project to Run Containers without Docker, Reaches 1.0" by Susan Hall.
The project “opens the door for plugging alternative container runtimes in the kubelet more easily, instead of relying on the default docker runtime.
Those new runtimes may include virtual machines-based ones, such as runv and Clear Containers, or standard Linux containers runtimes like rkt,” Red Hat senior engineer Antonio Murdaca wrote on the Project Atomic blog.
But in your case, your issue is to make Minikube work with HyperV: see "Minikube on Windows 10 with Hyper-V" from Jock Reed.
The trick is to create a new (External) Virtual network switch, named "Primary Virtual Switch", and to start Minikube with:
minikube start --vm-driver hyperv --hyperv-virtual-switch "Primary Virtual Switch"
If you're running minikube on OSX or Linux, you can configure Docker to use the minikube environment by running
eval $(minikube docker-env)
When you do this, you don't need a separate Docker desktop application. You're still technically using both Docker and Kubernetes, but you won't be using the setup with the "whale" icon on OSX.
Fundamentally Kubernetes takes responsibility for launching and managing Docker containers. (Or potentially other things, but almost always Docker containers.) It's a more complicated and more powerful tool along the same lines as Docker Compose and Docker Swarm. Minikube is very small Kubernetes cluster that runs inside a virtual machine; if you run kubectl get nodes you will see the single VM node, and that includes a copy of Docker.
As mentioned above, you need any runtime container. Kubernetes and docker are part of ecosystem. Both have different responsibilities, kubernetes handle cluster health and docker run application containers.
Most tutorials I've seen for developing with Kubernetes locally use Minikube. In the latest Edge release of Docker for Windows, you can also enable Kubernetes. I'm trying to understand the differences between the two and which I should use.
Minikube lets you choose the version of Kubernetes you want, can Docker for Windows do that? I don't see a way to configure it.
Minikube has CLI commands to enable the dashboard, heapster, ingress and other addons. I'm not sure why because my undertstanding is that these are simply executing kubectl apply -f http://....
With Minikube I can do a minikube ip to get the cluster IP address for ingress, how can I do this with Docker for Windows?
Is there anything else different that I should care about.
I feel like you largely understand the space, and mostly have answers to your questions already. You might find Docker for Mac vs. Docker Toolbox an informative read, even if it's about the Mac equivalent rather than Windows and about Docker packaged as a VM rather than Kubernetes specifically.
In fact you are stuck with the specific version of Kubernetes the Docker Edge desktop distribution publishes.
is answered in the question.
I believe NodePort-type Services are published on your host's IP address; there isn't an intermediate VM address like there is with Docker Toolbox.
Docker Toolbox and minikube always use a full-blown virtual machine with an off-the-shelf hypervisor. The Docker desktop application might use a lighter-weight virtualization engine if one is available.
Kubernetes can involve some significant background work. If you're using Kubernetes-in-Docker it's hard to "turn off" Kubernetes and still have Docker available; but if you have a separate minikube VM you can just stop it.
Here is a part from Docker documentation:
Kubernetes is only available in Docker for Windows 18.02 CE Edge.
Kubernetes support is not included in Docker for Windows 18.02 CE
Stable. To find out more about Stable and Edge channels and how to
switch between them, see General configuration.
Docker for Windows 18.02 CE Edge includes a standalone Kubernetes
server and client, as well as Docker CLI integration. The Kubernetes
server runs locally within your Docker instance, is not configurable,
and is a single-node cluster.
The Kubernetes server runs within a Docker container on your local
system, and is only for local testing. When Kubernetes support is
enabled, you can deploy your workloads, in parallel, on Kubernetes,
Swarm, and as standalone containers. Enabling or disabling the
Kubernetes server does not affect your other workloads.
See Docker for Windows > Getting started to enable Kubernetes and
begin testing the deployment of your workloads on Kubernetes.
If you have enough CPU and RAM resources, you can easily have both, minikube and docker-for-desktop on the same machine and switch between them by selecting the context, e.g.:
> kubectl config get-contexts
> kubectl config use-context docker-for-desktop
There is no place at the moment to choose the Kubernetes version for docker-for-desktop. It is preselected in the Docker distribution package.
Unfortunately, version of docker inside the minikube is a step behind compared to available on the docker website, and some features could be missing, but if you are interested in Kubernetes environment, it doesn't really matter in most cases.
Some of the features of Kubernetes rely on external resources and could be unavailable for you in case of local installation. For example, you need an ability to create Cloud Load Balancer to use some types of the Ingress or Service objects.
But other resources can be easily started inside the minikube, or docker-for-desktop using kubectl create/apply.
To expose your cluster resources externally, you can use Webhook Relay Ingress controller.
Here is a link to the installation manual.