I tried to find the answer in previous post, but i did not find it !
My question seems dumb, i'm just trying to figure it out :)
I'm new to docker and kubernetes, i'm trying to understand the architecture of kubernetes cluster, nodes, and pods.
I'm using two machines with docker installed, each machine have two containers running, i want to install MicroK8s to start playing with kubernetes, my questions are :
As below image > Can I install it on separate machine and connect it to my docker host machines so it will manage my containers their with support of some sort of (agent/ maybe services) ?, Or kubernetes/MicroK8s must be installed on the machine that will host the containers ?
Can i add my running docker containers directly to a pod ? or i must re-create them ?
Many thanks
You can play with any VM software(cpu virtualization required).
You can set up 3 VMs(master, node1,node2). You have to install kubernetes in each VM. When you connect them thru calico they communicate each other. When you make pods with app or db , you can loadbalance to node1 and node2 or more from master. Then you can create a service to export route to the pods. Or If you want to run everything in one big server, you can. Horizontal scaling or vertical scaling is your choice.
you cant mount a running docker container to the pod but you can load a docker image from any registry.
Related
I have several Windows servers available and would like to setup a Kubernetes cluster on them.
Is there some tool or a step by step instruction how to do so?
What I tried so far is to install DockerDesktop and enable its Kubernetes feature.
That gives me a single node Cluster. However, adding additional nodes to that Docker-Kubernetes Cluster (from different Windows hosts) does not seem to be possible:
Docker desktop kubernetes add node
Should I first create a Docker Swarm and could then run Kubernetes on that Swarm? Or are there other strategies?
I guess that I need to open some ports in the Windows Firewall Settings of the hosts? And map those ports to some Docker containers in which Kubernetes is will be installed? What ports?
Is there some program that I could install on each Windows host and that would help me with setting up a network with multiple hosts and connecting the Kubernetes nodes running inside Docker containers? Like a "kubeadm for Windows"?
Would be great if you could give me some hint on the right direction.
Edit:
Related info about installing kubeadm inside Docker container:
https://github.com/kubernetes/kubernetes/issues/35712
https://github.com/kubernetes/kubeadm/issues/17
Related question about Minikube:
Adding nodes to a Windows Minikube Kubernetes Installation - How?
Info on kind (kubernetes in docker) multi-node cluster:
https://dotnetninja.net/2021/03/running-a-multi-node-kubernetes-cluster-on-windows-with-kind/
(Creates multi-node kubernetes cluster on single windows host)
Also see:
https://github.com/kubernetes-sigs/kind/issues/2652
https://hub.docker.com/r/kindest/node
You can always refer to the official kubernetes documentation which is the right source for the information.
This is the correct way to manage this question.
Based on Adding Windows nodes, you need to have two prerequisites:
Obtain a Windows Server 2019 license (or higher) in order to configure the Windows node that hosts Windows containers. If you are
using VXLAN/Overlay networking you must have also have KB4489899
installed.
A Linux-based Kubernetes kubeadm cluster in which you have access to the control plane (see Creating a single control-plane cluster with kubeadm).
Second point is especially important since all control plane components are supposed to be run on linux systems (I guess you can run a Linux VM on one of the servers to host a control plane components on it, but networking will be much more complicated).
And once you have a proper running control plane, there's a kubeadm for windows to proper join Windows nodes to the kubernetes cluster. As well as a documentation on how to upgrade windows nodes.
For firewall and which ports should be open check ports and protocols.
For worker node (which will be windows nodes):
Protocol Direction Port Range Purpose Used By
TCP Inbound 10250 Kubelet API Self, Control plane
TCP Inbound 30000-32767 NodePort Services All
Another option can be running windows nodes in cloud managed kuberneres, for example GKE with windows node pool (yes, I understand that it's not your use-case, but for further reference).
I have two physical machines both running in the same network, and I made one of them a manager and the other one worker. The nodes join correctly and I was able to view them by running docker node ls.
In the docker yml file, I have 4 applications in total which two on them running on the manager node and others running on the worker node.
My issue is that the applications in the manager node cannot reach the applications in the worker node via the overlay network.
More information:
The manager node is running Ubuntu 18.04 LTS, and the worker node is running on a Mac mini(macOS 10.14.1). The architecture looks like the below:
I suspect this is a Mac issue. Any ideas?
I have been trying to work around similar issues. The root cause is because Docker Desktop for MacOS is not a "true docker" and it does not forward network requests from/to other hosts properly. Details are here: https://docs.docker.com/docker-for-mac/docker-toolbox/
The work around is to use Virtual Machines in MacOS (e.g., VirtualBox) by docker-machine command lines. Details are introduced in How to connect to a docker container from outside the host (same network) [OSX 10.11]
I have tried the VirtualBox path, adding a third Network Adapter with bridged mode, and I can finally ping 3 nodes from the container.
I have a simple one master (Ubuntu 1604), one worker (Windows Server 1803) Kubernetes cluster running in AWS. I am using Flannel for networking.
I have been able to deploy windows containers using kubectl from the master without issue. Deploying multiple pods shows they are able to talk to each other. But I am not able to ping or curl the pods from even the Kubernetes windows node host, or from the open internet. Also, the pods are not able to communicate with the outside internet either. (Can't curl external DNS names or even IP addresses.)
Side note: Deploying the same image directly with Docker on the Windows node is able to connect to the internet and be accessed over the internet.
I used the following setup from Microsoft, which uses kubeadm, flannel and scripts from Microsoft SDN repo.
https://onedrive.live.com/view.aspx?resid=E2B6765015E5FA01!339&ithint=file%2cdocx&app=Word&authkey=!AGvs_s_hWs7xHGs
It is my understanding that on Windows the host network interface is not connected to the Kubernetes network interface by default, but the Docker network uses the default interface. Which might be why docker deployments can be accessed but Kubernetes deployments cannot.
However, I haven't found info on connecting these networks when using Flannel for pod communication on Windows.
I can add any logs or config info that anyone thinks is useful.
Any thoughts? Thanks for your help!
More Details:
I am looking into this: https://unofficial-kubernetes.readthedocs.io/en/latest/getting-started-guides/windows/ which describes connecting network interfaces between the Windows default and Kubernetes, but does not seem to rely on the same Flannel Host-GW model I used to set this up.
I have installed CoreOS on a laptop to use it as a Docker host. I really like Kitematic on my mac to create and manager containers. I dont see an option to connect to the remote docker on CoreOS using Kitematic. Are there other tools I can use to connect to a remote docker host and use GUI rather than command line to manager it.
I also like Kitematic a lot! As an alternative in CoreOS, you can try docker-ui, and it's evolution portainer.
They are both docker containers that can help you find / run docker images and inspect docker volumes / network / container stats.
You can also launch new containers directly through the web UI. More information on this good review of the portainer's possibilities
Rancher UI from Rancher Labs maybe also be worth looking at. It is more designed as a docker orchestration tool (when you operate a docker swarm cluster for instance).
Here's my setup, this output was taken from docker-machine ls. Using docker machine to provision the swarm.
NAME ACTIVE DRIVER STATE URL SWARM DOCKER ERRORS
cluster-master * (swarm) digitalocean Running tcp://REDACTED:2376 cluster-master (master) v1.11.1
kv-store - digitalocean Running tcp://REDACTED:2376 v1.11.1
node-1 - digitalocean Running tcp://REDACTED:2376 cluster-master v1.11.1
node-2 - digitalocean Running tcp://REDACTED:2376 cluster-master v1.11.1
Right now I'm searching for a way to setup my CI/CD workflow. Here is my initial idea:
Create an automatic build on docker hub (bitbucket)
Once changes are pushed, trigger build on docker hub
Testing will be done on docker hub (npm test)
Create a webhook on docker hub once build is success.
The webhook will point to my own application that will then push the changes to the swarm
Questions:
Is it okay to run your testing on docker hub or should I rely on another service?
If I will rely on another service what is your recommended service?
My main problem is pushing the changes to the docker swarm. Should I setup my docker-swarm on a remote machine and host the application there?
The first part of the process all looks fine. Where it gets complicated is managing the deployed production containers.
Is it okay to run your testing on docker hub or should I rely on
another service?
Yes it should be fine to run tests on docker hub assuming you don't need further integration tests.
I need to integrate my containers with amazon services and have a fairly non-standard deployment so this part of the testing has to be done on an amazon instance.
My main problem is pushing the changes to the docker swarm. Should I setup my docker-swarm on a remote machine and host the application there?
If you're just using one machine you don't need the added overhead of using swarm. If you're planning to scale to a larger multi-node deployment, yes deploy to a remote machine because you'll discover sooner the gotchas around using swarm.
You need to think about how you retire old versions and bring in the latest version of your containers to the swarm which is often called scheduling.
One simple approach that can be used is:
Remove traffic from old running container
Stop old running container
Pull latest container
Start latest container
Rinse and repeat for all running containers.
This is done in docker swarm by declaring a service. Then updating the image which can be watched as a task. For more information on the detail of this process see Apply rolling update to swarm and for how to do this in Amazon updating docker containers in ecs