I am trying to understand the relationship between Kubernetes and OpenStack. I am confused around the topic of deploying Kubernetes on OpenStack and doing my research I found there are too many tutorials. My understanding of the sequence is:
Start several nova instances on OpenStack.
Install Kubernetes master on one instance and install Kubernetes node on other instances.
Submit YAML file using kubectl and Kubernetes will create and deploy my application.
As for Kubernetes's self-healing capacity, can Kubernetes restart some of the failed nova instances? Which component in Kubernetes is responsible for restart/reboot/delete/re-provision nova instances? Is it Kubernetes master? If so, what will happen if the Kubernetes master is down and cannot be recovered?
1, 2 and 3 are correct.
Self-healing
You can deploy in master HA configuration. The recommended way is either 3 or 5 master with a quorum of (n + 1)/ 2
Can Kubernetes reprovision/restart some the failed nova instances?
Not really. That's after nova to manage all the server services. Kubernetes has an OpenStack module that allows it to interact with OpenStack components like create external load balancer and creates volumes that can be used with your workloads/pods/containers.
You can either use kubeadm or kubespray to bootstrap a cluster.
Hope it helps.
If you want to deploy Kubernetes on top of Openstack I would recommend that you look into Openstack Magnum. This is the most common use case for Openstack and Kubernates.
There is also the possibility of running the Openstack Control Plane under Kubernetes, which would allow you to better scale and auto-heal Openstack services. This is primarily for the Control Plane (e.g. nova-api), and as far as I know there is no way of running nova-computes under Kubernetes.
I found a good blog post here that describes some of the benefits from such an approach.
Yes, you're spot on with your observations in the case of running Kubernetes on top of OpenStack and the other answers here give you further pointers already. I just wanted to point out, in addition, that the other way round is also an option, that is, running OpenStack on top of Kubernetes, for example using OpenStack-Helm.
Related
I am new to Spinnaker. I want to setup Spinnaker in my lab to test some pipeline deployments to K8s. I read through a lot of videos and websites teaching how to setup Spinnaker using Helm, Hal, Operator, etc. The steps and requirements are quite complex and I am struggling which method I should take
For my lab environment, I have 3 VM running in CentOS (bare metal) and built a Kubernetes cluster on them (1 master and 2 slave nodes). And now I want to setup Spinnaker to test microservice deployment on this k8s cluster in an easy and quick way
Some of my doubts
If I chose Spinnaker on Kubernetes cluster, do I need to setup another new k8s cluster? Or I can use the same cluster that already has several microservices running on it?
If I chose Spinnaker on VM, guess I need to spin up a new Ubuntu machine instead of setting in on my existing CentOS machine?
Any suggestion is welcome. Thanks!
I know many services provided a managed control plane. GKE, Digital Ocean. I want a Kubernetes cluster using those service as they provide reliablity. But I want to expand my kubernetes cluster using a number of physical machines, old machines, raspberry pis etc that I have in my local office.
Is it possible? If so, how can I do that?
I found two questions in stackoverflow related to this, but both go with unsatisfactory answers
Add external node to GCP Kubernetes Cluster
Here the answer seems to be using kubeadm init - which really is not about adding a worker node, but doing making the control plane HA.
GKE with Aws worker nodes
Says it is possible, but does not mention how to add external worker nodes.
I am trying to create Kubernetes cluster having 1 master and 2 worker nodes by using the tool kubeadm in my on-premise machines. I am following the Kubernetes official documentation for forming the cluster from the following url:
https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/high-availability/
After installing all the runtime and completing before begin pre-requistics steps, I found in the document as the first step of forming the cluster is Create load balancer for kube-apiserver.
My Doubt
When I created the single master 3 worker nodes cluster using kubespray tool, I did not created any separate load balancer for that. So here when I am following the kubeadm tool, Do I need to create the load balancer actually for forming ?
Why are both tools showing different way, Since I did not created load balancer by using kubespray tool. Now I am trying to create cluster with kubeadm tool.
Speaking of load balancers creation during Kubernetes deployment using Kubeadm it depends on your setup. It is not mandatory to setup load balancer. Your cluster will still work, but without load balancing, it's going to be hard to qualify this cluster as HA.
In a single master setup as it is in your case, the master node manages the etcd database, API server, controller manager and scheduler, along with the worker nodes. However, if that single master node fails, all the worker node fail as well and entire cluster will be lost.
Learn more here: kubernetes-ha-kubeadm.
Kubeadm covers the needs of a life-cycle management for Kubernetes clusters, including self-hosted layouts, dynamic discovery services, etc. Kubespray is more about generic configuration, initial clustering, and bootstrapping.
Kubespray is a good choice when you either are familiar with Ansible or seek a possibility to switch between multiple platforms. If your priority is tight integration with unique features offered by the supported clouds, and you plan to stick with your provider, kops may be a better option.
Deploying a loadbalancer is up to a user and is not covered by ansible roles in Kubespray. By default, it only configures a non-HA endpoint, which points to the access_ip or IP address of the first server node in the kube-master group. It can also configure clients to use endpoints for a given loadbalancer type. More information you can find here: kubespray-lb.
Here you have comparision of Kubernetes deployment tools: Kubernetes Deployment Tools.
I am trying to install kubernetes on Self-hosted production environment running on Ubuntu 16.04. I am not able to find any helpful guide to setup production grade kubernetes master and connect worked nodes to it.
any help is much appreciated.
you can use the kubespray to self Host production environment.
https://github.com/kubernetes-incubator/kubespray
Depends on what you understand by saying "self-host". The most people think it's about deploying kubernetes in the own environment.
If you want to compare different approaches to deploy k8s in a custom environment, refer to this article which covers a bunch of options suitable for that.
If you are interested in how to set up an HA Kubernetes cluster using kubeadm, refer to this article.
However, in kubernetes, there is a different definition of "self-hosted". It means running kubernetes itself as a workload in kubernetes. If you are interested in a real self-hosted approach (on a custom environment), refer to this article
Hope this helps
You can use typhoon which can be used to provision an HA kubernetes cluster.
Here is a sample configuration which I used to bring up my own home cluster.
A few advantages of typhoon are that you have the option of choosing your choice of a cloud provider for provisioning your infrastructure, which is done using terraform and the fact that it gives you upstream k8s is a big plus too.
Internally, it uses bootkube to bring up the temporary control plane, which would consist of
api-server
controller-manager
scheduler
and then when we have the temporary control plane object, we inject the objects to the API server to have our k8s cluster.
Have a look at this kubecon talk given by CoreOS which explains how this is working.
I'm trying to use the Kubernetes to deploy Docker Container and I found this tutorial.
So according to this tutorial, what is the prerequisites?
They said that "services that are typically on a separate Kubernetes master system and two or more Kubernetes node systems are all running on a single system."
But I don't understand how we run both master and nodes on a single system (for example I have one instance EC2 with IP address 52.192.x.x)
That is a guide about running Kubernetes specifically on RedHat Atomic nodes. There are lots of guides about running Kubernetes on other types of nodes; see the Creating a Kubernetes Cluster page on docs.k8s.io.
One of the guides on the Kubernetes site shows how to run a local docker-based cluster, which should also work for you on a single node in the cloud.