I managed to install a 3-node cluster on VMs within the same network.
But is there a way to install a multi-node K8S cluster on VMs with different IP ranges? (VMs which are not located in the same network)
The reason for this question is the scenario that I have in mind:
I need to deploy a micro-service application (written in Java) with K8S. I made docker images from each service in my application and its working locally.
I plan to have each service to be run in a separate physical location (within different networks)
For this I need a multi-node cluster, but each node will get different IP range. Is this possible?
if there is a connectivity among the three nodes then i dont see any reason why you cant setup multi node cluster.
note that kubernetes needs the machines to be closer. because lot of calls happen between api server, kubelet, kube-proxy. it would hit cluster and application performance.
Related
Good afternoon!
In my study of Kubernetes, I got to the practice of deploying Kuber on the server. There are different deployment scenarios. I chose kubespray. Can you tell me if you can somehow deploy kuber on a host? Or is it necessary to create virtual machines, set up a network between them and only then deploy the cluster?
Node: A node may be a virtual or physical machine, depending on the cluster. Each node is managed by the control plane and contains the services necessary to run Pods.
You can deploy single Node Kubernetes
For local (development, test etc) purposes:
minikube
kind
...
For production:
k3s
k0s
...
And, of course, you can create separate nodes under one "machine." And use them as worker nodes, but the above solutions are simpler.
I'm new to kubernetes and trying to explore the new things in it. So, my question is
Suppose I have existing kubernetes cluster with 1 master node and 1 worker node. Consider this setup is on AWS, now I have 1 more VM instance available on Oracle Cloud Platform and I want to configure that VM as worker node and attach that worker node to existing cluster.
So, is it possible to do so? Can anybody have any suggestions regarding this.
I would instead divide your clusters up based on region (unless you have a good VPN between your oracle and AWS infrastructure)
You can then run applications across clusters. If you absolutely must have one cluster that is geographically separated, I would create a master (etcd host) in each region that you have a worker node in.
Worker Node and Master Nodes communication is very critical for Kubernetes cluster. Adding nodes from on-prem to a cloud provider or from different cloud provider will make lots of issues from network perspective.
As VPN connection between AWS and Oracle Cloud needed and every time worker node has to cross ocean (probably) to reach master node.
EDIT: From Kubernetes Doc, Clusters cannot span clouds or regions (this functionality will require full federation support).
https://kubernetes.io/docs/setup/best-practices/multiple-zones/
I am new to the Kubernetes, and I'm trying to understand that how can I apply it for my use-case scenario.
I managed to install a 3-node cluster on VMs within the same network. Searching about K8S's concepts and reading related articles, still I couldn't find answer for my below question. Please let me know if you have knowledge on this:
I've noticed that internal DNS service of K8S applies on the pods and this way services can find each other with hostnames instead of IPs.
Is this applicable for communication between pods of different nodes or this is only within the services inside a single node? (In other words, do we have a dns service on the node level in the K8S, or its only about pods?)
The reason for this question is the scenario that I have in mind:
I need to deploy a micro-service application (written in Java) with K8S. I made docker images from each service in my application and its working locally. Currently, these services are connected via pre-defined IP addresses.
Is there a way to run each of these services within a separate K8S node and use from its DNS service to connect the nodes without pre-defining IPs?
A service serves as an internal endpoint and (depending on the configuration) load balancer to one or several pods behind it. All communication typically is done between services, not between pods. Pods run on nodes, services don't really run anything, they are just routing traffic to the appropriate pods.
A service is a cluster-wide configuration that does not depend on a node, thus you can use a service name in the whole cluster, completely independent from where a pod is located.
So yes, your use case of running pods on different nodes and communicate between service names is a typical setup.
I have played around a little bit with docker and kubernetes. Need some advice here on - Is it a good idea to have one POD on a VM with all these deployed in multiple (hybrid) containers?
This is our POC plan:
Customers to access (nginx reverse proxy) with a public API endpoint. eg., abc.xyz.com or def.xyz.com
List of containers that we need
Identity server Connected to SQL server
Our API server with Hangfire. Connected to SQL server
The API server that connects to Redis Server
The Redis in turn has 3 agents with Hangfire load-balanced (future scalable)
Setup 1 or 2 VMs?
Combination of Windows and Linux Containers, is that advisable?
How many Pods per VM? How many containers per Pod?
Should we attach volumes for DB?
Thank you for your help
Cluster size can be different depending on the Kubernetes platform you want to use. For managed solutions like GKE/EKS/AKS you don't need to create a master node but you have less control over our cluster and you can't use latest Kubernetes version.
It is safer to have at least 2 worker nodes. (More is better). In case of node failure, pods will be rescheduled on another healthy node.
I'd say linux containers are more lightweight and have less overhead, but it's up to you to decide what to use.
Number of pods per VM is defined during scheduling process by the kube-scheduler and depends on the pods' requested resources and amount of resources available on cluster nodes.
All data inside running containers in a Pod are lost after pod restart/deletion. You can import/restore DB content during pod startup using Init Containers(or DB replication) or configure volumes to save data between pod restarts.
You can easily decide which container you need to put in the same Pod if you look at your application set from the perspective of scaling, updating and availability.
If you can benefit from scaling, updating application parts independently and having several replicas of some crucial parts of your application, it's better to put them in the separate Deployments. If it's required for the application parts to run always on the same node and if it's fine to restart them all at once, you can put them in one Pod.
the kubernetes 1.2 support muti-node acrossing multiple service providers , now the master node running in my laptop , I want to add two work node respectively in amazon and vagrant . how to achieve it?
the kubernetes 1.2 support muti-node acrossing multiple service providers
Where did you see this? It isn't actually true. In 1.2 we added support for nodes across multiple availability zones within the same region on the same service provider (e.g. us-central1-a and us-central1-b in the us-central1 region in GCP). But there is no support for running nodes across regions in the same service provider much less spanning a cluster across service providers.
now the master node running in my laptop , I want to add two work node respectively in amazon and vagrant
The worker nodes must be able to connect directly to the master node. I wouldn't suggest exposing your laptop to the internet directly so that it can be reached from an Amazon data center, but would instead advise you to run the master node in the cloud.
Also note that if you are running nodes in the same cluster across multiple environments (AWS, GCP, Vagrant, bare metal, etc) then you are going to have a difficult time getting networking configured properly so that all pods can reach each other.