I am using kubernete to manage docker cluster. Right now, I can set up POD autoscale using Horizontal Pod Scaler, that is fine.
And now I think the next step is to autoscale nodes. I think for HPA, the auto-created pod is only started in the already created nodes, but if all the available nodes are utilized and no available resource for any more pods, I think the next step is to automatically create node and have node join the k8s master.
I googled a lot and there are very limited resources to introduce this topic.
Can anyone please point me to any resource how to implement this requirement.
Thanks
One way to do using AWS and setting up your own Kubernetes cluster is by following these steps :
Create an Instance greater than t2.micro (will be master node).
Initialize the Kubernetes cluster using some tools like Kubeadm. After the initialisation would be completed you would get a join command, which needs to e run on all the nodes who want to join the cluster. (Here is the link)
Now create an Autoscaling Group on AWS with start/boot script containing that join command.
Now whenever the utilisation specified by you in autoscaling group is breached the scaling would happen and the node(s) would automatically join the Kubernetes cluster. This would allow the Kubernetes to schedule pods on the newly joined nodes based on the HPA.
(I would suggest to use Flannel as pod network as it automatically removes the node from Kubernetes cluster when it is not available)
kubernetes operations (kops) helps you create, destroy, upgrade and maintain production-grade, highly available, Kubernetes clusters from the command line.
Features:
Automates the provisioning of Kubernetes clusters in AWS and GCE
Deploys Highly Available (HA) Kubernetes Masters
Most of the managed kubernetes service providers provide auto scaling feature of the nodes
Elastic Kubernetes Service EKS- configure cluster auto scalar
Google Kubernetes Engine
GKE Auto Scalar
Auto scaling feature needs to be supported by the underlying cloud provider. Google cloud supports auto scaling during cluster creation or update by passing flags --enable-autoscaling --min-nodes and --max-nodes to the corresponding gcloud commands.
Examples:
gcloud container clusters create mytestcluster --zone=us-central1-b --enable-autoscaling --min-nodes=3 --max-nodes=10 --num-nodes=5
gcloud container clusters update mytestcluster --enable-autoscaling --min-nodes=1 --max-nodes=15
below link would be helpful
https://medium.com/kubecost/understanding-kubernetes-cluster-autoscaling-675099a1db92
Related
I have a project on Kubernetes and only 1 pod is running on each node and it has to be like that. How can I autoscale the nodes I want to build? So how can I create a new node when the load on the node increases. I am using AWS and Azure.
I am not sure why you want to run a pod per node. We have separate groups of applications and each group runs on certain node groups. We use cluster autoscaler to scale down/up nodes based on usage. We then use taints and tolerations on pods/nodes for each group of application. Cluster auto scaler will scale up nodes for the specific application group is pods are in pending status.
added below portion -
One useful article about scaling in kubernetes is here. You can read about Cluster Autoscaler (CA) as well.
I think you can try this with ClusterAutoscaler:
https://github.com/kubernetes/autoscaler/tree/master/cluster-autoscaler
When I use the command kubectl get nodes. I got list of nodes with ROLES . Are there any way I can find out which nodes are masters?
Use this command for this purpose.
kubectl get node --selector='node-role.kubernetes.io/master'
In EKS, according to the AWS Documentation:
The control plane runs in an account managed by AWS, and the Kubernetes API is exposed via the Amazon EKS endpoint associated with your cluster.
As mentioned in my comment above, you don't have access to the master node in an EKS cluster, as it is managed by AWS.
The idea behind it is to "make your life easier" and make you worry only about the loads that will run on the worker nodes.
There is also this documentation page, that may help in the understanding of EKS.
In ECS with Fargate, we can manage service isolation via security group. However that is no longer the case with EKS on Fargate.
Is there a way where pods on the same cluster can be isolated from each other like a Network Policy? I know this is possible with kubernetes but it needs to be implemented by the network plugin. Tried to install the network provider listed here without success as it needs daemonset (limitation of eks fargate: Cannot run Daemonsets, Privileged pods, or pods that use HostNetwork or HostPort.)
This is something we are tracking in this roadmap item. There isn't a viable workaround for now. As you pointed out when using EC2 we'd suggest to use the Calico network policy engine but with Fargate there is no DaemonSet support and it can't be used.
Given the SG associated to a pod is defined at the cluster level, one way to try to mitigate this would be to spread like-pods across different clusters where the pod SG is configured for that specific type of workload BUT this will mean more work and higher control plane costs.
I am new to the Kubernetes and cluster.
I would like to bring up an High Availability Master Only Kubernetes Cluster(Need Not to!).
I have the 2 Instances/Servers running Kubernetes daemon, and running different kind of pods on both the Nodes.
Now I would like to somehow create the cluster and if the one of the host(2) down, then all the pods from that host(2) should move to the another host(1).
once the host(2) comes up. the pods should float back.
Please let me know if there is any way i can achieve this?
Since your requirement is to have a 2 node master-only cluster and also have HA capabilities then unfortunately there is no straightforward way to achieve it.
Reason being that a 2 node master-only cluster deployed by kubeadm has only 2 etcd pods (one on each node). This gives you no fault tolerance. Meaning if one of the nodes goes down, etcd cluster would lose quorum and the remaining k8s master won't be able to operate.
Now, if you were ok with having an external etcd cluster where you can maintain an odd number of etcd members then yes, you can have a 2 node k8s cluster and still have HA capabilities.
It is possible that master node serves also as a worker node however it is not advisable on production environments, mainly for performance reasons.
By default, kubeadm configures master node so that no workload can be run on it and only regular nodes, added later would be able to handle it. But you can easily override this default behaviour.
In order to enable workload to be scheduled also on master node you need to remove from it the following taint, which is added by default:
kubectl taint nodes --all node-role.kubernetes.io/master-
To install and configure multi-master kubernetes cluster you can follow this tutorial. It describes scenario with 3 master nodes but you can easily customize it to your needs.
I have deployed an app using Kubernetes to a Google Cloud Container Engine Cluster.
I got into autoscaling, and I found the following options:
Kubernetes Horizontal Pod Autoscaling (HPA)
As explained here, Kubernetes offers the HPA on deployments. As per the docs:
Horizontal Pod Autoscaling automatically scales the number of pods in a replication controller, deployment or replica set based on observed CPU utilization
Google Cloud Container Cluster
Now I have a Google Cloud Container Cluster using 3 instances, with autoscaling enabled. As per the docs:
Cluster Autoscaler enables users to automatically resize clusters so that all scheduled pods have a place to run.
This means I have two places to define my autoscaling. Hence my questions:
Is a Pod the same as VM instance inside my cluster, or can multiple Pod's run inside a single VM instance?
Are these two parameters doing the same (aka creating/removing VM instances inside my cluster). If not, what is their behaviour compared to one another?
What happens if e.g. I have a number of pods between 3 and 10 and a cluster with number of instances between 1 and 3 and autoscaling kicks in. When and how would both scale?
Many thanks!
Is a Pod the same as VM instance inside my cluster, or can multiple
Pod's run inside a single VM instance?
Multiple Pods can run the same instance (called node in kuberenetes). You can define maximum resources to consume for a POD in the deployment yaml. See the docs. This is an important prerequisite for autoscaling.
Are these two parameters doing the same (aka creating/removing VM
instances inside my cluster). If not, what is their behaviour compared
to one another?
Kubernetes autoscaler will schedule additional PODs in your existing nodes. Google autoscaler will add worker nodes (new instances) to your cluster. Google autoscaler looks at queued up PODs that cannot be scheduled because there is no space in your cluster and when it finds those will add nodes.
What happens if e.g. I have a number of pods between 3 and 10 and a
cluster with number of instances between 1 and 3 and autoscaling kicks
in. When and how would both scale?
By the maximum resource usage you define for your pods google autoscaler will estimate how many new nodes are required to run all queued up, scheduled pods.
Also read this article.