Skip to main content

Kubernetes–Schedule a pod on a Linux node–Part 2

Yesterday I blogged about the usage of the “kubernetes.io/os” nodeselector to schedule a pod specifically on a windows or linux node pool.

Today I want to share another way through the usage of taints and tolerations.

This Kubernetes feature allows users to mark a node (taint the node) so that no pods can be scheduled to it, unless a pod has a toleration that indicates it will accept this taint. Using this Kubernetes feature we can create nodes that are reserved (dedicated) for specific pods.  Using this, we can pick one OS and taint all the nodes with this OS, so that any pods that do not specify toleration will use the non-tainted nodes. This Taint effectively allows us to specify a default OS for the cluster, and if you want to use the other OS, you need to state this explicitly.

To enable this, we first need to taint our Windows nodes. We would run this command for each Windows node:

kubectl taint nodes <nodeName> OS=Windows:NoSchedule

After this is applied it will prevent any pods that do not tolerate that condition from running on that node.

Now we need to update our pod spec for our Windows app to tolerate this.

If no toleration is specified, the pod will default to running on the Linux nodes.

More information: https://docs.microsoft.com/en-us/azure-stack/aks-hci/adapt-apps-mixed-os-clusters

Labels:

Popular posts from this blog

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.
Read more

Kubernetes–Limit your environmental impact

Reducing the carbon footprint and CO2 emission of our (cloud) workloads, is a responsibility of all of us. If you are running a Kubernetes cluster, have a look at Kube-Green . kube-green is a simple Kubernetes operator that automatically shuts down (some of) your pods when you don't need them. A single pod produces about 11 Kg CO2eq per year( here the calculation). Reason enough to give it a try! Installing kube-green in your cluster The easiest way to install the operator in your cluster is through kubectl. We first need to install a cert-manager: kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.14.5/cert-manager.yaml Remark: Wait a minute before you continue as it can take some time before the cert-manager is up & running inside your cluster. Now we can install the kube-green operator: kubectl apply -f https://github.com/kube-green/kube-green/releases/latest/download/kube-green.yaml Now in the namespace where we want t...
Read more

DevToys–A swiss army knife for developers

As a developer there are a lot of small tasks you need to do as part of your coding, debugging and testing activities.  DevToys is an offline windows app that tries to help you with these tasks. Instead of using different websites you get a fully offline experience offering help for a large list of tasks. Many tools are available. Here is the current list: Converters JSON <> YAML Timestamp Number Base Cron Parser Encoders / Decoders HTML URL Base64 Text & Image GZip JWT Decoder Formatters JSON SQL XML Generators Hash (MD5, SHA1, SHA256, SHA512) UUID 1 and 4 Lorem Ipsum Checksum Text Escape / Unescape Inspector & Case Converter Regex Tester Text Comparer XML Validator Markdown Preview Graphic Col...
Read more