Skip to main content

Kubernetes–What is the difference between resource requests and limits?

In Kubernetes it is a best practice to configure resource limits for your containers. VSCode will even warn you if it couldn’t detect resource limits in your manifest files:

Setting resource limits prevents a container consuming too much resources and impacting other workloads. By setting limits, pods will be terminated by Kubernetes when their limits are exceeded. This helps in keeping the cluster healthy and stable.

The most common resources to specify are CPU and memory, but others exists.

Here is a short example on how to configure this at the container level:

In the example above, the CPU usage is limited to 250m or  250 milliCPU (1/4th of a vCPU/Core) and memory usage is limited to 512Mi or 512MiB.

Next to resource limits, it is also possible to configure resource requests. Setting a resource request indicates the amount of that resource that you expect the container will use. Kubernetes will use this information when determining which node to schedule the pod on.

A node will be ineligible to host a new container if the sum of the workload requests, including the new container’s request, exceeds the available capacity. This remains the case even if the real-time memory use is actually very low.  This is the reason why it is best to keep the requests values as low as possible and setting the limits as high as possible(without bringing other workloads into trouble). Using a low resource request value gives your pods the best chance of getting scheduled to a node.

Limits are also configured in the resource section of your manifest file:

More information: https://kubernetes.io/docs/concepts/configuration/manage-resources-containers/

Labels:

Popular posts from this blog

.NET 8–Keyed/Named Services

A feature that a lot of IoC container libraries support but that was missing in the default DI container provided by Microsoft is the support for Keyed or Named Services. This feature allows you to register the same type multiple times using different names, allowing you to resolve a specific instance based on the circumstances. Although there is some controversy if supporting this feature is a good idea or not, it certainly can be handy. To support this feature a new interface IKeyedServiceProvider got introduced in .NET 8 providing 2 new methods on our ServiceProvider instance: object? GetKeyedService(Type serviceType, object? serviceKey); object GetRequiredKeyedService(Type serviceType, object? serviceKey); To use it, we need to register our service using one of the new extension methods: Resolving the service can be done either through the FromKeyedServices attribute: or by injecting the IKeyedServiceProvider interface and calling the GetRequiredKeyedServic...
Read more

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