The basic idea behind Kubernetes (aka K8s) is that you declare/describe the desired state of your application infrastructure via a manifest file, for example: “Run 3 nodes in 1 cluster, each containing my application”. Kubernetes will spin it all up, observe the actual state with the desired state continuously and adjust/reconcile if necessary. For example, […]
Networking using Services Each Pod has its own IP address. Containers within a Pod can communicate with each other via their ports over localhost. But how does one Pod communicate with another? We cannot rely on a Pod’s IP address because they get dynamically created or destroyed along with the Pod. The solution: We use […]
Here is the assumed prerequisite: Your application runs in Containers. You use Kubernetes for orchestration and know that those Containers are put inside Pods. What your application needs is a way to store data permanently. Can you use the layered-filesystem of your Containers? No, because that gets destroyed as soon as the container is gone. […]
The word deployment is a bit overloaded with different meanings: A deployment is about getting your application code running on servers. In Kubernetes a Deployment is also the name of a resource or API object that deals with deployments. You will end up defining YAML-files that create these Deployment resources. k8syaml.com can assist you to […]
A classic example of multi container pods is when you have your Main app Container separated from a Container that has helper code. That way you separate responsibility and the Helper Container can be reused in other pods. Multi Container patterns Depending on the role of each container in a Pod, best practices (or design […]
What is Helm and why would you need it? What problem does it solve? How you deploy to Kubernetes without Helm Maybe so far you have deployed your applications to Kubernetes by doing these steps: Create Docker Images of your application code Create YAML files specifying Kubernetes objects that your application requires (Deployment, Services, Secret, […]