Let’s say I have this release called mongodb in mongo Kubernetes namespace: For this release (mongodb), if I want to find out which repository (URL) the mongodb-sharded-5.0.17 chart came from then one way is to figure out the environment from which the helm chart was installed and run helm search repo there: But in some […]
Consider this post more of a summary or a cheat sheet of the important parts mentioned in the documentation about DNS records automatically created for Services and Pods in your K8S cluster’s DNS Server. Kubelet configures each Pod’s DNS (/etc/resolv.conf) so that the running containers can make requests to/perform DNS lookups for Services and other […]
In this post I will go through some concepts and/or actions you should know about when you have to send emails from custom domains like [email protected]. This is a common requirement when you want to send emails to your users for different kinds of notifications (welcome mails, payment mails, marketing mails, etc.). I will not […]
If you’re running a StatefulSet application/workload in Kubernetes like a database (Postgres, Mongo, ElasticSearch, etc.), at some point your disk storage will get full and you will have to increase the size of the StatefulSet’s persistent volumes. Let’s go through the steps to do this. First of all, if you are provisioning persistent volumes for […]
Let’s cover everything you need to know about resizing Kubernetes volumes to expand their size (upsizing). Downsizing is not possible. We will talk keeping persistent volumes in mind but most of what we discuss should also be applicable to Generic ephemeral volumes. Also when we say “resizing volumes”, we refer to resizing the actual storage […]
In Kubernetes, if you store some data (create a file, write to it, modify a file, etc.) in a container running inside your pod, the changes won’t persist once the container stops running (crashes, stops normally or restarts). For better data persistence, Kubernetes provides the following options: Now when specifically working with Persistent Volumes, they […]
The short answer is IT DEPENDS. Let’s say you have a PVC called myclaim: You can go ahead and create multiple pods whose spec try to use this PVC, K8S will allow us to schedule all these pods without any validation error: But whether multiple pods are able to mount the same volume that the […]
The short answer is NO. As mentioned in the documentation, PersistentVolumeClaims (PVC) and PersistentVolumes (PV) in K8S have a one-to-one relationship: A PVC to PV binding is a one-to-one mapping, using a ClaimRef which is a bi-directional binding between the PersistentVolume and the PersistentVolumeClaim. When a PVC is using a PV, its spec.volumeName points to […]
Sometimes we want to cleanup a bunch of pods that are failing to get scheduled or failing to execute after getting scheduled. Removal and cleanup of pods failing to execute can even help scale down your cluster workers and hence reduce costs. When I say failing pods, it means pods with statuses (that you see […]
The short answer to this question is that you cannot. For a slightly descriptive answer, keep reading. Let’s say you try deleting a PersistentVolume (kubectl delete pv [pv_name]) that is bound to a PersistentVolumeClaim, it will get stuck in Terminating state. This is because the PV has a Finalizer (kubernetes.io/pv-protection) that prevents it from accidentally […]