Kubernetes Objects Required For A Typical Web Application: Part II
By Sudheer S
In the Kubernetes Objects Required For A Typical Web Application post we talked about few Kubernetes objects that a web application developer should get accustomed to. In this post, we will extend the series and talk about more objects that can help web developers scale their applications.
As we delve deeper into Kubernetes topics, the demarcation of roles and skill sets start to reveal. In larger organizations, a dedicated team of infrastructure engineers design and make choices of network topology, IAC tooling and orchestration of the Kubernetes clusters and CI/CD pipelines. Typically, such DevOps engineers manage scaling and storage by installing the required controllers and CSI drivers. Application developers whose applications are deployed on the cluster maybe able to tune certain parameters of certain objects to manage the scaling needs of their applications. Depending on the situation, the developers maybe able to request and use storage volumes with certain restrictions. Regardless of the organization’s team structure, you should be able to learn about these Kubernetes concepts and objects and play with them locally on your laptop using Minikube.
Horizontal Pod Autoscaler abbreviated as HPA
The Horizontal Pod Autoscaler (HPA) is a powerful feature in Kubernetes that automatically scales the number of pods up or down based on resource utilization. When a pod’s memory or CPU consumption breaches the limits, more pods can be added to cater to the demand. This is especially useful for web applications that experience spikes in traffic, which can increase CPU and memory consumption. By deploying the HPA, Kubernetes can handle autoscaling for you, ensuring that your application can handle changes in traffic volume without manual intervention. However, to get the most out of HPA, it’s essential to define the requests and limits of your pods using the resources section. By doing so, you can better understand your application’s resource utilization and ensure that it is optimized for efficient scaling.
Pod Disruption Budget abbreviated as PDB
If you have several identical copies of a pod in your Kubernetes cluster. Sometimes you might need to perform maintenance or upgrades on the nodes where these pods are running. If too many pods are down at the same time, it could cause issues for your application’s availability.
This is where PDB comes in handy! It allows you to control the number of replicated pods that can be taken down at the same time. By setting a PDB, you can ensure that a minimum number of pods remain running at all times, even during maintenance. This helps to avoid downtime and maintain the reliability of your application.
In short, PDB is a useful tool for ensuring that your application remains available during maintenance or upgrades by controlling the number of pods that can go down simultaneously.
Job
If you have a task that needs to be executed just once, like a batch job, a data migration job, or a backup job, you can use a Job object to run this one-off task.
A Job object instructs Kubernetes to spin up a dedicated pod to execute the task. Once the pod completes the task successfully, Kubernetes automatically terminates the pod, and your job is done! You don’t have to worry about manually starting or stopping the pod.
Jobs are useful for running tasks that need to be done just once, like data processing, backups, or batch jobs. They ensure that the task is executed reliably and completely, without requiring manual intervention.
In short, Jobs are a convenient way to run one-off tasks in Kubernetes. They provide a simple and reliable way to execute tasks and ensure that they are completed successfully.
CronJob
Have you ever used cron to schedule commands or jobs in your web application? You can do the same thing in
Kubernetes using CronJobs!
A CronJob is a Kubernetes object that allows you to schedule a Job to run on a repeating schedule. You can use the same syntax you’re already familiar with from cron, which makes it really easy to set up.
For example, you might want to run a backup of your database every night at midnight. You can create a CronJob in Kubernetes that runs a backup job every day at 02 AM. Once you create the CronJob, Kubernetes takes care of scheduling the backup jobs automatically, so you don’t have to worry about it.
CronJobs are super useful for automating repetitive tasks in your Kubernetes cluster, and they make it really easy to schedule jobs on a regular basis.
Persistent Volume abbreviated as PV
You have a web application that needs some storage to store data like images, videos, or documents. In Kubernetes, you can use a Persistent Volume (PV) to provide this storage for your application.
A Persistent Volume is a piece of storage that is provided by the Kubernetes administrator. The storage can be a disk on a physical machine or a networked storage device. Once the administrator has created the Persistent Volume, it can be used by your web application to store and retrieve data.
The best part about using a Persistent Volume is that your web application doesn’t have to worry about where the data is being stored or how it’s being managed. Kubernetes takes care of all the storage management behind the scenes, making it really easy for your application to use.
A Persistent Volume is a piece of storage that is provided by the Kubernetes administrator for your web application to store and retrieve data. It takes away the complexity of managing storage and makes it really easy for your application to use.
Persistent Volume Claim abbreviated as PVC
You have a web application that needs some storage to store data like images, videos, or documents. In Kubernetes, you can use a Persistent Volume Claim (PVC) to request this storage.
A Persistent Volume Claim is a request for storage that your web application makes to Kubernetes. When you create a PVC, you specify the amount and type of storage that your application needs. Once the PVC is created, Kubernetes automatically finds and binds a matching Persistent Volume (PV) to the claim.
The best part about using a PVC is that your web application doesn’t have to worry about where the storage is coming from or how it’s being managed. Kubernetes takes care of all the storage management behind the scenes, ensuring that your application has the storage it needs to function properly.
In short, Persistent Volume Claim is a request for storage that your web application makes to Kubernetes. It ensures that your application has the storage it needs to function properly, without worrying about the details of where the storage is coming from or how it’s being managed.
Summary Of The Kubernetes Objects
| Object | Description |
|---|---|
| HPA | Automatically scales the number of pods up or down based on resource utilization. Useful for handling spikes in traffic and optimizing resource usage. |
| PDB | Controls the number of replicated pods that can be taken down at the same time, ensuring that a minimum number of pods remain running at all times. |
| Job | Runs a one-off task by spinning up a dedicated pod to execute the task and terminating the pod automatically when the task is completed successfully. |
| CronJob | Allows you to schedule a job to run on a repeating schedule, making it really easy to automate repetitive tasks in your Kubernetes cluster. |
| PV | A piece of storage provided by the Kubernetes administrator that can be used by your web application to store and retrieve data. |
| PVC | A request for storage made by your web application to Kubernetes, which automatically finds and binds a matching Persistent Volume to the claim. |