KodeCloud CKAD Operators

Operators¶

Operators are pieces of software that ease the operational complexity of running another piece of software.
- It is a method of packaging, deploying, and managing a Kubernetes application.
Operators replace the human operator with a software operator.
- For example all the manual tasks that the DevOps team would do is packed into a software.
- For a stateful application like postgres or prometheus some tasks would be:
  - How to deploy the app
  - How to create a cluster of replicas
  - How to recover from failures
  - How to create backups
- A Kubernetes operator continues to monitor its application as it runs, and can back up data, recover from failures, and upgrade the application over time, automatically.
- Anything that is a part of an application lifecycle can be automated by the operator.
An operator packages CRD and its controller together.
- In order to do these things, the Operator uses Custom Resources (CR) that define the desired configuration and state of a specific application through Custom Resource Definitions (CRD).
Operators are mainly used for managing stateful applications and installing third party software like prometheus, grafana etc.
Operators builds upon the basic Kubernetes resource (using CRD) and controller concepts, but includes domain or application-specific knowledge to automate the entire life cycle of the software it manages.
Operators for a lot of software like elastic search, postgres, mysql have already been created for us.
- Artifact HUB – where we find both operators and helm charts (CNCF project)
- Operator Hub – dedicated exclusively to Operators (Redhat project)
Some popular k8s operators are: Prometheus, Grafana, Elastic Cloud on Kubernetes, RBAC Manager, Istio, ArgoCD.
If we want to create our own operators then we have to use the operator SDK or kubebuilder.
We can build custom operators using ansible playbooks, helm charts or go.
- There are different levels of capability that can be achieved using these theres.

Operators are best built by those that are experts in the business logic of installing, running, and upgrading a particular application.

Operators are generally deployed using helm charts.

Why should I use Operators when I can just use Helm charts for deploying applications?

Helm and Operators are to be used in different types of use cases.
With Helm you can package your applications. Just like an RPM package on Linux ! So you can continue to use Helm when deploying a simple application and when few customizations are required.
We need operators to perform actions described previously such as deploy stateful applications. It will then manage a set of instances, reconciling its state according to the mentioned specs of its CR.

References¶

Last updated: 2023-05-22