Kube No Trouble: Identifying Deprecated APIs in Kubernetes

Kubernetes (K8s) has become the de facto standard for container orchestration, enabling developers and operators to easily deploy, manage, and scale containerized applications. However, as with any rapidly evolving technology, Kubernetes frequently introduces new features, deprecates old ones, and makes breaking changes. One common challenge users face is identifying and managing deprecated APIs.

Keeping our clusters up-to-date with the latest Kubernetes versions is crucial to addressing bugs and security vulnerabilities. However, the update process in Kubernetes clusters, especially in production clusters, may not be straightforward. In this blog post, we’ll explore how to identify deprecated APIs in your Kubernetes clusters.

Understanding API Deprecation in Kubernetes

Kubernetes follows a well-defined API versioning and deprecation policy to ensure a smooth transition for users. Each API is versioned using a combination of major, minor, and patch versions (e.g., v1, v1beta1, v1alpha1). When a new version of an API is introduced, the old version is marked as deprecated and is typically supported for a few more releases before being removed entirely.

Why is it Important to Identify Deprecated APIs?

Using deprecated APIs can lead to several issues:

1. Security Risks: Deprecated APIs may not receive security updates, leaving your cluster vulnerable.
2. Stability Issues: Older APIs might not be as stable or performant as newer ones.
3. Maintenance Overhead: Keeping up with Kubernetes upgrades becomes harder if you’re relying on deprecated APIs.
4. Future-Proofing: Ensuring your codebase uses supported APIs makes it easier to adopt new features and improvements.

Tools and Techniques to Identify Deprecated APIs

1. Kubectl Deprecation Warnings

Kubernetes’ command-line tool, kubectl, can be used to identify deprecated APIs. When you apply or create resources using deprecated APIs, kubectl often emits warnings. For example:

kubectl apply -f my-deployment.yaml

Warning: extensions/v1beta1 Deployment is deprecated in v1.16+, unavailable in v1.22+; use apps/v1 Deployment

2. Kube-No-Trouble (Kubent)

Kube-No-Trouble (kubent) is a powerful tool designed to detect deprecated and removed Kubernetes APIs. It scans your cluster and provides detailed reports on deprecated API usage. Here’s how to use it:

1. Install Kube-No-Trouble:

$ curl -sfL https://raw.githubusercontent.com/doitintl/kube-no-trouble/main/install.sh | sh

2. Run Kube-No-Trouble:

$ kubent

This command scans your cluster and outputs deprecated API usage, helping you identify resources that need updating.

Example:

$./kubent
6:25PM INF >>> Kube No Trouble `kubent` <<<
6:25PM INF Initializing collectors and retrieving data
6:25PM INF Retrieved 103 resources from collector name=Cluster
6:25PM INF Retrieved 0 resources from collector name="Helm v3"
6:25PM INF Loaded ruleset name=deprecated-1-16.rego
6:25PM INF Loaded ruleset name=deprecated-1-20.rego
__________________________________________________________________________________________
>>> 1.16 Deprecated APIs <<<
------------------------------------------------------------------------------------------
KIND         NAMESPACE     NAME                    API_VERSION
Deployment   default       nginx-deployment-old    apps/v1beta1
Deployment   kube-system   event-exporter-v0.2.5   apps/v1beta1
Deployment   kube-system   k8s-snapshots           extensions/v1beta1
Deployment   kube-system   kube-dns                extensions/v1beta1
__________________________________________________________________________________________
>>> 1.20 Deprecated APIs <<<
------------------------------------------------------------------------------------------
KIND      NAMESPACE   NAME           API_VERSION
Ingress   default     test-ingress   extensions/v1beta1

Automating the Detection and Update Process

To streamline the process of detecting and updating deprecated APIs, consider integrating the following steps into your CI/CD pipeline:

1. Run Kube-No-Trouble as part of your build process to detect deprecated APIs.
2. Generate Reports and alert your team of any deprecated API usage.
3. Automate Fixes where possible using scripts or Kubernetes operators to update resources to supported API versions.
4. Run Integration Tests to ensure that the updates do not break existing functionality.

Conclusion

Keeping up with Kubernetes API changes is crucial for maintaining the security, stability, and future-proofing of your clusters. By leveraging tools like kubectl and Kube-No-Trouble, you can efficiently identify and manage deprecated APIs.

Thanks for reading this far!! We appreciate your comments and feedback.

About The Author
Suraj Solanki
Senior DevOps Engineer
LinkedIn: https://www.linkedin.com/in/suraj-solanki