Nginx-Ingress-Controller Fails to Start After AKS Upgrade to v1.22

Upgrading Kubernetes clusters is an essential practice to leverage the latest features and security enhancements. However, it can lead to temporary setbacks as well, especially when certain components fail to adapt to the new version. One such issue that administrators face is when the Nginx-Ingress-Controller fails to start after upgrading Azure Kubernetes Service (AKS) to version 1.22. Here's a technical dive into why this happens and how you can fix it.

Understanding the Problem

When AKS is upgraded to Kubernetes v1.22, certain deprecations and runtime changes can impact the operability of third-party components like the Nginx-Ingress-Controller. The failure typically manifests as pods that are stuck in a CrashLoopBackOff state, accompanied by error logs indicating misconfigurations or API incompatibilities.

Common Error Messages

Administrators may encounter error messages such as:

• Error: listener service not started
• Error: unable to recognize "": no matches for kind "Ingress" in version "networking.k8s.io/v1beta1"

Root Causes

1. API Version Deprecation

One of the critical changes in Kubernetes v1.22 is the removal of deprecated API versions. The Ingress API version networking.k8s.io/v1beta1 has been completely removed in favor of networking.k8s.io/v1. Any resources using the old API version will fail to deploy.

2. Missing or Mismatched Configurations

Another common reason is incompatible configuration files and misplaced secrets or configMaps required by the Nginx-Ingress-Controller. Ensure you are using updated and compatible configuration files post-upgrade.

3. Nginx-Ingress-Controller Version

An outdated version of the Nginx-Ingress-Controller also contributes to these issues. Ensure the controller version is compatible with Kubernetes v1.22. Commonly this involves upgrading to a version of the controller that explicitly supports the new Kubernetes API versions.

Solutions and Workarounds

1. Update Ingress API

Begin by inspecting your Ingress resources. Ensure that all YAML configurations are using the networking.k8s.io/v1 API version. Below is an example of an updated Ingress resource.

• host: example.com
  • path: /
• Check for Secrets: Ensure any SSL certificates or authentication data are correctly stored and accessible.
• ConfigMaps: Validate that any custom Nginx configurations are updated to reflect any changes in default settings or recommendations.