Jenkins Master: 2.375.1

kubernetes-plugin: 3743.v1fa_4c724c3b_7

Kubernetes Client API: 5.12.2-193.v26a_6078f65a_9

EKS K8s version: 1.20

Jnlp container: `jenkins/inbound-agent:3107.v665000b_51092-4-jdk17`

Current setup

• Jenkins Master deployed to EC2 instance
• Jenkins agents getting dispatched to k8s worker nodes
• All infra runs on AWS

Problem Statement

Jenkins agent pod containing >1 container occasionally run into the following error when a command is dispatched to a non-jnlp container.

Caused by: java.net.ProtocolException: Expected HTTP 101 response but was '401 '
at okhttp3.internal.ws.RealWebSocket.checkResponse(RealWebSocket.java:229)
at okhttp3.internal.ws.RealWebSocket$2.onResponse(RealWebSocket.java:196)
... 5 more
Retrying...
Failed to start websocket connection: io.fabric8.kubernetes.client.KubernetesClientException: An error has occurred. 

Current Workaround

Cordoning off the underlying k8s worker node seems to consistently address the issue. But obviously not scalable