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kubernetes - How to debug crash-looping pods in OpenShift?

问题描述

I have a simple DeploymentConfig:

apiVersion: v1
kind: DeploymentConfig
metadata:
  name: my-dc
  labels:
    app: my
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: my
    spec:
      containers:
        - name: my
          image: image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic
          livenessProbe:
            exec:
              command:
                - echo
                - "I'm alive!"
              initialDelaySeconds: 10
          readinessProbe:
            exec:
              command:
                - echo
                - "I'm healthy!"
              initialDelaySeconds: 15
              periodSeconds: 15

The image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic image stream points to my own image that is simply:

FROM registry.access.redhat.com/rhel7/rhel-atomic

When I do oc create -f my-dc.yaml and try to check what is going on, I see that my pods are crash-looping.

To debug it, I did a oc status --suggest. It suggests listing the container logs with oc logs my-dc-1-z889c -c my. However, there is no logs for any of the containers.

My oc get events does not help either. It just cycles through these messages:

<unknown>   Normal    Scheduled                     pod/my-dc-1-vnhmp                     Successfully assigned pc/my-dc-1-vnhmp to ip-10-0-128-37.ec2.internal
31m         Normal    Pulling                       pod/my-dc-1-vnhmp                     Pulling image "image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic"
31m         Normal    Pulled                        pod/my-dc-1-vnhmp                     Successfully pulled image "image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic"
31m         Normal    Created                       pod/my-dc-1-vnhmp                     Created container my
31m         Normal    Started                       pod/my-dc-1-vnhmp                     Started container my
27m         Warning   BackOff                       pod/my-dc-1-vnhmp                     Back-off restarting failed container
<unknown>   Normal    Scheduled                     pod/my-dc-1-z8jgb                     Successfully assigned pc/my-dc-1-z8jgb to ip-10-0-169-70.ec2.internal
31m         Normal    Pulling                       pod/my-dc-1-z8jgb                     Pulling image "image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic"
31m         Normal    Pulled                        pod/my-dc-1-z8jgb                     Successfully pulled image "image-registry.openshift-image-registry.svc:5000/pc/rhel-atomic"
31m         Normal    Created                       pod/my-dc-1-z8jgb                     Created container my
31m         Normal    Started                       pod/my-dc-1-z8jgb                     Started container my
27m         Warning   BackOff                       pod/my-dc-1-z8jgb                     Back-off restarting failed container

How do I debug this? Why the containers crash?

I am using OpenShift Online.

标签： kubernetesopenshift

解决方案

似乎 pod 中的单个容器没有任何进程在运行。因此，容器在启动后立即终止。

保持容器运行的一个选项是将这些添加到容器的 DeploymentConfig 中：

        command:
        - /bin/sh
        stdin: true

/bin/sh根据图像中可用的内容，用不同的 shell（例如 bash）或从不同的位置替换。

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