5.5. Investigating pod issues

Procedure

1. Switch into a project:

   $ oc project <project_name>

2. List pods running within the namespace, as well as pod status, error states, restarts, and age:

   $ oc get pods

3. Determine whether the namespace is managed by a deployment configuration:

   $ oc status

   If the namespace is managed by a deployment configuration, the output includes the deployment configuration name and a base image reference.

4. Inspect the base image referenced in the preceding command’s output:

   $ skopeo inspect docker://<image_reference>

5. If the base image reference is not correct, update the reference in the deployment configuration:

   $ oc edit deployment/my-deployment

6. When deployment configuration changes on exit, the configuration will automatically redeploy. Watch pod status as the deployment progresses, to determine whether the issue has been resolved:

   $ oc get pods -w

7. Review events within the namespace for diagnostic information relating to pod failures:

   $ oc get events

Procedure

1. Query logs for a specific pod:

   $ oc logs <pod_name>

2. Query logs for a specific container within a pod:

   $ oc logs <pod_name> -c <container_name>

   Logs retrieved using the preceding oc logs commands are composed of messages sent to stdout within pods or containers.

3. Inspect logs contained in /var/log/ within a pod.

   1. List log files and subdirectories contained in /var/log within a pod:

      $ oc exec <pod_name> ls -alh /var/log

   2. Query a specific log file contained in /var/log within a pod:

      $ oc exec <pod_name> cat /var/log/<path_to_log>

   3. List log files and subdirectories contained in /var/log within a specific container:

      $ oc exec <pod_name> -c <container_name> ls /var/log

   4. Query a specific log file contained in /var/log within a specific container:

      $ oc exec <pod_name> -c <container_name> cat /var/log/<path_to_log>

Procedure

1. Switch into the project that contains the pod you would like to access. This is necessary because the oc rsh command does not accept the -n namespace option:

   $ oc project <namespace>

2. Start a remote shell into a pod:

   $ oc rsh <pod_name>  1

   1

   If a pod has multiple containers, oc rsh defaults to the first container unless -c <container_name> is specified.

3. Start a remote shell into a specific container within a pod:

   $ oc rsh -c <container_name> pod/<pod_name>

4. Create a port forwarding session to a port on a pod:

   $ oc port-forward <pod_name> <host_port>:<pod_port>  1

   1

   Enter Ctrl+C to cancel the port forwarding session.

Procedure

1. Start a debug pod with root access, based on a deployment.

   1. Obtain a project’s deployment name:

      $ oc get deployment -n <project_name>

   2. Start a debug pod with root privileges, based on the deployment:

      $ oc debug deployment/my-deployment --as-root -n <project_name>

2. Start a debug pod with root access, based on a deployment configuration.

   1. Obtain a project’s deployment configuration name:

      $ oc get deploymentconfigs -n <project_name>

   2. Start a debug pod with root privileges, based on the deployment configuration:

      $ oc debug deploymentconfig/my-deployment-configuration --as-root -n <project_name>

Procedure

1. Copy a file to a pod:

   $ oc cp <local_path> <pod_name>:/<path> -c <container_name>  1

   1

   The first container in a pod is selected if the -c option is not specified.

2. Copy a file from a pod:

   $ oc cp <pod_name>:/<path>  -c <container_name><local_path>  1

   1

   The first container in a pod is selected if the -c option is not specified.

   注意

   For oc cp to function, the tar binary must be available within the container.