Fault Locating

On the details page of a workload, if an event is displayed indicating that the container fails to be started, perform the following steps to locate the fault:

1. Log in to the node where the abnormal workload is located.
2. Check the ID of the container where the workload pod exits abnormally.

   docker ps -a | grep $podName

3. View the logs of the corresponding container.

   docker logs $containerID

   Rectify the fault of the workload based on logs.

4. Check the error logs.

   cat /var/log/messages | grep $containerID  | grep oom

   Check whether the system OOM is triggered based on the logs.

Troubleshooting Process

Determine the cause based on the event information, as listed in Table 1.

In addition to the preceding possible causes, there are other three possible causes:

• Check Item 7: Whether the Container Startup Command Is Correctly Configured
• Check Item 8: Whether the Java Probe Version Is latest
• Check Item 9: Whether the User Service Has a Bug

Figure 1 Troubleshooting process

Check Item 1: Whether There Are Processes that Keep Running in the Container (Exit Code: 0)

1. Log in to the node where the abnormal workload is located.
2. View the container status.

   docker ps -a | grep $podName

   Example:

   

   If no running process exists in the container, the status code Exited (0) is displayed.

Check Item 2: Whether Health Check Fails to Be Performed (Exit Code: 137)

The health check configured for a workload is performed on services periodically. If an exception occurs, the pod reports an event and the pod fails to be restarted.

If the liveness-type (workload liveness probe) health check is configured for the workload and the number of health check failures exceeds the threshold, the containers in the pod will be restarted. On the workload details page, if Kubernetes events contain Liveness probe failed: Get http..., the health check fails.

Solution

On the workload details page, choose Upgrade > Advanced Settings > Health Check to check whether the health check policy is properly set and whether services are normal.

Check Item 3: Whether the Container Disk Space Is Insufficient

The following message refers to the Thin Pool disk that is allocated from the Docker disk selected during node creation. You can run the lvs command as user root to view the current disk usage.

Thin Pool has 15991 free data blocks which are less than minimum required 16383 free data blocks. Create more free space in thin pool or use dm.min_free_space option to change behavior

Solution

1. Release used disk space.

   docker rmi -f `docker images | grep myhuaweicloud | awk '{print $3}'` 

2. Expand the disk capacity. For details about how to expand the data disk capacity of a node, see Node Data Disk (Dedicated for Docker).

Check Item 4: Whether the Upper Limit of Container Resources Has Been Reached

If the upper limit of container resources has been reached, OOM will be displayed in the event details as well as in the log:

cat /var/log/messages | grep 96feb0a425d6 | grep oom

When a workload is created, if the requested resources exceed the configured upper limit, the system OOM is triggered and the container exits unexpectedly.

Check Item 5: Whether the Resource Limits Are Improperly Set for the Container

If the resource limits set for the container during workload creation are less than required, the container fails to be restarted.

Solution

Modify the container specifications of the workload. For details, see How Do I Set the Upper and Lower Limits of CPU and Memory Resources for a Container?.

Check Item 6: Whether the Container Ports in the Same Pod Conflict with Each Other

1. Log in to the node where the abnormal workload is located.
2. Check the ID of the container where the workload pod exits abnormally.

   docker ps -a | grep $podName

3. View the logs of the corresponding container.

   docker logs $containerID

   Rectify the fault of the workload based on logs. As shown in the following figure, container ports in the same pod conflict. As a result, the container fails to be started.

   Figure 2 Container restart failure due to a container port conflict
   

Solution

Re-create the workload and set a port number that is not used by any other pod.

Check Item 7: Whether the Container Startup Command Is Correctly Configured

The error messages are as follows:

Solution

Log in to the CCE console. On the workload details page, choose Upgrade > Advanced Settings > Lifecycle to check whether the startup command is correctly configured.

Check Item 8: Whether the Java Probe Version Is latest

The following figure shows the information of the Kubernetes event "Created container init-pinpoint".

Solution

1. When creating a Deployment or creating a StatefulSet, select the latest Java probe version (for example, 1.0.36, not the version latest) in the APM Settings area on the Advanced Settings page.

   

2. If the Java probe of the latest version has been selected during workload creation, click the workload name in the workload list. On the workload details page that is displayed, click the Workload O&M tab, click Edit under APM Settings, and select the latest Java probe version (for example, 1.0.36).

   

Check Item 9: Whether the User Service Has a Bug

Check whether the workload startup command is correctly executed or whether the workload has a bug.

1. Log in to the node where the abnormal workload is located.
2. Check the ID of the container where the workload pod exits abnormally.

   docker ps -a | grep $podName

3. View the logs of the corresponding container.

   docker logs $containerID

   Note: In the preceding command, containerID indicates the ID of the container that has exited.

   Figure 3 Incorrect startup command of the container
   

   As shown in the figure above, the container fails to be started due to an incorrect startup command. For other errors, rectify the bugs based on the logs.

Solution

Create a new workload and configure a correct startup command.