Collecting Data Plane Logs

Billing

LTS does not charge you for creating log groups and offers a free quota for log collection every month. You pay only for log volume that exceeds the quota.

Control Plane Components

There are two control plane log types. Each log stream corresponds to a component of the Kubernetes control plane. To learn more about these components, see Kubernetes Components.

Log Collection

1. View and configure log collection policies.
   1. Log in to the UCS console, choose Fleets, and click the fleet name to access the fleet details page. Choose Container Clusters, click the cluster name to access the cluster details page, and choose Logging.

   2. Click View Log Collection Policies in the upper right corner.

      All log collection policies reported to LTS are displayed.

      Figure 1 Viewing log collection policies
      

      If Container standard output and Kubernetes events are selected during add-on installation, two log collection policies will be created, and the collected logs will be reported to the default log group and log streams.

   3. Click Create Log Policy and configure parameters as required.

      Policy Template: If no log collection policy is selected during add-on installation or the log collection policy is deleted, you can use this option to create a default log collection policy.

      Figure 2 Policy template
      

      Custom Policy: You can use this option to create custom log collection policies.

      Figure 3 Custom policy
      

      Table 2 Custom policy parameters

      Parameter	Description
      Log Type	Type of logs to be collected. Container standard output: used to collect container standard output logs. You can create a log collection policy by namespace, workload name, or instance label. Container file log: used to collect text logs. You can create a log collection policy by workload or instance label. Node file log: used to collect logs from a node. Only one file path can be configured for a log collection policy.
      Log Source	Containers whose logs are to be collected. All containers: You can specify all containers in a namespace. If this parameter is not specified, logs of containers in all namespaces will be collected. Workload: You can specify a workload and its containers. If this parameter is not specified, logs of all containers running the workload will be collected. Workload with target label: You can specify a workload by label and its containers. If this parameter is not specified, logs of all containers running the workload will be collected.
      Collection Path	Path of files where logs are to be collected. The path must start with a slash (/) and contain a maximum of 512 characters. Only uppercase letters, lowercase letters, digits, hyphens (-), underscores (_), slashes (/), asterisks (*), and question marks (?) are allowed. The file name can contain only uppercase letters, lowercase letters, digits, hyphens (-), underscores (_), asterisks (*), question marks (?), and periods (.). Enter an absolute path for the log directory. Logs in the format of .gz, .tar, and .zip are not supported. A maximum of three levels of directories can be matched using wildcards. The level-1 directory does not support wildcards. The directory name and file name must be complete names and support asterisks (*) and question marks (?) as wildcards. An asterisk (*) can match multiple characters. A question mark (?) can match only one character. Example: If the directory is /var/logs/* and the file name is *.log, any log files with the extension .log in all directories in the /var/logs directory will be reported. If the directory is /var/logs/app_* and the file name is *.log, any log files with the extension .log in all directories that match app_* in the /var/logs directory will be reported. If a volume is attached to the data directory of a service container, this add-on cannot collect data from the parent directory. In this case, you need to configure a complete data directory. For example, if the data volume is attached to the /var/log/service directory, logs cannot be collected from the /var/log or /var/log/* directory. In this case, you need to set the collection directory to /var/log/service.
      Log Format	Single-line Each log contains only one line of text. The newline character \n denotes the start of a new log. Multi-line Some programs (for example, Java program) print a log that occupies multiple lines. By default, logs are collected by line. If you want to display logs as a single message, you can enable multi-line logging and use the regular pattern. If you select the multi-line text, you need to enter the log matching format. Example: If logs need to be collected by line, enter \d{4}-\d{2}-\d{2} \d{2}\:\d{2}\:\d{2}.*. The following three lines starting with the date are regarded as a log. 2022-01-01 00:00:00 Exception in thread "main" java.lang.RuntimeException: Something has gone wrong, aborting! at com.myproject.module.MyProject.badMethod(MyProject.java:22) at com.myproject.module.MyProject.oneMoreMethod(MyProject.java:18)
      Report to LTS	This parameter is used to configure the log group and log stream for log reporting. Default log groups/log streams: The default log group (k8s-log-{Cluster ID}) and default log stream (stdout-{Cluster ID}) are automatically selected. Custom log groups/log streams: You can select any log group and log stream.
      Log Group	A log group is the basic unit for LTS to manage logs. If you do not have a log group, CCE prompts you to create one. The default name is k8s-log-{Cluster ID}, for example, k8s-log-bb7eaa87-07dd-11ed-ab6c-0255ac1001b3.
      Log Stream	A log stream is the basic unit for log read and write. You can create log streams in a log group to store different types of logs for finer log management. When you install the add-on or create a log policy based on a template, the following log streams are automatically created: stdout-{Cluster ID} for container logs, for example, stdout-bb7eaa87-07dd-11ed-ab6c-0255ac1001b3 event-{Cluster ID} for Kubernetes events, for example, event-bb7eaa87-07dd-11ed-ab6c-0255ac1001b3

   4. Click Edit to modify an existing log collection policy.
   5. Click Delete to delete an existing log collection policy.

2. View the logs.
   1. On the UCS console, choose Fleets and click the fleet name to access the fleet details page. Choose Container Clusters, click the cluster name to access the cluster details page, and choose Logging.
   2. View different types of logs:
      • Container Logs: displays all logs in the default log stream stdout-{Cluster ID} of the default log group k8s-log-{Cluster ID}. You can search for logs by workload for a Huawei Cloud cluster.
        Figure 4 Querying container logs
        
      • Kubernetes Events: displays all Kubernetes events in the default log stream event-{Cluster ID} of the default log group k8s-log-{Cluster ID}.
      • Control Plane Logs: displays all logs of components on the control plane in the default log stream {Component name}-{Cluster ID} of the default log group k8s-log-{Cluster ID}.
      • Control Plane Audit Logs: displays all control plane audit logs in the default log stream audit-{Cluster ID} of the default log group k8s-log-{Cluster ID}.
      • Global Log Query: You can view logs in the log streams of all log groups. You can specify a log stream to view the logs. By default, the default log group k8s-log-{Cluster ID} is selected. You can click the edit icon on the right of Switching Log Groups to switch to another log group.
        Figure 5 Global log query
        
   3. Click View Log Collection Policies in the upper right corner. Locate the log collection policy and click View Log to go to the log list.
      Figure 6 Viewing logs
      

Troubleshooting

1. "Failed to create log group, the number of log groups exceeds the quota" is reported in the standard output log of log-operator.

   Example:

   2023/05/05 12:17:20.799 [E] call 3 times failed, resion: create group failed, projectID: xxx, groupName: k8s-log-xxx, err: create groups status code: 400, response: {"error_code":"LTS.0104","error_msg":"Failed to create log group, the number of log groups exceeds the quota"}, url: https://lts.cn-north-4.myhuaweicloud.com/v2/xxx/groups, process will retry after 45s

   Solution: On the LTS console, delete unnecessary log groups. For details about the quota limit of log groups, see Log Groups.

2. A container file path is configured but is not mounted to the container, and Docker is used as the container engine. As a result, logs cannot be collected.

   Solution:

   Check whether Device Mapper is used for the node where the workload resides. Device Mapper does not support text log collection. (This restriction has been displayed when you create a log collection policy, as shown in Figure 7.) To check this, perform the following operations:

   1. Go to the node where the workload resides.
   2. Run the docker info | grep "Storage Driver" command.
   3. If the value of Storage Driver is devicemapper, text logs cannot be collected.
   Figure 7 Creating a log policy
   
3. Logs cannot be reported, and "log's quota has full" is reported in the standard output log of the OTel component.

   

   Solution:

   LTS provides a free log quota. If the quota is used up, you will be billed for the excess log usage. If an error message is displayed, the free quota has been used up. To continue collecting logs, log in to the LTS console, choose Configuration Center > Quota Configuration, and enable Continue to Collect Logs When the Free Quota Is Exceeded.

4. Text logs cannot be collected because wildcards are configured for the collection directory.

   Troubleshooting: Check the volume mounting status in the workload configuration. If a volume is attached to the data directory of a service container, this add-on cannot collect data from the parent directory. In this case, you need to set the collection directory to a complete data directory. For example, if the data volume is attached to the /var/log/service directory, logs cannot be collected from the /var/log or /var/log/* directory. In this case, you need to set the collection directory to /var/log/service.

   Solution: If the log generation directory is /application/logs/{Application name}/*.log, attach the data volume to the /application/logs directory and set the collection directory in the log collection policy to /application/logs/*/*.log.