Access logs

The KubeBlocks log enhancement function aims to simplify troubleshooting. With kbcli, the command line tool of KubeBlocks, you can view all kinds of logs generated by the database clusters running on KubeBlocks, such as slow logs, error logs, audit logs, and the container running logs (Stdout and Stderr). For Redis, only the running log is supported.

The KubeBlocks log enhancement function uses methods similar to kubectl exec and kubectl logs to ensure a self-closed loop and lightweight.

Before you start

• The container image supports tail and xargs commands.
• Install KubeBlocks: You can install KubeBlocks by kbcli or by Helm.
• In this guide, we take the MySQL engine as an example, the operation is the same for all database engines.

Steps

1. Enable the log enhancement function.

   • Enable this function when creating a cluster.

     • If you create a cluster by running the kbcli cluster create command, add the --enable-all-logs=true option to enable the log enhancement function. When this option is true, all the log types defined by spec.componentDefs.logConfigs in ClusterDefinition are enabled automatically.

       kbcli cluster create mysql --enable-all-logs=true mycluster

   • Update this cluster if you did not enable it when creating a cluster.

     kbcli cluster update mycluster --enable-all-logs=true -n <namespace>
     note

     The default namespace in which a cluster is created is default. If you specify a namespace when creating a cluster, fill in <namespace> with your customized one.

2. View the supported logs.

   Run the kbcli cluster list-logs command to view the enabled log types of the target cluster and the log file details. INSTANCE of each node is displayed.

   Example

   kbcli cluster list-logs mycluster
   >
   INSTANCE                     LOG-TYPE        FILE-PATH                                   SIZE        LAST-WRITTEN                          COMPONENT
   mycluster-mysql-0        error           /data/mysql/log/mysqld-error.log            6.4K        Feb 06, 2023 09:13 (UTC+00:00)        mysql
   mycluster-mysql-0        general         /data/mysql/log/mysqld.log                  5.9M        Feb 06, 2023 09:13 (UTC+00:00)        mysql
   mycluster-mysql-0        slow            /data/mysql/log/mysqld-slowquery.log        794         Feb 06, 2023 09:13 (UTC+00:00)        mysql       

3. Access the cluster log file.

   Run the kbcli cluster logs command to view the details of the target log file generated by the target instance on the target cluster. You can use different options to view the log file details you need. You can also run kbcli cluster logs -h to see the examples and option descriptions.

   kbcli cluster logs -h
   Output

   Access cluster log file
   
   Examples:
     # Return snapshot logs from cluster mycluster with default primary instance (stdout)
     kbcli cluster logs mycluster
   
     # Display only the most recent 20 lines from cluster mycluster with default primary instance (stdout)
     kbcli cluster logs --tail=20 mycluster
   
     # Return snapshot logs from cluster mycluster with specify instance my-instance-0 (stdout)
     kbcli cluster logs mycluster --instance my-instance-0
   
     # Return snapshot logs from cluster mycluster with specify instance my-instance-0 and specify container
     # my-container (stdout)
     kbcli cluster logs mycluster --instance my-instance-0 -c my-container
   
     # Return slow logs from cluster mycluster with default primary instance
     kbcli cluster logs mycluster --file-type=slow
   
     # Begin streaming the slow logs from cluster mycluster with default primary instance
     kbcli cluster logs -f mycluster --file-type=slow
   
     # Return the specify file logs from cluster mycluster with specify instance my-instance-0
     kbcli cluster logs mycluster --instance my-instance-0 --file-path=/var/log/yum.log
   
     # Return the specify file logs from cluster mycluster with specify instance my-instance-0 and specify
     # container my-container
     kbcli cluster logs mycluster --instance my-instance-0 -c my-container --file-path=/var/log/yum.log

4. (Optional) Troubleshooting.

   The log enhancement function does not affect the core process of KubeBlocks. If a configuration exception occurs, a warning shows to help troubleshoot. warning is recorded in the event and status.Conditions of the target database cluster.

   View warning information.

   • Run kbcli cluster describe <cluster-name> to view the status of the target cluster. You can also run kbcli cluster list events <cluster-name> to view the event information of the target cluster directly.

     kbcli cluster describe mycluster

     kbcli cluster list-events mycluster

   • Run kubectl describe cluster <cluster-name> to view the warning.

     kubectl describe cluster mycluster

     Example

     Status:
       Cluster Def Generation:  3
       Components:
           Replicasets:
             Phase:  Running
       Conditions:
         Last Transition Time:  2022-11-11T03:57:42Z
         Message:               EnableLogs of cluster component replicasets has invalid value [errora slowa] which isn't defined in cluster definition component replicasets
         Reason:                EnableLogsListValidateFail
         Status:                False
         Type:                  ValidateEnabledLogs
       Observed Generation:     2
       Operations:
         Horizontal Scalable:
             Name:  replicasets
         Restartable:
           replicasets
         Vertical Scalable:
           replicasets
       Phase:  Running
     Events:
       Type     Reason                      Age   From                Message
       ----     ------                      ----  ----                -------
       Normal   Creating                    49s   cluster-controller  Start Creating in Cluster: release-name-error
       Warning  EnableLogsListValidateFail  49s   cluster-controller  EnableLogs of cluster component replicasets has invalid value [errora slowa] which isn't defined in cluster definition component replicasets
       Normal   Running                     36s   cluster-controller  Cluster: release-name-error is ready, current phase is Running