CSS provides log query and log backup, enabling you to easily manage and analyze logs to efficiently locate faults, optimize performance, and enhance system security.

Log query: On the log management page of the CSS management console, you can query the latest log records by node, log type, and other criteria, so you can quickly locate or diagnose issues.
Log backup: Cluster logs are periodically synchronized to OBS buckets. You can download them for in-depth analysis at any time. You can configure custom log backup policies by specifying backup schedules and storage locations. The system backs up all critical logs, including run logs, slow query logs, and deprecation logs. They provide comprehensive data for auditing and troubleshooting purposes.

Impact on Billing

When log backup is enabled, the generated log backups are stored in OBS buckets, which will result in additional costs. For details, see .

Prerequisites

The OBS bucket used for storing log backups has been created. The OBS bucket must meet the following requirements:

Storage Class: Standard or Warm.
Region: the same as that of the cluster.

Log Search

Log in to the CSS management console.
In the navigation pane on the left, choose Clusters > OpenSearch.
In the cluster list, click the name of the target cluster. The cluster information page is displayed.
Choose Logs > Log Search. The Log Search page is displayed.
You can search records by log type, node, log level, or keyword. For a detailed description of each type of logs, see Log Introduction.

When a log file reaches 128 MB or when the time reaches 00:00 UTC, the system automatically compresses and archives it. Only unarchived logs appear on the log search page, while archived logs remain accessible through the log backup function.

Log Backup

Cluster logs can be backed up to OBS buckets, where you can download them for in-depth analysis at any time.

Log in to the CSS management console.
In the navigation pane on the left, choose Clusters > OpenSearch.
In the cluster list, click the name of the target cluster. The cluster information page is displayed.
Choose Logs > Log Backup. The Log Backup page is displayed.

Enable log backup.

Perform the following steps to enable log backup. If it is already enabled, skip this step.

Click Enable Backup. In the displayed dialog box, configure necessary settings.

**Table 1** Log backup settings
Parameter	Description
OBS Bucket	Select an OBS bucket for storing log backups from the drop-down list box. If no OBS buckets meet your requirements, click Create Bucket to go to the OBS console and create one. For details, see Creating a Bucket. To grant an IAM user access to an OBS bucket, you need to grant the GetBucketStoragePolicy, GetBucketLocation, ListBucket, and ListAllMyBuckets permissions to that user.
Backup Path	Set the log storage location in the OBS bucket. The backup path cannot: Contain the following characters: *\:?"<>\|'{}** Start with a slash (/). Start or end with a period (.). Contain more than two consecutive slashes (/) or periods (.). Exceed 512 characters.
IAM Agency	To back up data to an OBS bucket, you must have the write permission to it. By configuring an IAM agency, you can authorize CSS to access its OBS resources through an associated account. If you are configuring an agency for the first time, click Automatically Create IAM Agency to create css-obs-agency. If there is an IAM agency automatically created earlier, you can click One-click authorization to have the OBS Administrator permissions deleted automatically, and have the following custom policies added automatically instead to implement more refined permissions control. "obs:bucket:GetBucketLocation", "obs:object:GetObjectVersion", "obs:object:GetObject", "obs:object:DeleteObject", "obs:bucket:HeadBucket", "obs:bucket:GetBucketStoragePolicy", "obs:object:DeleteObjectVersion", "obs:bucket:ListBucketVersions", "obs:bucket:ListBucket", "obs:object:PutObject" When OBS buckets use SSE-KMS encryption, the IAM agency must be granted KMS permissions. You can click Automatically Create IAM Agency and One-click authorization to have the following custom policies created automatically. "kms:cmk:create", "kms:dek:create", "kms:cmk:get", "kms:dek:decrypt", "kms:cmk:list" To use Automatically Create IAM Agency and One-click authorization, the following minimum permissions are required: "iam:agencies:listAgencies", "iam:roles:listRoles", "iam:agencies:getAgency", "iam:agencies:createAgency", "iam:permissions:listRolesForAgency", "iam:permissions:grantRoleToAgency", "iam:permissions:listRolesForAgencyOnProject", "iam:permissions:revokeRoleFromAgency", "iam:roles:createRole" To use an IAM agency, the following minimum permissions are required: "iam:agencies:listAgencies", "iam:agencies:getAgency", "iam:permissions:listRolesForAgencyOnProject", "iam:permissions:listRolesForAgency" WARNING: The agency name can contain only letters (case-sensitive), digits, underscores (_), and hyphens (-). Otherwise, the backup will fail.

Determine whether to enable Automatic backup based on service needs.

To enable automatic, periodic log backup, select Automatic backup, and set the backup policy. For more information, see Table 2.
If manual log backup is sufficient, deselect Automatic backup.

Click OK to enable log backup.
The configuration information will be displayed on the Log Backup tab.

Back up logs. Two options are available: automatic or manual.

Automatic log backup: Logs are backed up periodically based on the preset policy.

On the Log Backup page, click Modify Settings on the right.

In the Modify Settings dialog box, select Automatic backup, and configure the automatic backup policy.

**Table 2** Automatic backup settings
Parameter	Description
Time Zone	Select a time zone for the backup start time.
Backup Start Time	Specify the start time of auto backup. Select a value from the drop-down list. The value range is from 00:00 to 23:00. The backup always happens on the hour.

Click OK to enable automatic log backup.
Automatic log backup tasks are displayed in the task list. When Task Status in the task list changes to Succeeded, the backup is successful.

If log backup fails, click Failed Tasks learn the failure causes. A maximum of 10 failed tasks can be displayed. When log backup is disabled or the cluster is deleted, the failure records are also cleared.
If automatic log backup is not required, click Modify Settings. In the displayed dialog box, deselect Automatic backup, and click OK. In the displayed confirmation dialog box, click OK.
Disabling log backup does not automatically delete log backups automatically generated earlier. Instead, you need to manually delete them on the OBS console.

Manual log backup: Back up logs right away.

On the Log Backup page, click Back Up Manually under Log Backup Tasks.
In the displayed dialog box, confirm the log backup path and click OK.
The log backup task is displayed in the task list. When Task Status in the task list changes to Succeeded, the backup is successful.

If log backup fails, click Failed Tasks learn the failure causes. A maximum of 10 failed tasks can be displayed. When log backup is disabled or the cluster is deleted, the failure records are also cleared.

Check the backed-up log files.

Logs are backed up incrementally. After the backup is successful, you can access the target OBS bucket to obtain the full log files by clicking Log Path.

Table 3 lists the log types, where clustername indicates the cluster name.

**Table 3** Log types
Log Name	Description
clustername_deprecation.log	Deprecation log file
clustername_index_indexing_slowlog.log	Slow indexing log file
clustername_index_search_slowlog.log	Slow query log file
clustername.log	Run log file
clustername_access.log	Access log file

If the log backup function is no longer needed, you can disable it.
On the Log Backup page, click Disable Backup. In the displayed dialog box, click OK. Disabling log backup does not automatically delete existing log backups. Instead, you need to manually delete them on the OBS console.

Log Introduction

**Table 4** Log introduction
Log Type	Description	Purpose
Run logs	Run logs, or main logs, record the cluster status and key information about write and query operations. For example, write logs record operations such as index creation, index mapping update, and write queue exhaustion; and query logs record query queue status and query exceptions.	Check the status and write and query operations of each cluster node, including inter-node connectivity, full GC, index creation or deletion, and cluster-level query errors.
Slow indexing logs	Slow indexing logs record indexing operations (such as bulk, index, update, and delete) that took a long time to complete, helping you identify performance bottlenecks.	In the case of slow write performance, you can query slow indexing logs to locate the cause.
Slow query logs	Slow query logs record search requests that took a long time to complete. They help you monitor and analyze time-consuming search requests, so you can identify performance bottlenecks, optimize SQL queries, and improve overall system performance.	In the case of slow query performance, you can query slow query logs to locate the cause.
Deprecation logs	Deprecation logs record deprecation warnings. Deprecation warnings are written to this log when you use APIs, configurations, or functions that are marked for removal in future versions.	Check for APIs or features that are about to expire in future versions.
Access logs	Access logs record cluster access requests, such as the request path and source address. You cannot check access logs on the console. To check them, you need to back them up to an OBS bucket or transfer them to a target cluster first.	If there is a surge in service requests, you can analyze the request sources and paths by checking the access logs.

Run log description
Run logs record the cluster status and key information about write and query operations. For example, the log record below indicates that an index named test was created and afterwards the cluster status changed from YELLOW to GREEN.

Figure 1 Run log sample
Log content:
- 1. Log generation time
- 2. Log level, which can be DEBUG, INFO, WARN, or ERROR
- 3. Log-generating module
- 4. Name of the log-generating node
- 5. Log content
Slow indexing log description
Slow indexing logs record indexing operations that took a long time to complete. For example, the log record below shows an indexing request that lasted longer than the preset threshold. The log contains the index name, duration, and request content.

Figure 2 Slow indexing log sample
Log content:
- 1. Log generation time
- 2. Log level, which can be DEBUG, INFO, WARN, or ERROR
- 3. Log-generating module
- 4. Name of the log-generating node
- 5. Index name and ID
- 6. Log content. In this example, the log recorded the request execution duration, index type, and index request body.
Slow query log description
Slow query logs record search requests that took a long time to complete. For example, the log record below shows a search request that lasted longer than the preset threshold. The log contains the index name, duration, and request content.

Figure 3 Slow query log sample
Log content:
- 1. Log generation time
- 2. Log level, which can be DEBUG, INFO, WARN, or ERROR
- 3. Log-generating module
- 4. Name of the log-generating node
- 5. Index name and shard ID
- 6. Log content. In this example, the log recorded the query duration, number of hits, and query request body.
Deprecation log description
Deprecation logs record deprecation warnings. For example, the log record below indicates that GET /_cat/master has been deprecated and should be replaced with GET /_cat/cluster_manager.

Figure 4 Deprecation log sample
Log content:
- 1. Log generation time
- 2. Log level, which can only be DEPRECATION.
- 3. Log-generating module
- 4. Name of the log-generating node
- 5. Log content
Access log description
Access logs record cluster access requests and source addresses. For example, the log record below has recorded source information for the /_snapshot/my_backup/my_snapshot/_restore?pretty=true operation.

Figure 5 Access log sample
Log content:
- 1. Log generation time
- 2. Name of the log-generating node
- 3. Name of the log-generating thread
- 4. Log level, which can be DEBUG, INFO, WARN, or ERROR.
- 5. Log request method
- 6. Request path
- 7. Source and destination addresses of the request

FAQ: How Do I Change Log Levels?

Log4j2 is used as the log component in OpenSearch clusters. Multiple log levels (ERROR, WARN, INFO, DEBUG, and TRACE) are supported. The default log level is INFO. To facilitate troubleshooting and debugging, you can dynamically adjust the log levels.

INFO is the default log level. The levels, in order of increasing detail, are: ERROR, WARN, INFO, DEBUG, and TRACE. When INFO is set, you will see logs for itself and all higher-severity levels (ERROR and WARN), while more verbose levels (DEBUG and TRACE) are excluded.
You can change the log level of a specified module in real time via an OpenSearch API.

Example

Log in to OpenSearch Dashboards and go to the command execution page. OpenSearch clusters support multiple access methods. This topic uses OpenSearch Dashboards as an example to describe the operation procedures.
1. Log in to the CSS management console.
2. In the navigation pane on the left, choose Clusters > OpenSearch.
3. In the cluster list, find the target cluster, and click Dashboards in the Operation column to log in to OpenSearch Dashboards.
4. In the left navigation pane, choose Dev Tools.
  The left part of the console is the command input box, and the triangle icon in its upper-right corner is the execution button. The right part shows the execution result.

Run the following command to change the log level of the action module to DEBUG:

PUT _cluster/settings
{
  "persistent": {
    "logger": {
      "org.opensearch.action": "DEBUG"
    }
  }
}

Run the following command to restore the default log level INFO:

PUT _cluster/settings
{
  "persistent": {
    "logger": {
      "org.opensearch.action": null
    }
  }
}

FAQ: How Do I Enable Trace Logging?

To facilitate troubleshooting, debugging, and performance analysis, you may enable trace logging for the HTTP/Transport module and view detailed trace logs.

Enabling trace logging is a non-persistent configuration and will be disabled upon a cluster restart.

Operation Guide

Log in to OpenSearch Dashboards and go to the command execution page. OpenSearch clusters support multiple access methods. This topic uses OpenSearch Dashboards as an example to describe the operation procedures.
1. Log in to the CSS management console.
2. In the navigation pane on the left, choose Clusters > OpenSearch.
3. In the cluster list, find the target cluster, and click Dashboards in the Operation column to log in to OpenSearch Dashboards.
4. In the left navigation pane, choose Dev Tools.
  The left part of the console is the command input box, and the triangle icon in its upper-right corner is the execution button. The right part shows the execution result.

Run the following command to enable trace logging:

PUT _cluster/settings
{
  "transient": {
    "logger.org.opensearch.transport.TransportService.tracer": "trace",
    "transport.tracer.include": "",
    "http.tracer.include": "",
    "logger.org.opensearch.http.HttpTracer": "trace"
  }
}

Go to the log details page to view trace logs.
1. In the cluster list, click the name of the target cluster. The cluster information page is displayed.
2. Choose Logs > Log Search. The Log Search page is displayed.
3. Select all log levels (mandatory) and view trace logs.