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Monitor Azure Cosmos DB for MongoDB vCore diagnostics logs with Azure Monitor

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APPLIES TO: MongoDB vCore

Azure's diagnostic logs are essential to capture Azure resource logs for an Azure Cosmos DB for MongoDB vCore account. These logs furnish detailed and frequent insights into the operations for resources with the account.

Important

This feature is not available with M25 (burstable) or M30 (free-tier) SKUs.

Prerequisites

Create diagnostic settings

Platform metrics and Activity logs are gathered automatically. To collect resource logs and route them externally from Azure Monitor, you must establish a diagnostic setting. When you activate diagnostic settings for Azure Cosmos DB accounts, you must choose to route them to either a Log Analytics workspace or an Azure Storage account.

  1. Create shell variables for clusterName and resourceGroupName.

    # Variable for API for MongoDB vCore cluster resource
clusterName="<resource-name>"

# Variable for resource group
resourceGroupName="<resource-group-name>"

  2. Create shell variables for workspaceName and diagnosticSettingName,

    # Variable for workspace name
workspaceName="<storage-account-name>"

# Variable for diagnostic setting name
diagnosticSettingName="<diagnostic-setting-name>"

    Note

    For example, if the Log Analytics workspace's name is test-workspace and the diagnostic settings' name is test-setting:

    workspaceName="test-workspace"
diagnosticSettingName:"test-setting"

  3. Get the resource identifier for the API for MongoDB vCore cluster.

    az cosmosdb mongocluster show \
    --resource-group $resourceGroupName \
    --cluster-name $clusterName

clusterResourceId=$(az cosmosdb mongocluster show \
    --resource-group $resourceGroupName \
    --cluster-name $clusterName \
    --query "id" \
    --output "tsv" \
)

  4. Get the resource identifier for the Log Analytics workspace.

    az monitor log-analytics workspace show \
    --resource-group $resourceGroupName \
    --name $workspaceName

workspaceResourceId=$(az monitor log-analytics workspace show \
    --resource-group $resourceGroupName \
    --name $workspaceName \
    --query "id" \
    --output "tsv" \
)

  5. Use az monitor diagnostic-settings create to create the setting.

    az monitor diagnostic-settings create \
    --resource-group $resourceGroupName \
    --name $diagnosticSettingName \
    --resource $clusterResourceId \
    --export-to-resource-specific true \
    --logs '[{category:vCoreMongoRequests,enabled:true,retention-policy:{enabled:false,days:0}}]' \
    --workspace $workspaceResourceId

    Important

    By enabling the --export-to-resource-specific true setting, you ensure that the API for MongoDB vCore request log events are efficiently ingested into the vCoreMongoRequests table specifically designed with a dedicated schema.

    In contrast, neglecting to configure --export-to-resource-specific true would result in the API for MongoDB vCore request log events being routed to the general AzureDiagnostics table.

    It's important to note that when creating the diagnostic setting through the Portal, log events will currently flow to the AzureDiagnostics table. For customers who prefer exporting logs to the resource-specific VCoreMongoRequests table, utilizing the Azure CLI with the --export-to-resource-specific true option is recommended.

Manage diagnostic settings

Sometimes you need to manage settings by finding or removing them. The az monitor diagnostic-settings command group includes subcommands for the management of diagnostic settings.

  1. List all diagnostic settings associated with the API for MongoDB vCore cluster.

    az monitor diagnostic-settings list \
    --resource-group $resourceGroupName \
    --resource $clusterResourceId

  2. Delete a specific setting using the associated resource and the name of the setting.

    az monitor diagnostic-settings delete \
    --resource-group $resourceGroupName \
    --name $diagnosticSettingName \
    --resource $clusterResourceId

Use advanced diagnostics queries

Use these resource-specific queries to perform common troubleshooting research in an API for MongoDB vCore cluster.

Important

This section assumes that you are using a Log Analytics workspace with resource-specific logs.

  1. Navigate to Logs section of the API for MongoDB vCore cluster. Observe the list of sample queries.

    Screenshot of the diagnostic queries list of sample queries.

  2. Run this query to count the number of failed API for MongoDB vCore requests grouped by error code.

    VCoreMongoRequests
// Time range filter:  | where TimeGenerated between (StartTime .. EndTime)
// Resource id filter: | where _ResourceId == "/subscriptions/00000000-0000-0000-0000-000000000000/resourcegroups/my-resource-group-name/providers/microsoft.documentdb/mongoclusters/my-cluster-name"
| where ErrorCode != 0
| summarize count() by bin(TimeGenerated, 5m), ErrorCode=tostring(ErrorCode)

  3. Run this query to get the API for MongoDB vCore requests P99 runtime duration by operation name.

    // Mongo vCore requests P99 duration by operation 
// Mongo vCore requests P99 runtime duration by operation name. 
VCoreMongoRequests
// Time range filter:  | where TimeGenerated between (StartTime .. EndTime)
// Resource id filter: | where _ResourceId == "/subscriptions/00000000-0000-0000-0000-000000000000/resourcegroups/my-resource-group-name/providers/microsoft.documentdb/mongoclusters/my-cluster-name"
| summarize percentile(DurationMs, 99) by bin(TimeGenerated, 1h), OperationName

  4. Run this query to get the count of API for MongoDB vCore requests grouped by total runtime duration.

    // Mongo vCore requests binned by duration 
// Count of Mongo vCore requests binned by total runtime duration. 
VCoreMongoRequests
// Time range filter:  | where TimeGenerated between (StartTime .. EndTime)
// Resource id filter: | where _ResourceId == "/subscriptions/00000000-0000-0000-0000-000000000000/resourcegroups/my-resource-group-name/providers/microsoft.documentdb/mongoclusters/my-cluster-name"
| project TimeGenerated, DurationBin=tostring(bin(DurationMs, 5))
| summarize count() by bin(TimeGenerated, 1m), tostring(DurationBin)

  5. Run this query to get the count of API for MongoDB vCore requests by user agent.

    // Mongo vCore requests by user agent 
// Count of Mongo vCore requests by user agent. 
VCoreMongoRequests
// Time range filter:  | where TimeGenerated between (StartTime .. EndTime)
// Resource id filter: | where _ResourceId == "/subscriptions/00000000-0000-0000-0000-000000000000/resourcegroups/my-resource-group-name/providers/microsoft.documentdb/mongoclusters/my-cluster-name"
| summarize count() by bin(TimeGenerated, 1h), UserAgent

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