Logging is a crucial aspect of any application, including those built with Microsoft Azure Cosmos DB. It provides in-depth insight into how the application behaves, both in development and in a production environment. It is essential to enable the Software Development Kit (SDK) logging to maximize the performance and troubleshoot any issues quickly.
Enabling Logging in Cosmos DB SDK
The Azure Cosmos DB SDK contains built-in logging functionalities that help developers trace the progress of operations, capture any exceptions, and monitor performance metrics for optimization.
To enable SDK logging, you need to configure the client set up. Here’s an example using CosmosClientOptions in .Net SDK:
CosmosClientOptions clientOptions = new CosmosClientOptions()
{
TraceEnabled = true
};
CosmosClient client = new CosmosClient("
Database database = client.GetDatabase("
Upon setting TraceEnabled as true, the SDK starts logging operation trace data, which could be helpful to diagnosing issues or troubleshooting.
Levels of Logging
The SDK provides several levels of logging, each offering a different degree of detail about the system’s operations.
- Error: Logs only when errors occur. This is the lowest, least verbose level.
- Warning: Logs when warnings are issued.
- Info: Logs when significant events are occurring in the system.
- Debug: Logs detailed debug information, useful during development and debugging.
- Verbose: Logs everything, including protocol information. This is the highest, most verbose level.
Typically, the “Info” level is suitable for production systems, while the “Debug” and “Verbose” levels are more utilized during development and troubleshooting.
Viewing and Analyzing Logs
To effectively monitor and troubleshoot any possible issues, developers should review the logs periodically. With SDK logging enabled, logs can be accessed through Azure Monitor Logs or Log Analytics. It’s also possible to route SDK logs to different targets using Diagnostic settings.
The logs provide detailed information, including the time taken by each operation, the status of the request, and even the query statistics in the case of read or write operations. Analyzing this data can provide significant insights into improving application performance and reliability.
Enabling Logging in Java SDK
For Java SDK, logging can be enabled on a more detailed level utilizing SLF4J.
System.setProperty("azure.cosmos.logging.level", "INFO");
System.setProperty("azure.cosmos.userAgentSuffix", "-my-custom-suffix");
CosmosClientBuilder clientBuilder = new CosmosClientBuilder()
.endpoint("
.key("
This example specifies “INFO” as logging level. Change this to any other level like “DEBUG”, “ERROR”, “WARN” and “VERBOSE” to specify other logging levels.
Key Takeaways
Enabling SDK logging in Azure Cosmos DB is a critical step in monitoring your application’s behavior and performance. Developers can quickly diagnose and rectify issues, and provide continuous robust service. Always remember, the choice of logging level should align with your needs for detail and system performance, as higher verbosity levels incur higher system overhead.
Make sure to review logs frequently, and understand the information contained within, to maintain optimal performance for your Cosmos DB applications.
Practice Test
True/False: Azure Cosmos DB SDK logging can be enabled to debug errors and performance issues.
- True
- False
Answer: True
Explanation: SDK logging in Azure Cosmos DB can indeed be enabled to support debugging efforts, monitor performance trends, and troubleshoot problems.
True/False: Once SDK logging is turned on, it cannot be turned off.
- True
- False
Answer: False
Explanation: You can disable SDK logging after it’s enabled. It’s recommended to turn it off once you’re finished debugging to avoid adding unnecessary load to your system.
Multiple Select: Which of the following types of information do SDK logs provide?
- A) Request/Response activity
- B) Performance metrics
- C) API calls
- D) DNS lookups
Answer: A, B, C
Explanation: Azure Cosmos’s DB SDK logging provides information regarding request/response activity, performance metrics, and API calls to help with debugging and performance tracking. DNS lookups are not part of the SDK logs.
Single Select: What logging level should be used to retrieve only error logs from Azure Cosmos DB SDK?
- A) Information
- B) Warning
- C) Error
- D) Debug
Answer: C) Error
Explanation: The Error level logging produces logs only when an error occurs. This level is generally used to log errors during the execution which are harmful and may cause the application not to function properly.
True/False: SDK logging can be implemented natively in Azure Cosmos DB without any third-party extensions.
- True
- False
Answer: True
Explanation: Indeed, Azure Cosmos DB has native support for SDK logging. There is no need to use third-party extensions for this.
Single Select: Which version of Azure Cosmos DB SDK introduced latency metrics in SDK logs?
- A) V1
- B) V2
- C) V3
- D) V4
Answer: C) V3
Explanation: Starting from the V3 SDK, Azure Cosmos DB includes latency metrics for every operation in SDK logs.
Multiple Select: Which of these can be logged using Azure Cosmos DB SDK logging?
- A) HTTP Headers
- B) Query Metrics
- C) DNS Lookups
- D) Connection Metrics
Answer: A, B, D
Explanation: HTTP Headers, Query metrics, and Connection metrics can be logged using Azure Cosmos DB SDK logging. DNS lookups are not logged.
Single Select: Which language’s SDK does not support SDK logging?
- A) Javascript
- B) Python
- C) .NET
- D) All support SDK logging
Answer: D) All support SDK logging
Explanation: All of the Azure Cosmos DB SDKs for Python, JavaScript and .NET support SDK logging.
True/False: Enabling SDK logging adversely affects the latency and throughput of your application.
- True
- False
Answer: True
Explanation: While SDK logging is useful for diagnosis, it can have a slight impact on the latency and throughput because logging operations add overhead to the application.
Single Select: What type of logging level does Azure Cosmos DB recommend for production deployments?
- A) Verbose
- B) Information
- C) Warning
- D) None
Answer: C) Warning
Explanation: The warning level is recommended for most production systems because it will only log events that could potentially cause issues, without cluttering logs with regular operation status updates.
True/False: Azure Cosmos DB SDK logs can be exported to Application Insights.
- True
- False
Answer: True
Explanation: Azure Cosmos DB supports exporting SDK logs to Application Insights, allowing for broader analytics and monitoring capabilities.
Multiple Select: What components do the Azure Cosmos DB SDK logs contain?
- A) Request rate
- B) Resource type
- C) Resources consumed in RU
- D) All of the above
Answer: D) All of the above
Explanation: The Azure Cosmos DB SDK logs contain detailed information about the request rate, the type of the resource being accessed, and the resources used in terms of Request Units (RU).
True/False: SDK logs in Azure Cosmos DB are stored permanently.
- True
- False
Answer: False
Explanation: Log data is not stored permanently and has a set retention period. After this period, the data is automatically deleted.
Single Select: What should be the minimum logging level for Azure Cosmos DB SDK to log dependency calls?
- A) Information
- B) Warning
- C) Error
- D) Debug
Answer: A) Information
Explanation: Dependency calls require a minimum logging level of Information in order to be captured in the SDK logs.
Multiple Select: What information does the API operation log in Azure Cosmos DB SDK logging provide?
- A) Number of retries
- B) Request URI
- C) Status code
- D) All of the above
Answer: D) All of the above
Explanation: The API operation log provides these details: total execution time, request charge, HTTP method, request URI, status code, and number of retries among others.
Interview Questions
What is SDK Logging in the context of Azure Cosmos DB?
SDK logging in Azure Cosmos DB allows you to capture data about the operations executed by the SDK. This can be greatly useful when troubleshooting issues or when monitoring the performance of your applications.
How do you enable SDK logging in .NET Version 3 or higher?
In .NET Version 3 or higher, you can enable SDK logging by using the .NET Core standard logging framework. After setting up the logger, ensure to pass it to the CosmosClient through the CosmosClientOptions during initialization.
In Azure Cosmos DB, where does the SDK log data reside?
The SDK logs are stored on the client machine where the Azure Cosmos DB SDK is installed and running.
Can you adjust the level of detail in Azure SDK logs?
Yes, you can adjust the level of detail in SDK logs through log level settings. Log levels from high to low are Critical, Error, Warning, Information, Verbose.
Besides logging, what mechanism can be used to track requests to Azure Cosmos DB?
Besides logging, Azure Cosmos DB also provides native support for integrating with Azure Monitor Diagnostics, which can be used to track requests, including failed ones.
Can you enable SDK logging in Java?
Yes, you can enable SDK logging in Java using SLF4J, a simple logging facade for Java which is supported by Azure Cosmos DB.
What things are typically logged by the Cosmos DB SDK when logging is enabled?
The Cosmos DB SDK typically logs operations performed against the database such as the creation, reading, updating, and deleting of Items and Containers, stored procedures execution, and any errors or exceptions that may have occurred.
Where in Python code can you enable SDK logging for Azure Cosmos DB?
You can enable SDK logging in Python code during the initiation of a CosmosClient instance. This can be achieved by setting the “enable_logging” parameter to “True”.
How can you filter what data to include in your Azure SDK logs?
The data to be included in Azure SDK logs can be filtered by setting up different log levels. Details like Information, Debug, or Error levels can be configured to control verbosity.
Is it recommended to enable SDK logging all the time, even in production environments?
No, it’s not recommended to enable SDK logging for all the time, especially in production environments, as it may affect the performance of applications. It is best used for troubleshooting, and should be turned off once the issues are resolved.
Is the data logged by Cosmos DB SDK secure?
Yes, the data logged by Azure Cosmos DB SDK does not include sensitive operational data, and any data user-related is always redacted to ensure data security.
What is the typical format of a log message in Azure Cosmos DB SDK?
The typical format of a log message in Azure Cosmos DB SDK includes timestamp, log level, activity ID, component information, and the actual message.
Can you configure SDK logging to automatically log slow requests in Azure Cosmos DB?
Yes, Azure Cosmos DB SDK has the capability to automatically log requests that exceed a certain latency threshold, which can be configured using the “SlowLogThreshold” option.
How do you disable SDK logging in Azure Cosmos DB?
To disable SDK logging, you need to set the level of the logger to ‘None’ or by setting the ‘enable_logging’ parameter to ‘False’ during the creation of the CosmosClient instance.
How can you use SDK logs to optimize performance in Cosmos DB?
SDK logs provide detailed views of all operations, their cost, and duration. By analyzing the logs, developers can identify expensive queries or operations, and optimize accordingly to improve the performance.
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