Azure SDK Release (February 2020) – Logging with the Azure SDKs
Adrian
Welcome to the February release of the Azure SDK. We have updated the following libraries:
- Cosmos DB (JavaScript only).
- Event Hubs (Java and JavaScript).
- Key Vault (Python only).
- Storage (Blobs, Files, and Queues).
These are ready to use in your production applications. You can find details of all released libraries on our releases page.
New preview releases:
- Cosmos (Java only).
- Key Vault Keys (Java only).
- Storage Blob Cryptography.
- Storage Data Lake Files.
- Text Analytics.
We believe these are ready for your use, but not yet ready for production. Between now and the GA release, these libraries may undergo API changes. We’d love your feedback! If you use these libraries and like what you see, or you want to see changes, let us know in the GitHub issues for the appropriate language..
Logging with the Azure SDKs
One of the main advantages of the new Azure SDK is that common developer concerns are treated the same, irrespective of which client library you are using. In this issue, we will tackle logging and show you how to enable logging on each platform.
.NET libraries
All .NET client libraries emit events to ETW (Event Tracing for Windows) via the
EventSource class. This system has been a part of the .NET framework for a long time. Event sources allow you to use structured logging in your application code with a minimal performance overhead.
Although you can use out-of-process tools (such as PerfView or dotnet trace), a core tenet of our libraries includes the ability to easily send logs to the console. When developing your app, you should be able to view the logs in real time without much overhead. You can accomplish this with a one-liner at the top of your application:
using AzureEventSourceListener listener = AzureEventSourceListener.CreateConsoleLogger();
Java libraries
The Java client libraries all use SLF4J under the covers for logging. There are many mechanisms for configuring SLF4J to get just the right logging for your application. By default, there is no SLF4J implementation in the client library. Today, we will show the easiest implementation – the simple logger. Download and add slf4j-simple 1.7.28.jar to your classpath (ensuring you do not have another SLF4J library in your app). Set the
AZURE_LOG_LEVEL environment variable to “verbose”. For example, in bash:
export AZURE_LOG_LEVEL="verbose"
Or, in PowerShell:
$env:AZURE_LOG_LEVEL="verbose"
Then run your application as normal. The logs will be emitted on the console. For more information on the Java logging system, refer to our wiki.
JavaScript and TypeScript libraries
There are two easy ways to enable logging for your Node applications. You can set the
AZURE_LOG_LEVEL to “verbose”. In this case, the logs will be output to stderr (for Node applications) or the console (for browser applications). For example, in bash:
export AZURE_LOG_LEVEL="verbose"
Or, in PowerShell:
$env:AZURE_LOG_LEVEL="verbose"
If you want to do the same thing in code, you can use the
@azure/logger module:
import { setLogLevel } from "@azure/logger"; setLogLevel("verbose");
This allows you to be more dynamic in your logging. For example, you might want to enable logging on a single client library, or replace the logger with your own implementation. For more information, check out the logger library.
Python libraries
Python uses the standard logging module. This makes it really easy to configure just like you would any other Python library:
import logging logging.basicConfig() # Enable DEBUG logging for all azure libraries azure_root_logger = logging.getLogger('azure') azure_root_logger.setLevel(logging.DEBUG)
You can see more configuration examples in the logging cookbook.
As you can see, the same logging features are provided in each language, but how each language accomplishes them is idiomatic to the language. How you work with these features should feel very natural in your language of choice.
If it doesn’t, let us:
Finally, please keep up to date with all the news about the Azure developer experience programs and let us know how we are doing by following @azuresdk on Twitter.