How to write to Windows Azure Website’s application log and more

We struggled with Windows Azure website because we couldn’t write logs. Using Log4Net to write to log file as we used to do, does not work for Azure Website because of the limited file permission. We had to resort to email notification or Virtual Machine when we needed to debug Azure Websites, which was a big headache!

Fortunately, it is all over now. To write to the Application Log of Azure Website, just use System.Diagnostics.Trace name space and use method like TraceInformation, TraceError, TraceWarning to record different levels of log!


Trace.Wrietline("Log Verbose level log");

Trace.TraceInformation ("Log Information level log");

Trace.TraceWarning("Log Warning level log");

Trace.TraceError("Log Error level log");

Then just turn on the Application Logging and select a logging level for that Azure Website.

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With this feature, it becomes much easier to troubleshoot Azure websites. Even better, Microsoft provides this streaming log function from which you can view application logs in REAL-TIME! (New Azure portal only)

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Furthermore, here is something developers will definitely like – this streaming log is also available in Visual Studio, and you can filter the result using Regular Expression! (Latest version Azure SDK is required)

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Since file logging is supposed to be turned off automatically after 12 hours, if you also want to log into a table storage, not a problem. You can set up a Azure Storage to hold the log.

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Click View settings of the Azure Website in Visual Studio.  In the Log tab, there  will  be a nice table view of the log. I do notice that it uses a lot of memory of the Azure Website. Just something to consider.

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That’s what I know about logging to Azure Websites. Hopefully it is helpful. We use Azure on most of our web applications and I think it is just getting better everyday. Now with the ability to write application log for Azure Website, it just meets all of our needs, but there is still a huge set of exciting features we haven’t used. I look forward to exploring those someday!

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