1. Logging
In ASP.Net Core 1.1

2. Logging
Your program (web app) will run on a server, 24x7, forever and ever
If something goes wrong you want to get useful info about what happened
You may not be able to attach the debugger to the web app
You may not be able to reproduce the problem
Logging:
Saving messages for later reference, in order to help you figure out what your program is doing wrong / underperforming / how that hacker broke into your system / etc

3. Tutorial We’ll be walking through:

4. Providers
“A logging provider takes some action on logged data, such as display it on the console or store it in Azure blob storage. ”
Examples of providers:
Print it to the console (just like Console.WriteLine)
Save it to a file
Save it to a database
Save it to Azure (aka “save it to a file/database in the cloud”)
Built-in providers:
logging-providers
You can also use 3rd party providers (your own, or written by someone else)

5. Providers
Let’s add in the Console & Debugger providers, as per that first step in the turorial

6. Adding Items To The Log(s)
<Let’s look a the sample code in “How to create logs”>
Let’s go through “Sample logging output”

7. Adding Items To The Log(s)
Categories
So you know where the message is coming from
Log Level
You can specify how important it is to see the message
You can then tell the logger what level (and above) you want to see
This way you can put a ton of messages in at the ‘Debug’ (lowest) level, set the level to display higher for day-to-day use, and only see critical messages normally. Once you know there’s a bug you can change the log level to be ‘debug’ to get detailed information (for debugging purposes)
This is covered in the “Log filtering” section

8. Let’s Add Logging To Your App