Added serilog docs

en/studio/solution-templates/microservice/index.md

@@ -20,7 +20,7 @@ ABP Studio provides pre-architected and production-ready templates to jump start
 * Built-In Features
   * [Authentication](authentication.md)
   * [Database configurations](database-configurations.md)
-  * [Logging (with Serilog)](logging.md)
+  * [Logging (with Serilog and Elasticsearch)](logging.md)
   * Monitoring (with Prometheus and Grafana)
   * Swagger integration
   * Permission management

en/studio/solution-templates/microservice/logging.md

@@ -1,3 +1,26 @@
 # Microservice Solution: Logging
 
-TODO
+The ABP Studio [microservice solution template](index.md) is fully configured for [logging](https://docs.abp.io/en/abp/latest/Logging). All the services, applications and gateways are configured to use the [Serilog](https://serilog.net/) library for structured logging. They are configured in a common way for logging. This document explains that common logging structure.
+
+## The Serilog Sinks
+
+The Serilog library is configured so it writes the logs to the following targets (a.k.a. [sinks](https://github.com/serilog/serilog/wiki/Provided-Sinks)) in parallel:
+
+* **[Console](https://github.com/serilog/serilog-sinks-console)**: Logs are written to the standard output of the executing application. Logging to console is useful when you want to see logs easily while it is running in a container.
+* **[File](https://github.com/serilog/serilog-sinks-file)**: Logs are written to a file named `logs.txt` located under the `Logs` folder of the executing application. File logging is useful when you run the application on your local computer. You can check logs easily when you have a trouble. This sinks is only configured for DEBUG mode. It won't be available in your production environment (you can change the behavior in your `Program.cs` file).
+* **[ElasticSearch](https://github.com/serilog-contrib/serilog-sinks-elasticsearch)**: Logs are sent to an [Elasticsearch](https://www.elastic.co/) server. Elasticsearch is especially useful when you want to search and trace the logs. This microservice solution is also includes a Kibana container configuration, so you can visualize and search your logs easily. See your `appsettings.json` file for the Elasticsearch configuration.
+* **ABP Studio**: This is a Sink provided by ABP Studio. It sends all logs to ABP Studio, so you can easily monitor your logs in real-time on your ABP Studio Application Monitoring panel.
+
+The solution can work with [any sink](https://github.com/serilog/serilog/wiki/Provided-Sinks) supported by Serilog. You can add more sinks, remove pre-installed sinks or fine tune their configuration for your solution.
+
+## Program.cs
+
+The `Program.cs` file is the main point that configures the logging system. It is done here, because we want to initialize and start the logging in the very beginning of the application.
+
+## Additional Information
+
+You can easily understand the Serilog configuration when you check your `Program.cs`. However, there are a few things worth mentioning here:
+
+* We are adding an `Application` property to every log record, so you can filter logs by the application name. It is done in the `Program.cs` file with the `.Enrich.WithProperty("Application", applicationName)` line. The `applicationName` value is taken from [the `IApplicationInfoAccessor` service](https://docs.abp.io/en/abp/8.0/Application-Startup#the-applicationname-option) of ABP Framework. By default, it is the name of the entrance assembly (that contains the `Program.cs` file) of the application.
+* We are using ABP Serilog Enrichers in the module class of the application. It is done by the `app.UseAbpSerilogEnrichers();` line in the `OnApplicationInitialization` method of your module class. That ASP.NET Core middleware adds current [tenant](https://docs.abp.io/en/abp/latest/Multi-Tenancy), [user](https://docs.abp.io/en/abp/latest/CurrentUser), client and correlation id information to the log records.
+