docs: integrated logging documentation (#900)

Add documentation page about logging, open telemetry and azure logging.

Author: kimpenhaus

docs/docs/operator/deployment.mdx

@@ -1,7 +1,7 @@
 ---
 title: Deployment
 description: Deploying your KubeOps Operator
-sidebar_position: 6
+sidebar_position: 7
 ---
 
 # Deployment

docs/docs/operator/logging.mdx

@@ -0,0 +1,177 @@
+---
+title: Logging
+description: Logging, Tracing, and OpenTelemetry
+sidebar_position: 6
+---
+
+# Logging, Tracing, and OpenTelemetry
+
+## 1. Logging with `ILogger` and Scopes
+
+This project uses Microsoft's [`ILogger`](https://learn.microsoft.com/en-us/dotnet/core/extensions/logging) interface for logging. It provides a standardized and extensible way to capture events within the application.
+
+Using *scopes* enables hierarchical organization of log messages and allows contextual information to be attached to each entry.
+
+### 1.1 ILogger Basics
+
+The `ILogger` interface is part of [`Microsoft.Extensions.Logging`](https://www.nuget.org/packages/Microsoft.Extensions.Logging) and provides methods to log messages at various severity levels (e.g., `Information`, `Warning`, `Error`).
+
+Logging can be enabled using either `WebApplication.CreateBuilder`, `Host.CreateDefaultBuilder`, or the `AddLogging` extension method on the `IServiceCollection`.
+
+You can log from your code by injecting `ILogger<MyEntityController>` (or a similar type) into your component.
+
+### 1.2 Using Scopes
+
+Scopes define a logical boundary in which all log entries are automatically enriched with contextual metadata. This is especially useful for correlating logs related to a specific request or operation.
+
+By default, the [ResourceWatcher](https://github.com/buehler/dotnet-operator-sdk/blob/main/src/KubeOps.Operator/Watcher/ResourceWatcher%7BTEntity%7D.cs) starts a new scope for every watch event it processes. Each scope includes:
+
+- `EventType`: Type of the received watch event (`Added`, `Modified`, `Deleted`, `Error`, `Bookmark`)
+- `Kind`: Custom Resource Definition (CRD) kind
+- `Namespace`: CRD namespace
+- `Name`: CRD name
+- `ResourceVersion`: CRD resource version
+
+You can create additional scopes in your code using `logger.BeginScope(state)`, where `state` can be either a string or a custom object.
+
+To include scopes in the logging output, they must be explicitly enabled either via configuration or code:
+
+**`appsettings.json`:**
+
+```json
+"Logging": {
+  "Console": {
+    "FormatterName": "Simple",
+    "FormatterOptions": {
+      "IncludeScopes": true
+    }
+  },
+  "LogLevel": {
+    "Default": "Information",
+    "KubeOps": "Trace"
+  }
+}
+```
+
+**Programmatic configuration:**
+
+```csharp
+builder
+    .ConfigureLogging((hostBuilderContext, loggingBuilder) =>
+    {
+        loggingBuilder
+            .AddSimpleConsole(options => options.IncludeScopes = true);
+    });
+```
+
+:::tip
+To enable scopes with OpenTelemetry, configure it as follows:
+
+```json
+"OpenTelemetry": {
+  "IncludeScopes": true,
+  "ParseStateValues": true,
+  "IncludeFormattedMessage": true
+}
+```
+
+The scope state must be an `IReadOnlyDictionary<string, object?>` to ensure correct serialization and inclusion in log entries.
+:::
+
+## 2. Tracing with `System.Diagnostics` and `ActivitySource`
+
+For [distributed tracing](https://learn.microsoft.com/en-us/dotnet/core/diagnostics/distributed-tracing-concepts), this project uses `System.Diagnostics` in combination with `ActivitySource`.
+Activities can be started using `ActivitySource.StartActivity`.
+
+The operator registers an `ActivitySource` instance with the operator name in the dependency injection (DI) container. To use a custom `ActivitySource`, simply register your own, the DI will provide the last registered instance when requested.
+
+:::tip
+You can configure the operator name (and thus the `ActivitySource` name) via `OperatorSettings`:
+
+```csharp
+const string OperatorName = "my-operator";
+
+builder
+    .Services
+    .AddKubernetesOperator(settings => settings.Name = OperatorName);
+```
+
+If you're using OpenTelemetry, tracing must be explicitly configured in code. Make sure to add the same source name used when creating the `ActivitySource`.
+
+Also, create a `ResourceBuilder` to name your service properly in trace output:
+
+```csharp
+builder.Services
+    .AddOpenTelemetry()
+    .WithTracing(tracerProviderBuilder =>
+        tracerProviderBuilder
+            .SetResourceBuilder(
+                ResourceBuilder.CreateDefault()
+                    .AddService(serviceName: OperatorName, serviceVersion: "1.0.0"))
+            .AddSource(OperatorName));
+```
+:::
+
+## 3. OpenTelemetry Configuration for Azure Logging
+
+To use OpenTelemetry with Azure, it is recommended to adopt the [Azure Monitor OpenTelemetry Distro](https://learn.microsoft.com/en-us/azure/azure-monitor/app/opentelemetry-enable).
+You can enable it via code:
+
+```csharp
+builder.Services
+    .AddOpenTelemetry()
+    .UseAzureMonitor();
+```
+
+### 3.2 Full Example Configuration in `Program.cs` (or `Startup.cs`)
+
+A complete setup with logging, tracing, and OpenTelemetry might look like this:
+
+**`appsettings.json`:**
+
+```json
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "KubeOps": "Trace"
+    },
+    "Console": {
+      "FormatterName": "Simple",
+      "FormatterOptions": {
+        "IncludeScopes": true,
+        "SingleLine": true
+      }
+    },
+    "OpenTelemetry": {
+      "IncludeScopes": true,
+      "ParseStateValues": true,
+      "IncludeFormattedMessage": true
+    }
+  }
+}
+```
+
+**`Program.cs`:**
+
+```csharp
+const string OperatorName = "my-platform-operator";
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder
+    .Services
+    .AddKubernetesOperator(settings => settings.Name = OperatorName)
+    .RegisterComponents();
+
+builder
+    .Services
+    .AddOpenTelemetry()
+    .WithTracing(tracerProviderBuilder =>
+        tracerProviderBuilder
+            .SetResourceBuilder(
+                ResourceBuilder.CreateDefault()
+                    .AddService(serviceName: OperatorName, serviceVersion: "1.0.0"))
+            .AddSource(OperatorName))
+    .UseAzureMonitor();
+```

docs/docs/operator/testing/_category_.json

@@ -1,5 +1,5 @@
 {
-  "position": 7,
+  "position": 8,
   "label": "Testing",
   "collapsible": true,
   "collapsed": true