add documentation (#6)

README.md

@@ -1 +1,77 @@
-# confluent-kafka-extensions-opentelemetry
+# Confluent.Kafka.Extensions.OpenTelemetry
+
+![GitHub Actions Badge](https://github.com/vhatsura/confluent-kafka-extensions-opentelemetry/actions/workflows/continuous.integration.yml/badge.svg)
+[![NuGet Badge](https://buildstats.info/nuget/Confluent.Kafka.Extensions.OpenTelemetry)](https://www.nuget.org/packages/Confluent.Kafka.Extensions.OpenTelemetry/)
+
+The `Confluent.Kafka.Extensions.OpenTelemetry` package enables collection of instrumentation data of the `Confluent.Kafka` library.
+The actual instrumentation of the `Confluent.Kafka` library should be configured using
+[Confluent.Kafka.Extensions.Diagnostics](https://github.com/vhatsura/confluent-kafka-extensions-diagnostics).
+
+## Installation
+
+```powershell
+Install-Package Confluent.Kafka.Extensions.OpenTelemetry
+```
+
+## Usage
+
+### Confluent.Kafka configuration
+
+As `Confluent.Kafka` does not expose any instrumentation data, additional, configuration is required.
+Full documentation is available at [Confluent.Kafka.Extensions.Diagnostics docs](https://github.com/vhatsura/confluent-kafka-extensions-diagnostics#usage).
+There is also an [example](./examples/WebExample) on how to use the package in real world application.
+
+#### Producer
+
+```csharp
+using Confluent.Kafka;
+using Confluent.Kafka.Extensions.Diagnostics;
+
+
+using var producer =
+    new ProducerBuilder<Null, string>(new ProducerConfig(new ClientConfig { BootstrapServers = "localhost:9092" }))
+        .SetKeySerializer(Serializers.Null)
+        .SetValueSerializer(Serializers.Utf8)
+        .BuildWithInstrumentation();
+
+await producer.ProduceAsync("topic", new Message<Null, string> { Value = "Hello World!" });
+```
+
+#### Consumer
+
+```csharp
+using Confluent.Kafka;
+using Confluent.Kafka.Extensions.Diagnostics;
+
+using var consumer = new ConsumerBuilder<Ignore, string>(
+        new ConsumerConfig(new ClientConfig { BootstrapServers = "localhost:9092" })
+        {
+            GroupId = "group", AutoOffsetReset = AutoOffsetReset.Earliest
+        })
+    .SetValueDeserializer(Deserializers.Utf8)
+    .Build();
+
+consumer.Subscribe("topic");
+
+consumer.ConsumeWithInstrumentation((result) =>
+{
+    Console.WriteLine(result.Message.Value);
+});
+```
+
+### OpenTelemetry configuration
+
+```csharp
+using Confluent.Kafka.Extensions.OpenTelemetry;
+using OpenTelemetry.Resources;
+using OpenTelemetry.Trace;
+
+builder.Services.AddOpenTelemetryTracing(traceBuilder =>
+{
+    traceBuilder
+        .AddInMemoryExporter()
+        .AddHttpClientInstrumentation()
+        .AddAspNetCoreInstrumentation()
+        .AddConfluentKafkaInstrumentation();  // <-- Add Confluent.Kafka OpenTelemetry support
+});
+```