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commands/create-sample-function.md

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+---
+description: Create a sample Azure Function for testing
+---
+
+Create a sample Azure Function application for testing Datadog instrumentation.
+
+## Choose Function Type
+
+### 1. In-Process Function (.NET 6+)
+
+**Create project**:
+```bash
+func init MyFunctionApp --worker-runtime dotnet
+cd MyFunctionApp
+func new --template "HTTP trigger" --name HttpTrigger
+```
+
+**Add Datadog NuGet package**:
+```xml
+<PackageReference Include="Datadog.AzureFunctions" Version="X.X.X" />
+```
+
+**Update Program.cs** (.NET 6+ in-process):
+```csharp
+using Microsoft.Extensions.Hosting;
+
+var host = new HostBuilder()
+    .ConfigureFunctionsWorkerDefaults()
+    .Build();
+
+host.Run();
+```
+
+### 2. Isolated Worker Function (.NET 7+)
+
+**Create project**:
+```bash
+func init MyFunctionApp --worker-runtime dotnet-isolated
+cd MyFunctionApp
+func new --template "HTTP trigger" --name HttpTrigger
+```
+
+**Add Datadog NuGet package**:
+```xml
+<PackageReference Include="Datadog.AzureFunctions" Version="X.X.X" />
+```
+
+**Update Program.cs**:
+```csharp
+using Microsoft.Extensions.Hosting;
+
+var host = new HostBuilder()
+    .ConfigureFunctionsWorkerDefaults()
+    .Build();
+
+host.Run();
+```
+
+### 3. In-Process Function (.NET Framework 4.8)
+
+**Create project** (requires Visual Studio or manual setup):
+```xml
+<TargetFramework>net48</TargetFramework>
+<AzureFunctionsVersion>v4</AzureFunctionsVersion>
+```
+
+For .NET Framework, use the **Site Extension** deployment method instead of NuGet.
+
+## Configure Settings
+
+### local.settings.json
+
+```json
+{
+  "IsEncrypted": false,
+  "Values": {
+    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
+    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
+    "DD_API_KEY": "your-api-key-here",
+    "DD_SITE": "datadoghq.com",
+    "DD_ENV": "dev",
+    "DD_SERVICE": "my-function-app",
+    "DD_VERSION": "1.0.0",
+    "DD_TRACE_DEBUG": "false"
+  }
+}
+```
+
+### Add Instrumentation Code (Optional)
+
+For custom spans:
+```csharp
+using Datadog.Trace;
+
+public class HttpTrigger
+{
+    [FunctionName("HttpTrigger")]
+    public async Task<IActionResult> Run(
+        [HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequest req,
+        ILogger log)
+    {
+        using var scope = Tracer.Instance.StartActive("custom.operation");
+        scope.Span.SetTag("custom.tag", "value");
+
+        // Your function logic
+
+        return new OkObjectResult("Hello from Datadog!");
+    }
+}
+```
+
+## Test Locally
+
+**Run the function**:
+```bash
+func start
+```
+
+**Invoke the function**:
+```bash
+curl http://localhost:7071/api/HttpTrigger
+```
+
+**Verify traces**:
+- Check Datadog APM for traces
+- Review local logs for tracer messages
+- Confirm spans are created
+
+## Deploy to Azure
+
+### Using Azure CLI:
+
+**Create function app**:
+```bash
+az functionapp create \
+  --resource-group lucas.pimentel \
+  --consumption-plan-location eastus \
+  --runtime dotnet \
+  --functions-version 4 \
+  --name lucasp-test-function \
+  --storage-account <storage-account>
+```
+
+**Deploy**:
+```bash
+func azure functionapp publish lucasp-test-function
+```
+
+**Configure Datadog settings**:
+```bash
+az functionapp config appsettings set \
+  --name lucasp-test-function \
+  --resource-group lucas.pimentel \
+  --settings DD_API_KEY=<key> DD_SITE=datadoghq.com DD_ENV=test
+```
+
+## Add Different Trigger Types
+
+### Timer Trigger:
+```bash
+func new --template "Timer trigger" --name TimerTrigger
+```
+
+### Queue Trigger:
+```bash
+func new --template "Queue trigger" --name QueueTrigger
+```
+
+### Blob Trigger:
+```bash
+func new --template "Blob trigger" --name BlobTrigger
+```
+
+## Test Integration Points
+
+**HTTP calls**:
+```csharp
+using var httpClient = new HttpClient();
+var response = await httpClient.GetAsync("https://api.example.com");
+```
+
+**Database calls**:
+```csharp
+using var connection = new SqlConnection(connectionString);
+await connection.OpenAsync();
+```
+
+**Azure SDK calls**:
+```csharp
+var blobClient = new BlobClient(connectionString, containerName, blobName);
+await blobClient.DownloadAsync();
+```
+
+## Reference Sample Applications
+
+For working examples, see:
+```
+tracer/test/test-applications/azure-functions/
+```
+
+These samples demonstrate:
+- Different runtime versions
+- In-process vs isolated worker
+- Various trigger types
+- Custom instrumentation
+- Datadog configuration