This example demonstrates how to instrument an serverless Azure container app written in .NET using OpenTelemetry, and then export the data to Splunk Observability Cloud. We'll use .NET 8 for this example.

The following tools are required to deploy .NET container apps:

• An Azure account with permissions to create and execute Azure container apps
• Azure CLI
• An OpenTelemetry collector that's accessible to the Azure function

For this example, we deployed the Splunk Distribution of the OpenTelemetry Collector onto a virtual machine in Azure using Gateway mode, and ensured it's accessible to our Azure function.

Please refer to Install the Collector using packages and deployment tools for collector installation instructions.

For this example, we'll use the Hello World .NET application. The Kubernetes example explains how we created the Docker image that we'll be using.

Execute the following steps to login with the Azure CLI, ensure it has the container app extension, and register the Microsoft.App and Microsoft.OperationalInsights namespaces, as described in Quickstart: Deploy your first container app with containerapp up:

az login
az upgrade
az extension add --name containerapp --upgrade
az provider register --namespace Microsoft.App
az provider register --namespace Microsoft.OperationalInsights

Execute the following command to deploy the Azure container app, substituting the IP address or domain name for your OpenTelemetry collector:

az containerapp up \
  --name containerapps-dotnet-example \
  --resource-group containerapps-dotnet \
  --location westus \
  --environment 'containerapps-dotnet' \
  --image ghcr.io/splunk/sampledotnetapp:1.0 \
  --target-port 8080 \
  --env-vars OTEL_SERVICE_NAME="containerapps-dotnet-example" OTEL_RESOURCE_ATTRIBUTES="deployment.environment=test,service.version=1.0" OTEL_EXPORTER_OTLP_ENDPOINT="http://<collector IP>:4318" OTEL_LOGS_EXPORTER="none" \
  --ingress external \
  --query properties.configuration.ingress.fqdn

Copy the function URL from the output of the command above, which should be something like the following:

Browse to your container app at: http://<container app name>.livelydune-678049b5.westus.azurecontainerapps.io 

Then point your browser to that URL, it should return:

Hello, World! 

After a minute or so, you should start to see traces for the container app appearing in Splunk Observability Cloud:

Metrics are collected by the Splunk Distribution of OpenTelemetry .NET automatically.
For example, the process.memory.virtual metric shows us the size of the heap used by each generation in the CLR:

Logs generated by an Azure function get sent to Application Insights. Various methods exist for ingesting logs into Splunk platform from Application Insights, such as the Splunk Add-on for Microsoft Cloud Services.

Once the logs are in Splunk platform, they can be made available to Splunk Observability Cloud using Log Observer Connect.

In the following example, we can see that the trace context was injected successfully into the logs using the custom logging changes described above:

{
  "event_id": 0,
  "log_level": "information",
  "category": "HelloWorldController",
  "message": "Processing a request...",
  "timestamp": "2025-03-25T18:20:14.5916362Z",
  "service.name": "containerapps-dotnet-example",
  "severity": "INFO",
  "span_id": "b938c67d8e4e115f",
  "trace_id": "4f1d6d48a04a5e6ea9d029e955bccdc3",
  "parent_id": "0000000000000000",
  "tag_server.address": "containerapps-dotnet-example.livelydune-678049b5.westus.azurecontainerapps.io",
  "tag_http.request.method": "GET",
  "tag_url.scheme": "http",
  "tag_url.path": "/",
  "tag_network.protocol.version": "1.1",
  "tag_user_agent.original": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36",
  "ConnectionId": "0HNBBP6FTP38O",
  "RequestId": "0HNBBP6FTP38O:00000003",
  "RequestPath": "/",
  "ActionId": "4528c4b1-cd44-4be3-b9bf-687edf297c1e",
  "ActionName": "HelloWorldController.Index (HelloWorld)"
}

This will ensure full correlation between traces generated by the OpenTelemetry instrumentation with metrics and logs.