Application Insights Exporter for OpenTelemetry

The Application Insights Exporter allows to read traces exported from Azure Application Insights and send it to an OpenTelemetry OTLP compatible endpoint.

Original Trace in Application Insights

Exported Trace in Dynatrace

How does it work?

The project comes with an Azure Function, bound to an EventHub from which it receives and then converts and forwards the telemetry.

Supported Application Insights telemetry types are:

• AppDependency
• AppRequests

Supported OpenTelemetry formats are:

• OTLP/HTTP binary format

Getting Started

The project contains 2 Azure Functions targeting different deployment models:

• ApplicationInsightsForwarderWorker (.NET 8 isolated worker)
• ApplicationInsightsForwarder (.NET 6 in-process)¹

Pre-Requisites

• Create or configure an Azure EventHub to which you want to forward the telemetry from your Application Insights instance.
• If your target backend doesn't support OLTP/HTTP binary format, you can use an OpenTelemetry Collector as a receiving endpoint for the Azure Function.

Sending trace telemetry to EventHub

Configure Diagnostic settings of your Application Insights instance from which you want to forward the telemtry.

• Check Dependencies and Requests in the telemetry catgories (all other categories will be ignored when processing)
• Check the Stream to an event hub and select your previously configured eventhub.

Running the forwarder locally

1. Configure local.settings.json

/* SAMPLE SETTINGS FILE FOR ISOLATED-WORKER DEPLOYMENT MODEL*/
{
  "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet-isolated",
    "EHConnection": "<YourEventHubConnectionString",
    "OTLP_ENDPOINT": "http://localhost:4318/v1/traces"
    /*,"OTLP_HEADER_AUTHORIZATION": "Api-Token XXXXX"*/
  }
}

• Replace the value of EHConnection with the connection string to read from your configured eventhub. Read more about here, how to get an Event Hub connection string. Make sure your connection string contains the configured EventHub name, provided via the additional component EntityPath which should look like this: Endpoint=sb://<NamespaceName>.servicebus.windows.net/;SharedAccessKeyName=Listen;SharedAccessKey=<KeyName>;EntityPath=<EventHubName>.
• Configure the *OTLP_ENDPOINT to point to your targeted OLTP/HTTP binary compatible endpoint. By default it's a local endpoint configured for testing.
• Optionally configure OTLP_HEADER_AUTHORIZATION. If your OTLP endpoint requires authentication, you can set the Authorization http-header with this setting.

2. Run your Function

For more details how to run an Azure Function locally see Code and test Azure Functions locally

Deploy the Function to Azure using the GitHub action

The project comes with a GitHub action to deploy the project directly to an existing Azure Function from GitHub.

Note: To be able to deploy to Azure from GitHub, make sure your Azure Function has configured the app setting WEBSITE_RUN_FROM_PACKAGE = 1. See also here

Step 1) Fork the project into your github repostiory

For more information how to fork a repository, see here: Fork a repository - GitHub-Dokumentation

Step 2) Download publishing profile from your Azure Function

To download the publishing profile of your function app:

• Select the function app's Overview page, and then select Get publish profile.

For more information how to get the publising profile, see here: Get a publish profile from Azure App Service - Microsoft Learn

Step 3) Add the GitHub secret and variables

• Go to Settings.
• Select Secrets and variables > Actions.
• Select New repository secret.
• Add a new secret with the name AZURE_FUNCTIONAPP_PUBLISH_PROFILE and the value set to the contents of the publishing profile file.
• Select Add secret.

GitHub can now authenticate to your function app in Azure.

• Select New repository variable.
• Add a new variable with the name AZURE_FUNCTIONAPP_NAME and the value set to the name of your Azure Function.
• Select Add variable.

The GitHub action now has all necessary details to deploy the function code to your Azure Function.

Step 4) Trigger the GitHub action to deploy to Azure

The workflow is configured to be manually triggered.

• In GitHub, go to your forked repository.
• Go to Actions.
• Select the workflow Deploy ApplicationInsightsForwarderWorker or Deploy ApplicationInsightsForwarder.
• Select Run workflow

[Optional] Run an OpenTelemetry Collector

The project contains a collector config otel_collector_config.yaml, configured with a pipeline for an OTLP/HTTP format requiring an authorization token. It allows to pass the receiving OTLP endpiont and an authorization token via environment variables.

receivers:
  otlp:
    protocols:
      http:
exporters:
  otlphttp:
    endpoint: "${OTLPHTTP_ENDPOINT}"
    headers: {"Authorization": "Api-Token ${API_TOKEN}"}
service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: []
      exporters: [otlphttp]

Now run the standard OpenTelemetry collector image from Docker-Hub otel/opentelemetry-collector-contrib, dynamically passing over necessary configuration.

Windows

docker run -p 4318:4318  -e OTLPHTTP_ENDPOINT="<Your-receiving-OTLP-endpoint>" -e API_TOKEN="<Your-api-token>" -v %cd%/otel_collector_config.yaml:/etc/otelcol-contrib/config.yaml otel/opentelemetry-collector-contrib

Linux

docker run -p 4318:4318  -e OTLPHTTP_ENDPOINT="<Your-receiving-OTLP-endpoint>" -e API_TOKEN="<Your-api-token>" -v $(pwd)/otel_collector_config.yaml:/etc/otelcol-contrib/config.yaml otel/opentelemetry-collector-contrib

Note: Replace <Your-receiving-OTLP-endpoint> and <Your-api-token> with the values matching your trace backend's configuration

Release Notes

• v0.1.0 - Initial release supporting AppDependency, AppRequests mapped and forwarded to OTLP/HTTP JSON
• v0.9.0 - Swichting from OTLP/HTTP json format to OTLP/HTTP binary format.
• v1.0.0 - Updating attribute mapping to better fit OpenTelemetry semantic conventions. Added a new forwarder function based on .NET 8 isolated worker model.

Contribute

This is an open source project, and we gladly accept new contributions and contributors.

License

Licensed under Apache 2.0 license. See LICENSE for details.

Footnotes

1. It is recommended to use the ApplicationInsightsForwarderWorker function using the isolated worker model as recommended by Microsoft here. ↩