Logging .NET Azure Functions in isolated worker model

Examples of 'vanilla' App Insights logging in .NET Azure Function apps, and integrating Serilog, with both .NET 8 and 9.

• .NET 8
• .NET 8 with Serilog
• .NET 9
• .NET 9 with Serilog

Microsoft.ApplicationInsights.WorkerService 3.0.0

The v3 version of this package introduced breaking changes, including a dependency on Microsoft.ApplicationInsights, Version=3.0.0.1, which is incompatible with the Microsoft.Azure.Functions.Worker.ApplicationInsights package.

The Functions team have commented that they will not be releasing a 3.0-compatible version of Microsoft.Azure.Functions.Worker.ApplicationInsights, and instead encourage the move to OpenTelemetry monitoring.

For Functions still using Microsoft.Azure.Functions.Worker.ApplicationInsights, then stick with the latest v2 release of Microsoft.ApplicationInsights.WorkerService

Azure environment configuration

az group create --name rg-funcs-logging-australiaeast --location australiaeast

# Prepare a service principal for Login with OIDC 
az ad sp create-for-rbac --name sp-funcs-logging-australiaeast --role Contributor --scopes /subscriptions/<yoursubscription>/resourceGroups/rg-funcs-logging-australiaeast

Make a note of the appId value, as you'll enter that as the --id parameter.

https://learn.microsoft.com/entra/workload-id/workload-identity-federation-create-trust?pivots=identity-wif-apps-methods-azp&WT.mc_id=DOP-MVP-5001655#github-actions

az ad app federated-credential create --id xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx --parameters credential.json

Create credential.json

{
    "name": "Testing",
    "issuer": "https://token.actions.githubusercontent.com",
    "subject": "repo:octo-org/octo-repo:environment:Production",
    "description": "Testing",
    "audiences": [
        "api://AzureADTokenExchange"
    ]
}

Get the Azure subscription ID:

az account subscription list

and then set the following as GitHub secrets

• AZURE_CLIENT_ID the Application (client) ID
• AZURE_TENANT_ID the Directory (tenant) ID
• AZURE_SUBSCRIPTION_ID your subscription ID