Azure Deploy Example - C# .NET

Today we’ll deploy a tiny C# .NET function to Azure Functions on the Linux Consumption plan. It’s a single HTTP endpoint that returns “Hello world.”

Architecture

Dependencies

• Azure Functions Core Tools v4
• Azure CLI
• (New users) Create free Azure account or credits
• Dotnet SDK v8

If you use VSCode, you may want following extensions:

• C# (ms-dotnettools.csharp) or C# Dev Kit (ms-dotnettools.csdevkit)
• Azure Functions (ms-azuretools.vscode-azurefunctions)
• For Azure sign-in: Azure Account (ms-vscode.azure-account)

Login to Azure and select subscription

We need to login to Azure. Use the default subscription that was created when free account was created.

az login
az account list -o table
az account set --subscription "<Your-Subscription-Name-or-ID>"

Register namespaces

We need a couple namespaces enabled for the application, so enable them if not already. If state is “registering”, wait a couple minutes and run show command again.

az provider show --namespace Microsoft.Storage --query "registrationState"
az provider show --namespace Microsoft.Web    --query "registrationState"
az provider register --namespace Microsoft.Storage
az provider register --namespace Microsoft.Web

Create resource group

Resource group contains all the resources for this project. Choose the location from given list, we use westeurope as an example.

az account list-locations --query "[].name" -o tsv
az group create \
  -n azure-deploy-example \
  -l westeurope

Create storage account

Functions requires a general-purpose storage account for triggers, logs, and state.

Use Standard_LRS (lowest cost). Storage isn’t “free”, but with small usage and free credits it’s typically zero cost while learning. Naming rules: 3–24 chars, lowercase letters & numbers only, globally unique. So in case the name is taken, choose some other name.

az storage account create \
  -n azuredeployecxzxghr0m \
  -g azure-deploy-example \
  -l westeurope \
  --sku Standard_LRS

Create function app

Next we create function application that holds our functions. Application name must be globally unique (becomes <name>.azurewebsites.net).

az functionapp create \
  -n azure-deploy-example-dotnet-ecxzxghr0m \
  -g azure-deploy-example \
  --consumption-plan-location westeurope \
  --runtime dotnet-isolated \
  --runtime-version 8 \
  --functions-version 4 \
  --os-type linux \
  --storage-account azuredeployecxzxghr0m

Prepare the app

The application is very basic, mostly whatever is coming from scaffold. Application sources are here.

Scaffold the project

Create repository files with func cli tool. We use isolated dotnet, so the process dependencies does not get mixed up.

mkdir dotnet-func && cd dotnet-func
func init . --dotnet-isolated

Create function

Save file to Functions/test.ts

using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;

namespace Company.Function;

public class Test
{
    [Function("Test")]
    public async Task<HttpResponseData> Run(
        [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "test")]
        HttpRequestData req,
        FunctionContext ctx)
    {
        var res = req.CreateResponse(HttpStatusCode.OK);
        await res.WriteAsJsonAsync(new { message = "Hello world from dotnet" });
        return res;
    }
}

Note: we use async + WriteAsJsonAsync to avoid the “Synchronous operations are disallowed” error

Run locally

Build and run application, and then we can test it with curl, browser or any other similar tool.

dotnet build
func start

# in another terminal window
curl http://localhost:7071/api/test

Publish

This will publish app to production.

dotnet build
func azure functionapp publish azure-deploy-example-ecxzxghr0m

# test in the cloud
curl https://azure-deploy-example-ecxzxghr0m.azurewebsites.net/api/test

Recap

We created a Function App, added a C# .NET HTTP function, tested locally, and published to Azure.