Azure FUnctions: Sample Rest App

Prerequisites:

• An Azure account with an active subscription. Create an account for free
• Install Visual Studio Code
• Install Azure Functions extension for Visual Studio Code
• Install Azure Functions Core Tools version 3.x. Use the func --version command to check that it is correctly installed

App Endpoints Exposed:

Method	Endpoint	Description
GET	/tasks	List all tasks
GET	/tasks/{id}	List details of specific task
POST	/tasks	Create new task

Schema for Task:

{
	"id": "7b2da5e4-0ef9-4339-a8df-ecf2116575bc",
	"task": "Sample todo task"
}

How to create your own functions app project:

1. Create a new directory and enter it. Create a new function app using the following command:

   func init --worker-runtime custom --docker
   

2. Now create a new function from a template using command:

   func new --name <your-app-name-here> --template "HTTP trigger"
   

3. Download or build the binary for your HTTP Trigger app and copy into the directory you created in step 1 and make sure it's executable. If not use the following command:

   chmod +x <binary-file-name-here>
   

4. Add the following script into your project folder with name start.sh and also make it executable:

   #!/usr/bin/env sh
   echo "Starting function..."
   PORT=${FUNCTIONS_CUSTOMHANDLER_PORT} ./TasksRestServer-linux_amd64
   

   chmod +x start.sh
   

5. Edit your function.json to update the default app prefix from api to your prefix. For example I'll change it to hello-world

   {
   "bindings": [
       {
       "authLevel": "anonymous",
       "type": "httpTrigger",
       "direction": "in",
       "name": "req",
       "methods": ["get", "post"],
       "route": "hello-world"
       },
       {
       "type": "http",
       "direction": "out",
       "name": "res"
       }
   ]
   }
   

6. Edit your host.json to look like this:

   {
   "version": "2.0",
   "logging": {
       "applicationInsights": {
       "samplingSettings": {
           "isEnabled": true,
           "excludedTypes": "Request"
       }
       }
   },
   "extensionBundle": {
       "id": "Microsoft.Azure.Functions.ExtensionBundle",
       "version": "[2.*, 3.0.0)"
   },
   "customHandler": {
       "description": {
       "defaultExecutablePath": "start.sh",
       "workingDirectory": "",
       "arguments": []
       },
       "enableForwardingHttpRequest": true
   },
   "extensions": {
       "http": {
       "routePrefix": ""
       }
   }
   }
   

7. Finally edit your Dockerfile to look like this:

   # To enable ssh & remote debugging on app service change the base image to the one below
   FROM mcr.microsoft.com/azure-functions/dotnet:3.0-appservice 
   ENV AzureWebJobsScriptRoot=/home/site/wwwroot \
       AzureFunctionsJobHost__Logging__Console__IsEnabled=true
   COPY . /home/site/wwwroot
   

8. You can now test your app locally by running the following command:

   func start
   

   Check if your app works by visiting the URL:

   http://localhost:7071/tasks
   

9. Now follow the instructions here to publish your app to azure: Publish the project to Azure