Requirements

• Azure subscription

• Azure Active Directory B2C Tenant This content is ready to work with Azure Active Directory B2C, before start ensure you have your tenant ready.

  1. Create B2C Tenant
  2. Register an application and ROPC flow

• Golang SDK 1.16.2 or higher.

• VS Code with Go Extension and Azure Functions extension.

Solution

1. Function
   • Function service metadata (no code) used to initialize the Azure Function.
2. Handler
   • Handler service (golang service) used to add all the business logic to the Function.

Registered functions:

• authtoken - TimerTrigger to retrieve every 20 mins the authorization token used by graph internal API calls.
• authuser - HttpTrigger to authorize an AAD B2C user.
• createuser - HttpTrigger to create an AAD B2C user.
• getuser - HttpTrigger to obtain an AAD B2C user.
• publickeys - TimerTrigger to retrieve every day the public keys used to validate the jwt signature as part of the process validation.

References

Microsoft identity platform and OAuth 2.0 authorization code flow

Initialize your development environment

• Configure handler service settings.

  All handler service settings are in the package: identity\handler\settings.

  Configure the following settings:

  // Tenant variable
  var Tenant = "[YOUR_TENANT_NAME].onmicrosoft.com"
  
  // TenantB2CLogin variable
  var TenantB2CLogin = "[YOUR_TENANT_NAME].b2clogin.com"
  
  // PrimaryTrustFrameworkPolicy variable
  var PrimaryTrustFrameworkPolicy = "[YOUR_ROPC_FLOW_NAME]"
  
  // ClientID variable
  var ClientID = "[YOUR_APP_ID]"
  
  // ClientSecret variable
  var ClientSecret = "[YOUR_APP_ID_SECRET]"
  

• Go to the handler folder and compile golang main module.

  handler> go build main.go
  

  *Note: if you are running in Windows you will get the "main.exe" file otherwise if you are on Linux or MacOS you will get the "main" file.

• Validate the host.json configuration in Azure Functions folder.

  If your development environment is Windows then let the defaultExecutablePath attribute as as "main.exe", otherwise, change it to: "main".

    "customHandler": {
          "description": {
          "defaultExecutablePath": "main.exe",
          "workingDirectory": "",
          "arguments": []
          },
          "enableForwardingHttpRequest": true
      }
  

• Move output handler file to Azure Functions folder.

  handler> mv main.exe ..\function\main.exe -Force
  

• Go to the function folder and run the Azure Function.

  function> func start
  

• If everything runs as expected you will obtain a terminal log like this.

  Azure Functions Core Tools
  Core Tools Version:       3.0.2996 Commit hash: c54cdc36323e9543ba11fb61dd107616e9022bba
  Function Runtime Version: 3.0.14916.0
  
  
  Functions:
  
          authuser: [POST] http://localhost:7071/api/authuser
  
          createuser: [POST] http://localhost:7071/api/createuser
  
          getuser: [GET] http://localhost:7071/api/getuser
  
          authtoken: timerTrigger
  
          publickeys: timerTrigger
  
  For detailed output, run func with --verbose flag.
  [2021-03-22T20:25:44.426Z] Executing 'Functions.authtoken' (Reason='Timer fired at 2021-03-22T14:25:44.4154475-06:00', Id=3ea7822e-c57c-4b68-9e3a-86e5f4b73919)
  [2021-03-22T20:25:44.427Z] Trigger Details: UnscheduledInvocationReason: IsPastDue, OriginalSchedule: 2021-03-22T14:20:00.0000000-06:00
  [2021-03-22T20:25:45.350Z] Worker process started and initialized.
  [2021-03-22T20:25:45.728Z] Outputs not set on http response for invocationId:3ea7822e-c57c-4b68-9e3a-86e5f4b73919
  [2021-03-22T20:25:45.728Z] ReturnValue not set on http response for invocationId:3ea7822e-c57c-4b68-9e3a-86e5f4b73919
  [2021-03-22T20:25:45.739Z] Executed 'Functions.authtoken' (Succeeded, Id=3ea7822e-c57c-4b68-9e3a-86e5f4b73919, Duration=1318ms)
  [2021-03-22T20:25:45.830Z] package: structs.common - initialized  
  [2021-03-22T20:25:45.831Z] package: structs.graph - initialized   
  [2021-03-22T20:25:45.831Z] package: structs.jwt - initialized     
  [2021-03-22T20:25:45.832Z] package: structs.requests - initialized
  [2021-03-22T20:25:45.832Z] package: settings - initialized        
  [2021-03-22T20:25:45.833Z] package: graph - initialized
  [2021-03-22T20:25:45.833Z] package: jwt - initialized
  [2021-03-22T20:25:45.834Z] package: handlers.http.authuser - initialized
  [2021-03-22T20:25:45.835Z] package: handlers.http.createuser - initialized
  [2021-03-22T20:25:45.835Z] package: handlers.http.getuser - initialized
  [2021-03-22T20:25:45.836Z] package: handlers.http.testgraph - initialized
  [2021-03-22T20:25:45.837Z] package: handlers.http.updateuser - initialized
  [2021-03-22T20:25:45.837Z] package: handlers.timer.authtoken - initialized
  [2021-03-22T20:25:45.838Z] Process of obtaining authorization token started
  [2021-03-22T20:25:45.839Z] Process of obtaining authorization token finalized
  [2021-03-22T20:25:45.840Z] package: handlers.timer.publickeys - initialized
  [2021-03-22T20:25:45.840Z] Process of obtaining public keys started
  [2021-03-22T20:25:45.841Z] Process of obtaining public keys finalized
  [2021-03-22T20:25:45.842Z] package: main - initialized
  [2021-03-22T20:25:45.842Z] 2021/03/22 14:25:45 About to listen on :2267. Go to https://127.0.0.1:2267/
  [2021-03-22T20:25:45.843Z] Process of obtaining authorization token started
  [2021-03-22T20:25:45.844Z] Process of obtaining authorization token finalized
  

  At this point all the golang packages has been initialized successfully by using the Azure Function process instance.

Invoking APIs

• Function: createuser
• Method: Post
• Url: http://localhost:7071/api/createuser
• Headers:
  • Content-Type: application/json

Sample payload:
{
    "givenName": "Roberto",
    "surname": "Cervantes",
    "email": "robece@microsoft.com",
    "password": "password"
}

• Function: authuser
• Method: Post
• Url: http://localhost:7071/api/authuser
• Headers:
  • Content-Type: application/json

Sample payload:
{
	"username": "robece@microsoft.com",
	"password": "password"
}

• Function: getuser
• Method: Get
• Url: http://localhost:7071/api/getuser?username=[username]
• Headers:
  • Authorization: Bearer [authToken]

Query parameter:
- username

Azure Function deployment

There are two ways to deploy the function application, by: container or code, if container just build the source\identity\Dockerfile image, or by code just deploy Azure Function following the documentation here.