SMART on FHIR overview

Step 1: Set admin consent for your client application

To use SMART on FHIR, you must first authenticate and authorize the app. The first time you use SMART on FHIR, you also must get administrative consent to let the app access your FHIR resources.

If you don't have an ownership role in the app, contact the app owner and ask them to grant admin consent for you in the app.

If you do have administrative privileges, complete the following steps to grant admin consent to yourself directly. (You also can grant admin consent to yourself later when you're prompted in the app.) You can complete the same steps to add other users as owners, so they can view and edit this app registration.

To add yourself or another user as owner of an app:

1. In the Azure portal, go to Microsoft Entra ID.
2. In the left menu, select App Registration.
3. Search for the app registration you created, and then select it.
4. In the left menu, under Manage, select Owners.
5. Select Add owners, and then add yourself or the user you want to have admin consent.
6. Select Save

Step 2: Enable the SMART on FHIR proxy

SMART on FHIR requires that Audience has an identifier URI equal to the URI of the FHIR service. The standard configuration of the Azure API for FHIR uses an Audience value of https://azurehealthcareapis.com. However, you can also set a value matching the specific URL of your FHIR service (for example https://MYFHIRAPI.azurehealthcareapis.com). This is required when working with the SMART on FHIR proxy.

To enable the SMART on FHIR proxy in the Authentication settings for your Azure API for FHIR instance, select the SMART on FHIR proxy check box:

The SMART on FHIR proxy acts as an intermediary between the SMART on FHIR app and Microsoft Entra ID. The authentication reply (the authentication code) must go to the SMART on FHIR proxy instead of the app itself. The proxy then forwards the reply to the app.

Because of this two-step relay of the authentication code, you need to set the reply URL (callback) for your Microsoft Entra client application to a URL that is a combination of the reply URL for the SMART on FHIR proxy and the reply URL for the SMART on FHIR app. The combined reply URL takes this form:

https://MYFHIRAPI.azurehealthcareapis.com/AadSmartOnFhirProxy/callback/aHR0cHM6Ly9sb2NhbGhvc3Q6NTAwMS9zYW1wbGVhcHAvaW5kZXguaHRtbA

In that reply, aHR0cHM6Ly9sb2NhbGhvc3Q6NTAwMS9zYW1wbGVhcHAvaW5kZXguaHRtbA is a URL-safe, base64-encoded version of the reply URL for the SMART on FHIR app. For the SMART on FHIR app launcher, when the app is running locally, the reply URL is https://localhost:5001/sampleapp/index.html.

You can generate the combined reply URL by using a script like this:

$replyUrl = "https://localhost:5001/sampleapp/index.html"
$fhirServerUrl = "https://MYFHIRAPI.azurewebsites.net"
$bytes = [System.Text.Encoding]::UTF8.GetBytes($ReplyUrl)
$encodedText = [Convert]::ToBase64String($bytes)
$encodedText = $encodedText.TrimEnd('=');
$encodedText = $encodedText.Replace('/','_');
$encodedText = $encodedText.Replace('+','-');

$newReplyUrl = $FhirServerUrl.TrimEnd('/') + "/AadSmartOnFhirProxy/callback/" + $encodedText

Add the reply URL to the public client application that you created earlier for Microsoft Entra ID:

Step 3: Get a test patient

To test the Azure API for FHIR and the SMART on FHIR proxy, you'll need to have at least one patient in the database. If you've not interacted with the API yet, and you don't have data in the database, see Access the FHIR service using Postman to load a patient. Make a note of the ID of a specific patient.

Step 4: Download the SMART on FHIR app launcher

The open-source FHIR Server for Azure repository includes a simple SMART on FHIR app launcher and a sample SMART on FHIR app. In this tutorial, use this SMART on FHIR launcher locally to test the setup.

You can clone the GitHub repository and go to the application by using these commands:

git clone https://github.com/Microsoft/fhir-server
cd fhir-server/samples/apps/SmartLauncher

The application needs a few configuration settings, which you can set in appsettings.json:

{
    "FhirServerUrl": "https://MYFHIRAPI.azurehealthcareapis.com",
    "ClientId": "APP-ID",
    "DefaultSmartAppUrl": "/sampleapp/launch.html"
}

We recommend that you use the dotnet user-secrets feature:

dotnet user-secrets set FhirServerUrl https://MYFHIRAPI.azurehealthcareapis.com
dotnet user-secrets set ClientId <APP-ID>

Use this command to run the application:

dotnet run

Step 5: Test the SMART on FHIR proxy

After you start the SMART on FHIR app launcher, you can point your browser to https://localhost:5001, where you should see the following screen:

When you enter Patient, Encounter, or Practitioner information, you'll notice that the Launch context is updated. When you're using the Azure API for FHIR, the launch context is simply a JSON document that contains information about patient, practitioner, and more. This launch context is base64 encoded and passed to the SMART on FHIR app as the launch query parameter. According to the SMART on FHIR specification, this variable is opaque to the SMART on FHIR app and passed on to the identity provider.

The SMART on FHIR proxy uses this information to populate fields in the token response. The SMART on FHIR app can use these fields to control which patient it requests data for and how it renders the application on the screen. The SMART on FHIR proxy supports the following fields:

• patient
• encounter
• practitioner
• need_patient_banner
• smart_style_url

These fields are meant to provide guidance to the app, but they don't convey any security information. A SMART on FHIR application can ignore them.

Notice that the SMART on FHIR app launcher updates the Launch URL information at the bottom of the page. Select Launch to start the sample app.