Extract user from authentication token - azure-api-management

Question

I have created custom Oauth2 service and configured API to use it according to the article: https://learn.microsoft.com/en-us/azure/api-management/api-management-howto-oauth2
Using Developer Portal I see that access token is sent to the API endpoint. However I need to have one more piece of information sent to my endpoint. The access token looks like this:
{"access_token":"e_Pt_0mEUKfMk7DzN7QDmb4tx6syaMM9d7Ei9UH4y1pYipErNHZFz9dU5ZmdTIvr2R4fD1GxJZY-Bsyt7tIpm7uKFScrrKRAKBVGeU3T7R1WTiBV3WglPK1OHZgOSpIY","token_type":"bearer","expires_in":3600,"user":"T81lum-5p6QvDR7l6hv7lfE52bAbA2ylWBnv9CZEzNb0B"}"
I need to extract the user property of the token and send it to API endpoint. Is it possible?
Thank you

Answer 1

Just share an idea about this. the user name is encoded in the bear token that can be parsed with JWT. You can add policy in <inbound> where you parse token and save user name to header then pass to your backend. the official document already provided the JWT parser
Jwt jwt = AsJwt(put_your_token_in_here)
String userName = jwt.Claims.GetValueOrDefault("name")
see JWT token.

Answer 2

You can parse the JSON and extract the user id, but it's going to be dependent on the language you're using.
In Node.JS, it's pretty straightforward (here assuming the auth blob is a string, and not yet parsed):
let userid = JSON.parse( auth_blob ).user;
In Java using GSON:
JsonElement jsonTree = parser.parse( auth_blob );
JsonElement userElement = jsonTree.get("user");
String user = userElement.getAsString();
and so on... searching for "parse JSON" and your language of choice will help you out there.
There's a short tutorial for how to embed a json extract in Azure here:
https://learn.microsoft.com/bs-latn-ba/azure/api-management/policies/cache-response?toc=api-management/toc.json
<!-- Extract a JSON object containing lat/long from the response and serialize it into a variable. -->
<set-variable name="latlong" value="#(((IResponse)context.Variables["response="""]).Body.As<JObject>
()["results"][0]["geometry"]["location"].ToString())"/>
So, I suppose that you could do the same thing for your auth blob:
<set-variable name="user" value="#((auth_blob).Body.As<JObject>
()["user"].ToString())"/>
Please edit if this is incorrect - I'm just guessing here.

Answer 3

You cannot retrieve user details from auth code. You can do it using an access token.
Please refer to similar question and answer here