Can't get client-credentials access token to authorize Power BI

Question

I'm trying to use the Power BI REST API, using an access token acquired with the "client credentials" method, but I keep getting 403 Forbidden on my requests.

My code follows the pattern demonstrated in this AzureAD sample. In fact, to isolate this problem, I'm running that sample code (with my own values in the parameters.json, of course):

{ 
  expiresIn: 3599,
  tokenType: 'Bearer',
  expiresOn: Tue Sep 01 2015 16:56:07 GMT-0500 (CDT),
  resource: '00000002-0000-0000-c000-000000000000',
  accessToken: 'eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsIng1dCI6Ik1uQ19WWmNBVGZNNXBPWWlKSE1iYTlnb0VLWSIsImtpZCI6Ik1uQ19WWmNBVGZNNXBPWWlKSE1iYTlnb0VLWSJ9.eyJhdWQiOiIwMDAwMDAwMi0wMDAwLTAwMDAtYzAwMC0wMDAwMDAwMDAwMDAiLCJpc3MiOiJodHRwczovL3N0cy53aW5kb3dzLm5ldC8xM2QxNzIwNC0wZGU2LTQ1NzQtOTgzYS05NjFhYjk0M2M3Y2UvIiwiaWF0IjoxNDQxMTQwNjcwLCJuYmYiOjE0NDExNDA2NzAsImV4cCI6MTQ0MTE0NDU3MCwidmVyIjoiMS4wIiwidGlkIjoiMTNkMTcyMDQtMGRlNi00NTc0LTk4M2EtOTYxYWI5NDNjN2NlIiwib2lkIjoiYzM1ZWQyYTktYTYzZS00YzAwLThmYmYtY2FlYjlmZjYwMjYwIiwic3ViIjoiYzM1ZWQyYTktYTYzZS00YzAwLThmYmYtY2FlYjlmZjYwMjYwIiwiaWRwIjoiaHR0cHM6Ly9zdHMud2luZG93cy5uZXQvMTNkMTcyMDQtMGRlNi00NTc0LTk4M2EtOTYxYWI5NDNjN2NlLyIsImFwcGlkIjoiNDQ2Y2Y5OTItMDQzYS00YjgxLWJhYzQtY2RlZWYyNGFhNzFjIiwiYXBwaWRhY3IiOiIxIn0.YTGJfdW1wP09bDHwwsv3FPAmEpmQdc_kifvgY-1KjhkZWANfYtd050wfeZdNgMUeSPZyFdWnoBjnJ4xrlDtnsADwV1Grr6TXYcymPLofbY-xy0cjyvzxTmM11DJ9XN8A4tkgvK0jtR-YyIjPw5EKJSKyeEbD9U3mWsE_gu7IzKzXl8e-dfVAqRYS6WHZy6_0FaNmppPDls5s_QIPOHofFSiWVISw41Mz0fQnP2QEGyceOCvKYJtrUOCDwfVuwFS-gSLmYvEGOJfmIjftP3srda0JPirVzBeU0IFJJ1KW81kE5cfKw1KkBB04VVetRUs_7HqloYaKKiTybauhXAodRQ',
  isMRRT: true,
  _clientId: '[snip]',
  _authority: 'https://login.windows.net/[snip]' 
}

When I use that access token in a curl request, as follows, I get a 403:

curl -vv -X GET https://api.powerbi.com/v1.0/myorg/datasets -H"Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsIng1dCI6Ik1uQ19WWmNBVGZNNXBPWWlKSE1iYTlnb0VLWSIsImtpZCI6Ik1uQ19WWmNBVGZNNXBPWWlKSE1iYTlnb0VLWSJ9.eyJhdWQiOiIwMDAwMDAwMi0wMDAwLTAwMDAtYzAwMC0wMDAwMDAwMDAwMDAiLCJpc3MiOiJodHRwczovL3N0cy53aW5kb3dzLm5ldC8xM2QxNzIwNC0wZGU2LTQ1NzQtOTgzYS05NjFhYjk0M2M3Y2UvIiwiaWF0IjoxNDQxMTQwNjcwLCJuYmYiOjE0NDExNDA2NzAsImV4cCI6MTQ0MTE0NDU3MCwidmVyIjoiMS4wIiwidGlkIjoiMTNkMTcyMDQtMGRlNi00NTc0LTk4M2EtOTYxYWI5NDNjN2NlIiwib2lkIjoiYzM1ZWQyYTktYTYzZS00YzAwLThmYmYtY2FlYjlmZjYwMjYwIiwic3ViIjoiYzM1ZWQyYTktYTYzZS00YzAwLThmYmYtY2FlYjlmZjYwMjYwIiwiaWRwIjoiaHR0cHM6Ly9zdHMud2luZG93cy5uZXQvMTNkMTcyMDQtMGRlNi00NTc0LTk4M2EtOTYxYWI5NDNjN2NlLyIsImFwcGlkIjoiNDQ2Y2Y5OTItMDQzYS00YjgxLWJhYzQtY2RlZWYyNGFhNzFjIiwiYXBwaWRhY3IiOiIxIn0.YTGJfdW1wP09bDHwwsv3FPAmEpmQdc_kifvgY-1KjhkZWANfYtd050wfeZdNgMUeSPZyFdWnoBjnJ4xrlDtnsADwV1Grr6TXYcymPLofbY-xy0cjyvzxTmM11DJ9XN8A4tkgvK0jtR-YyIjPw5EKJSKyeEbD9U3mWsE_gu7IzKzXl8e-dfVAqRYS6WHZy6_0FaNmppPDls5s_QIPOHofFSiWVISw41Mz0fQnP2QEGyceOCvKYJtrUOCDwfVuwFS-gSLmYvEGOJfmIjftP3srda0JPirVzBeU0IFJJ1KW81kE5cfKw1KkBB04VVetRUs_7HqloYaKKiTybauhXAodRQ"

Wondering if that curl request was flawed somehow, I snooped out an access token “the wrong way” via browser webtools, and the above works fine, returning a 200 and a JSON response listing my datasets.

I did also notice that the return code is 403 (forbidden), not 401 (unauthorized), so I wondered if the authorization was okay but the permissions on the Power BI side were wrong. But I also get 403 when I use any garbage text for the access token (e.g., Authorization: Bearer foo), so I discarded that theory.

So. I think I have a valid test, and I’m getting what I think is a valid access token (from that client-credentials-sample.js code), but it’s still not working. What am I missing?

Answer 1

With the assistance of some Microsoft folks (thanks, Jon Gallant & Josh Caplan), I've learned that authenticating with an OAuth client-credentials flow, as I was doing with that JavaScript sample, provides insufficient access. To use Power BI, authentication needs to be based on a particular user.

I tried using:

1. the similar JavaScript sample username-password-sample.js
2. a resource value of https://analysis.windows.net/powerbi/api (thanks, slugslog)
3. adding username and password to the parameters.json

That got me closer, but I was still getting a 400 response: "error_description":"AADSTS90014: The request body must contain the following parameter: 'client_secret or client_assertion'. …".

A hack to the adal-node library (hardcoding the client secret, i.e., oauthParameters[OAuth2Parameters.CLIENT_SECRET] = "my-client-secret"; after line 217 of token-request.js) was enough to get back an access token which works in the Authorization header for my original curl call.

Of course hardcoding that value in there isn't my final solution. I don't plan to use the adal-node library, anyway. But as far as this proof-of-concept for this authentication case goes, that's the answer I came to.