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.

y 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 eyJ0e

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 
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.