The Authorization header is missing

I am getting this error :{"error":{"code":"AuthenticationFailed","message":"Authentication failed. The 'Authorization' header is missing."}} whenever I am trying to test my API that is

https://management.azure.com/subscriptions/{subscriptionID}/providers/Microsoft.Compute/locations/{location}/publishers/{publisherName}/artifacttypes/vmimage/offers/{offer}/skus?api-version=2019-03-01

Can anybody suggest a solution how to set authentication header in postman or API Tester.

An easy way to get a Bearer token in order to use for Authentication header would be to use az cli.

$token =  az account get-access-token | ConvertFrom-Json

Then by accessing $token.accesstoken you will have string as shown below.

You can use this Token then with your API call as a Bearer token

$headers = @{ Authorization = "Bearer $token.accesstoken" }

Authorization is the part of HTTP Header and generally it is token which is Base64 encoded. In Postman, you can add it by clicking on "Headers" button.

You need to set up and configure Postman to obtain an Azure Active Directory token.

A full walk though is covered here - screen shots below for quick reference.

From the docs - a sample token request form.

This is a guide to use curl to get the https://medium.com/@mauridb/calling-azure-rest-api-via-curl-eb10a06127.

You can replace the place holder to your service principal in this command.

curl -vX POST -d "grant_type=client_credentials&client_id=${spClientId}&client_secret=${spSecret}&resource=https%3A%2F%2Fmanagement.azure.com%2F" https://login.microsoftonline.com/${spTenantId}/oauth2/token)