How to get the OAuth2 token for Microsoft Azure using Ruby and add it to your Http connection header. Install in command line first: gem install nice_http or in case you use linux: sudo gem install nice_http

get_bearer_token.rb

require 'nice_http'
require "addressable/uri"

# Create on management.azure.com a new directory or 
#   select the one you want
# Create an application on that directory if you want to
# Be sure api permissions are the ones you need, 
#   for example Access Azure Service Management
# Get the client_id and the tenant_id
# Create a client secret and get it
client_id = "YOUR CLIENT ID"
tenant_id = "YOUR TENANT ID"
client_secret = "YOUR CLIENT SECRET"
resource = 'https://management.azure.com/' #The resource you want to log in

server = 'https://login.microsoftonline.com'
path = "/#{tenant_id}/oauth2/token"

uri = Addressable::URI.new
uri.query_values = {
    grant_type: 'client_credentials',
    client_id: client_id,
    client_secret: client_secret,
    resource: resource
}


http = NiceHttp.new(server)

req = {
    path: path,
    data: uri.query.to_s
}

resp = http.post(req)
puts "#{resp.code}: #{resp.message}"
access_token = resp.data.json(:access_token)
puts access_token


# for connecting to your resource:
NiceHttp.headers = { Authorization: "Bearer #{access_token}" }
# from now on all NiceHttp connections you create will have the Bearer token

http_res = NiceHttp.new(resource)