use new firebase admin sdk private key

README.md

@@ -29,9 +29,11 @@ response.raw_body # => '{"name":"-INOQPH-aV_psbk3ZXEX"}'
 
 If you have a read-only namespace, set your secret key as follows:
 ```ruby
-firebase = Firebase::Client.new(base_uri, secret_key)
+# Using Firebase Admin SDK private key
+firebase = Firebase::Client.new(base_uri, "/path/to/private_key.json")
 
-response = firebase.push("todos", { :name => 'Pick the milk', :'.priority' => 1 })
+# Using Firebase Database Secret (deprecated)
+firebase = Firebase::Client.new(base_uri, db_secret)
 ```
 
 You can now pass custom query options to firebase:

firebase.gemspec

@@ -23,6 +23,7 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'httpclient', '>= 2.5.3'
   s.add_runtime_dependency 'json'
+  s.add_runtime_dependency 'googleauth'
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rdoc'
   s.add_development_dependency 'rspec'

lib/firebase.rb

@@ -1,5 +1,6 @@
 require 'firebase/response'
 require 'firebase/server_value'
+require 'googleauth'
 require 'httpclient'
 require 'json'
 require 'uri'
@@ -13,13 +14,22 @@ def initialize(base_uri, auth=nil)
         raise ArgumentError.new('base_uri must be a valid https uri')
       end
       base_uri += '/' unless base_uri.end_with?('/')
+      default_header = {
+        'Content-Type' => 'application/json'
+      }
+      if auth && File.file?(auth)
+        # Using Admin SDK private key file
+        scopes = %w(https://www.googleapis.com/auth/firebase.database https://www.googleapis.com/auth/userinfo.email)
+        credentials = Google::Auth::DefaultCredentials.make_creds(json_key_io: File.open(auth), scope: scopes)
+        default_header = credentials.apply(default_header)
+      else
+        # Using deprecated Database Secret
+        @auth = auth
+      end
       @request = HTTPClient.new({
         :base_url => base_uri,
-        :default_header => {
-          'Content-Type' => 'application/json'
-        }
+        :default_header => default_header
       })
-      @auth = auth
     end
 
     # Writes and returns the data

spec/firebase_spec.rb

@@ -124,7 +124,7 @@
   end
 
   describe "http processing" do
-    it "sends custom auth" do
+    it "sends custom auth query" do
       firebase = Firebase::Client.new('https://test.firebaseio.com', 'secret')
       expect(firebase.request).to receive(:request).with(:get, "todos.json", {
         :body => nil,
@@ -133,5 +133,21 @@
       })
       firebase.get('todos', :foo => 'bar')
     end
+
+    it "sets custom auth header" do
+      expect(File).to receive(:file?).with('test_private_key.json').and_return(true)
+      expect(File).to receive(:open).with('test_private_key.json').and_return('private key')
+      credentials = double()
+      expect(credentials).to receive(:apply).with({ 'Content-Type' => 'application/json' }).and_return({ :authorization => 'Bearer abcdef', 'Content-Type' => 'application/json' })
+      expect(Google::Auth::DefaultCredentials).to receive(:make_creds).with(json_key_io: 'private key', scope: instance_of(Array)).and_return(credentials)
+      expect(HTTPClient).to receive(:new).with({
+        :base_url => 'https://test.firebaseio.com/',
+        :default_header => {
+          :authorization => 'Bearer abcdef',
+          'Content-Type' => 'application/json'
+        }
+      })
+      firebase = Firebase::Client.new('https://test.firebaseio.com/', 'test_private_key.json')
+    end
   end
 end