Ability to delete files from Cellar

lib/active_storage/service/cellar_service.rb

@@ -1,6 +1,6 @@
 require 'base64'
+require 'net/http'
 require 'openssl'
-require 'uri'
 
 module ActiveStorage
   class Service::CellarService < Service
@@ -11,6 +11,16 @@ module ActiveStorage
       @bucket = bucket
     end
 
+    def delete(key)
+      instrument :delete, key: key do
+        Net::HTTP.start(@endpoint.host, @endpoint.port, use_ssl: true) do |http|
+          request = Net::HTTP::Delete.new(URI::join(@endpoint, "/#{key}"))
+          sign(request, key)
+          http.request(request)
+        end
+      end
+    end
+
     def url(key, expires_in:, filename:, disposition:, content_type:)
       instrument :url, key: key do |payload|
         generated_url = presigned_url(
@@ -45,6 +55,13 @@ module ActiveStorage
 
     private
 
+    def sign(request, key, checksum: '')
+      date = Time.now.httpdate
+      sig = signature(method: request.method, key: key, date: date, checksum: checksum)
+      request['date'] = date
+      request['authorization'] = "AWS #{@access_key_id}:#{sig}"
+    end
+
     def presigned_url(method:, key:, expires_in:, content_type: '', checksum: '', **query_params)
       expires = expires_in.from_now.to_i
 
@@ -57,10 +74,10 @@ module ActiveStorage
       generated_url = URI::join(@endpoint, "/#{key}","?#{query.to_query}").to_s
     end
 
-    def signature(method:, key:, expires:, content_type: '', checksum: '')
+    def signature(method:, key:, expires: '', date: '', content_type: '', checksum: '')
       canonicalized_amz_headers = ""
       canonicalized_resource = "/#{@bucket}/#{key}"
-      string_to_sign = "#{method}\n#{checksum}\n#{content_type}\n#{expires}\n" +
+      string_to_sign = "#{method}\n#{checksum}\n#{content_type}\n#{expires}#{date}\n" +
                        "#{canonicalized_amz_headers}#{canonicalized_resource}"
       Base64.encode64(OpenSSL::HMAC.digest(OpenSSL::Digest.new('sha1'), @secret_access_key, string_to_sign)).strip
     end

spec/lib/active_storage/service/cellar_service_spec.rb

@@ -1,5 +1,6 @@
 require 'active_storage/service/cellar_service'
 require 'cgi'
+require 'net/http'
 require 'uri'
 
 describe 'CellarService' do
@@ -19,11 +20,12 @@ describe 'CellarService' do
   after { Timecop.return }
 
   describe 'signature generation' do
+    context 'for presigned URLs' do
       subject do
         cellar_service.send(
           :signature,
           {
-          http_verb: 'GET',
+            method: 'GET',
             key: 'fichier',
             expires: 5.minutes.from_now.to_i
           }
@@ -33,6 +35,18 @@ describe 'CellarService' do
       it { is_expected.to eq('nzCsB6cip8oofkuOdvvJs6FafkA=') }
     end
 
+    context 'for server-side requests' do
+      subject do
+        Net::HTTP::Delete.new('https://rogets.cellar.services.clever-cloud.com/fichier')
+      end
+
+      before { cellar_service.send(:sign, subject, 'fichier') }
+
+      it { expect(subject['date']).to eq(Time.now.httpdate) }
+      it { expect(subject['authorization']).to eq('AWS AKIAJFTRSGRH3RXX6D5Q:nkvviwZYb1V9HDrKyJZmY3Z8sSA=') }
+    end
+  end
+
   describe 'presigned url for download' do
     subject do
       URI.parse(