Send checkout sha for web hooks and services

lib/gitlab/git.rb

 module Gitlab
   module Git
     BLANK_SHA = '0' * 40
+
+    def self.extract_ref_name(ref)
+      ref.gsub(/\Arefs\/(tags|heads)\//, '')
+    end
   end
 end

lib/gitlab/push_data_builder.rb

 module Gitlab
   class PushDataBuilder
-    # Produce a hash of post-receive data
-    #
-    # data = {
-    #   before: String,
-    #   after: String,
-    #   ref: String,
-    #   user_id: String,
-    #   user_name: String,
-    #   project_id: String,
-    #   repository: {
-    #     name: String,
-    #     url: String,
-    #     description: String,
-    #     homepage: String,
-    #   },
-    #   commits: Array,
-    #   total_commits_count: Fixnum
-    # }
-    #
-    def self.build(project, user, oldrev, newrev, ref, commits = [])
-      # Total commits count
-      commits_count = commits.size
+    class << self
+      # Produce a hash of post-receive data
+      #
+      # data = {
+      #   before: String,
+      #   after: String,
+      #   ref: String,
+      #   user_id: String,
+      #   user_name: String,
+      #   project_id: String,
+      #   repository: {
+      #     name: String,
+      #     url: String,
+      #     description: String,
+      #     homepage: String,
+      #   },
+      #   commits: Array,
+      #   total_commits_count: Fixnum
+      # }
+      #
+      def build(project, user, oldrev, newrev, ref, commits = [])
+        # Total commits count
+        commits_count = commits.size
 
-      # Get latest 20 commits ASC
-      commits_limited = commits.last(20)
+        # Get latest 20 commits ASC
+        commits_limited = commits.last(20)
 
-      # Hash to be passed as post_receive_data
-      data = {
-        before: oldrev,
-        after: newrev,
-        ref: ref,
-        user_id: user.id,
-        user_name: user.name,
-        project_id: project.id,
-        repository: {
-          name: project.name,
-          url: project.url_to_repo,
-          description: project.description,
-          homepage: project.web_url,
-        },
-        commits: [],
-        total_commits_count: commits_count
-      }
+        # Hash to be passed as post_receive_data
+        data = {
+          before: oldrev,
+          after: newrev,
+          ref: ref,
+          checkout_sha: checkout_sha(project.repository, newrev, ref),
+          user_id: user.id,
+          user_name: user.name,
+          project_id: project.id,
+          repository: {
+            name: project.name,
+            url: project.url_to_repo,
+            description: project.description,
+            homepage: project.web_url,
+          },
+          commits: [],
+          total_commits_count: commits_count
+        }
 
-      # For performance purposes maximum 20 latest commits
-      # will be passed as post receive hook data.
-      commits_limited.each do |commit|
-        data[:commits] << commit.hook_attrs(project)
+        # For performance purposes maximum 20 latest commits
+        # will be passed as post receive hook data.
+        commits_limited.each do |commit|
+          data[:commits] << commit.hook_attrs(project)
+        end
+
+        data
       end
 
-      data
-    end
+      # This method provide a sample data generated with
+      # existing project and commits to test web hooks
+      def build_sample(project, user)
+        commits = project.repository.commits(project.default_branch, nil, 3)
+        build(project, user, commits.last.id, commits.first.id, "refs/heads/#{project.default_branch}", commits)
+      end
 
-    # This method provide a sample data generated with
-    # existing project and commits to test web hooks
-    def self.build_sample(project, user)
-      commits = project.repository.commits(project.default_branch, nil, 3)
-      build(project, user, commits.last.id, commits.first.id, "refs/heads/#{project.default_branch}", commits)
+      def checkout_sha(repository, newrev, ref)
+        if newrev != Gitlab::Git::BLANK_SHA && ref.start_with?('refs/tags/')
+          tag_name = Gitlab::Git.extract_ref_name(ref)
+          tag = repository.find_tag(tag_name)
+          commit = repository.commit(tag.target)
+          commit.try(:sha)
+        else
+          newrev
+        end
+      end
     end
   end
 end