Use the server's base URL without relative URL part when creating links in JIRA

Signed-off-by: Rémy Coutable <remy@rymai.me>

CHANGELOG.md

@@ -29,6 +29,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 - Do not show tooltip for active element !7105 (winniehell)
 - Escape ref and path for relative links !6050 (winniehell)
 - Fixed link typo on /help/ui to Alerts section. !6915 (Sam Rose)
+- Fix broken issue/merge request links in JIRA comments. !6143 (Brian Kintz)
 - Fix filtering of milestones with quotes in title (airatshigapov)
 - Refactor less readable existance checking code from CoffeeScript !6289 (jlogandavison)
 - Update mail_room and enable sentinel support to Reply By Email (!7101)

app/models/project_services/jira_service.rb

@@ -237,7 +237,7 @@ class JiraService < IssueTrackerService
   end
   def resource_url(resource)
-    "#{Settings.gitlab['url'].chomp("/")}#{resource}"
+    "#{Settings.gitlab.base_url.chomp("/")}#{resource}"
   end
   def build_entity_url(entity_name, entity_id)

spec/models/project_services/jira_service_spec.rb

 require 'spec_helper'
+include Gitlab::Routing.url_helpers
 describe JiraService, models: true do
   describe "Associations" do
@@ -66,6 +67,27 @@ describe JiraService, models: true do
       ).once
     end
+    it "references the GitLab commit/merge request" do
+      @jira_service.execute(merge_request, ExternalIssue.new("JIRA-123", project))
+
+      expect(WebMock).to have_requested(:post, @comment_url).with(
+        body: /#{Gitlab.config.gitlab.url}\/#{project.path_with_namespace}\/commit\/#{merge_request.diff_head_sha}/
+      ).once
+    end
+
+    it "references the GitLab commit/merge request (relative URL)" do
+      stub_config_setting(relative_url_root: '/gitlab')
+      stub_config_setting(url: Settings.send(:build_gitlab_url))
+
+      Project.default_url_options[:script_name] = "/gitlab"
+
+      @jira_service.execute(merge_request, ExternalIssue.new("JIRA-123", project))
+
+      expect(WebMock).to have_requested(:post, @comment_url).with(
+        body: /#{Gitlab.config.gitlab.url}\/#{project.path_with_namespace}\/commit\/#{merge_request.diff_head_sha}/
+      ).once
+    end
+
     it "calls the api with jira_issue_transition_id" do
       @jira_service.jira_issue_transition_id = 'this-is-a-custom-id'
       @jira_service.execute(merge_request, ExternalIssue.new("JIRA-123", project))