Truncate Jira app key to be no longer than 64

This makes development using Gitpod easier as host names can be long.

Changelog: fixed

lib/atlassian/jira_connect.rb

@@ -8,7 +8,10 @@ module Atlassian
       end
 
       def app_key
-        "gitlab-jira-connect-#{gitlab_host}"
+        # App key must be <= 64 characters.
+        # See: https://developer.atlassian.com/cloud/jira/platform/connect-app-descriptor/#app-descriptor-structure
+
+        "gitlab-jira-connect-#{gitlab_host}"[..63]
       end
 
       private

spec/lib/atlassian/jira_connect_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+RSpec.describe Atlassian::JiraConnect do
+  describe '.app_name' do
+    subject { described_class.app_name }
+
+    it { is_expected.to eq('GitLab for Jira (localhost)') }
+  end
+
+  describe '.app_key' do
+    subject(:app_key) { described_class.app_key }
+
+    it { is_expected.to eq('gitlab-jira-connect-localhost') }
+
+    context 'host name is too long' do
+      before do
+        hostname = 'x' * 100
+
+        stub_config(gitlab: { host: hostname })
+      end
+
+      it 'truncates the key to be no longer than 64 characters', :aggregate_failures do
+        expect(app_key).to eq('gitlab-jira-connect-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx')
+      end
+    end
+  end
+end