Fix Error 500 when viewing a commit with a GPG signature in Geo

Closes gitlab-org/gitlab-ee#4825

changelogs/unreleased/sh-fix-geo-error-500-gpg-commit.yml

+---
+title: Fix Error 500 when viewing a commit with a GPG signature in Geo
+merge_request:
+author:
+type: fixed

lib/gitlab/gpg/commit.rb

@@ -60,7 +60,9 @@ module Gitlab
 
       def create_cached_signature!
         using_keychain do |gpg_key|
-          GpgSignature.create!(attributes(gpg_key))
+          signature = GpgSignature.new(attributes(gpg_key))
+          signature.save! unless Gitlab::Database.read_only?
+          signature
         end
       end
 

spec/lib/gitlab/gpg/commit_spec.rb

@@ -49,7 +49,9 @@ describe Gitlab::Gpg::Commit do
           end
 
           it 'returns a valid signature' do
-            expect(described_class.new(commit).signature).to have_attributes(
+            signature = described_class.new(commit).signature
+
+            expect(signature).to have_attributes(
               commit_sha: commit_sha,
               project: project,
               gpg_key: gpg_key,
@@ -58,9 +60,31 @@ describe Gitlab::Gpg::Commit do
               gpg_key_user_email: GpgHelpers::User1.emails.first,
               verification_status: 'verified'
             )
+            expect(signature.persisted?).to be_truthy
           end
 
           it_behaves_like 'returns the cached signature on second call'
+
+          context 'read-only mode' do
+            before do
+              allow(Gitlab::Database).to receive(:read_only?).and_return(true)
+            end
+
+            it 'does not create a cached signature' do
+              signature = described_class.new(commit).signature
+
+              expect(signature).to have_attributes(
+                commit_sha: commit_sha,
+                project: project,
+                gpg_key: gpg_key,
+                gpg_key_primary_keyid: GpgHelpers::User1.primary_keyid,
+                gpg_key_user_name: GpgHelpers::User1.names.first,
+                gpg_key_user_email: GpgHelpers::User1.emails.first,
+                verification_status: 'verified'
+              )
+              expect(signature.persisted?).to be_falsey
+            end
+          end
         end
 
         context 'commit signed with a subkey' do