Do not try to create/drop check constraint on mysql < 8

db/migrations/20250225132929_add_apps_file_based_service_binding_feature_columns.rb

@@ -16,15 +16,15 @@
       add_column :apps, :service_binding_k8s_enabled, :boolean, default: false, null: false unless schema(:apps).map(&:first).include?(:service_binding_k8s_enabled)
       add_column :apps, :file_based_vcap_services_enabled, :boolean, default: false, null: false unless schema(:apps).map(&:first).include?(:file_based_vcap_services_enabled)
 
-      unless check_constraint_exists?(self)
+      if check_constraint_supported?(self) && !check_constraint_exists?(self)
         run('ALTER TABLE apps ADD CONSTRAINT only_one_sb_feature_enabled CHECK (NOT (service_binding_k8s_enabled AND file_based_vcap_services_enabled))')
       end
     end
   end
 
   down do
     alter_table :apps do
-      drop_constraint :only_one_sb_feature_enabled if check_constraint_exists?(@db)
+      drop_constraint :only_one_sb_feature_enabled if check_constraint_supported?(@db) && check_constraint_exists?(@db)
       drop_column :service_binding_k8s_enabled if @db.schema(:apps).map(&:first).include?(:service_binding_k8s_enabled)
       drop_column :file_based_vcap_services_enabled if @db.schema(:apps).map(&:first).include?(:file_based_vcap_services_enabled)
     end
@@ -39,3 +39,9 @@ def check_constraint_exists?(database)
                                                            CONSTRAINT_NAME: 'only_one_sb_feature_enabled').any?
   end
 end
+
+# check constraints are not available in Mysql versions < 8
+# this is also enforced on application level, so it should be fine not to create it on that version
+def check_constraint_supported?(database)
+  database.database_type == :postgres || (database.database_type == :mysql && database.server_version >= 80_000)
+end

spec/migrations/20250225132929_add_apps_file_based_service_binding_feature_columns_spec.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 require 'migrations/helpers/migration_shared_context'
 
-RSpec.describe 'migration to add service_binding_k8s_enabled column to apps table', isolation: :truncation, type: :migration do
+RSpec.describe 'migration to add file-based service binding feature columns to apps table', isolation: :truncation, type: :migration do
   include_context 'migration' do
     let(:migration_filename) { '20250225132929_add_apps_file_based_service_binding_feature_columns.rb' }
   end
@@ -44,7 +44,7 @@
             expect { run_migration }.not_to raise_error
             expect(db[:apps].columns).to include(:service_binding_k8s_enabled)
             expect(db[:apps].columns).to include(:file_based_vcap_services_enabled)
-            expect(check_constraint_exists?(db)).to be(true)
+            expect(check_constraint_exists?(db)).to be(true) if check_constraint_supported?(db)
           end
         end
       end
@@ -83,38 +83,56 @@
             expect { run_migration }.not_to raise_error
             expect(db[:apps].columns).to include(:service_binding_k8s_enabled)
             expect(db[:apps].columns).to include(:file_based_vcap_services_enabled)
-            expect(check_constraint_exists?(db)).to be(true)
+            expect(check_constraint_exists?(db)).to be(true) if check_constraint_supported?(db)
           end
         end
       end
 
       describe 'check constraint' do
-        it 'adds the check constraint' do
-          expect(check_constraint_exists?(db)).to be(false)
-          run_migration
-          expect(check_constraint_exists?(db)).to be(true)
-        end
+        context 'when supported' do
+          before do
+            skip 'check constraint not supported by db' unless check_constraint_supported?(db)
+          end
 
-        it 'forbids setting both features to true' do
-          run_migration
-          expect { db[:apps].insert(guid: 'some_app', file_based_vcap_services_enabled: true, service_binding_k8s_enabled: true) }.to(raise_error do |error|
-            expect(error.inspect).to include('only_one_sb_feature_enabled', 'violate')
-          end)
-        end
+          it 'adds the check constraint' do
+            expect(check_constraint_exists?(db)).to be(false)
+            run_migration
+            expect(check_constraint_exists?(db)).to be(true)
+          end
 
-        context 'when it already exists' do
-          before do
-            db.add_column :apps, :service_binding_k8s_enabled, :boolean, default: false, null: false, if_not_exists: true
-            db.add_column :apps, :file_based_vcap_services_enabled, :boolean, default: false, null: false, if_not_exists: true
-            db.alter_table :apps do
-              add_constraint(name: :only_one_sb_feature_enabled) do
-                Sequel.lit('NOT (service_binding_k8s_enabled AND file_based_vcap_services_enabled)')
+          it 'forbids setting both features to true' do
+            run_migration
+            expect { db[:apps].insert(guid: 'some_app', file_based_vcap_services_enabled: true, service_binding_k8s_enabled: true) }.to(raise_error do |error|
+              expect(error.inspect).to include('only_one_sb_feature_enabled', 'violate')
+            end)
+          end
+
+          context 'when it already exists' do
+            before do
+              db.add_column :apps, :service_binding_k8s_enabled, :boolean, default: false, null: false, if_not_exists: true
+              db.add_column :apps, :file_based_vcap_services_enabled, :boolean, default: false, null: false, if_not_exists: true
+              db.alter_table :apps do
+                add_constraint(name: :only_one_sb_feature_enabled) do
+                  Sequel.lit('NOT (service_binding_k8s_enabled AND file_based_vcap_services_enabled)')
+                end
               end
             end
+
+            it 'does not fail' do
+              expect { run_migration }.not_to raise_error
+            end
+          end
+        end
+
+        context 'when not supported' do
+          before do
+            skip 'check constraint supported by db' if check_constraint_supported?(db)
           end
 
           it 'does not fail' do
             expect { run_migration }.not_to raise_error
+            expect(db[:apps].columns).to include(:service_binding_k8s_enabled)
+            expect(db[:apps].columns).to include(:file_based_vcap_services_enabled)
           end
         end
       end
@@ -178,25 +196,43 @@
       end
 
       describe 'check constraint' do
-        it 'removes the check constraint' do
-          expect(check_constraint_exists?(db)).to be(true)
-          run_rollback
-          expect(check_constraint_exists?(db)).to be(false)
+        context 'when supported' do
+          before do
+            skip 'check constraint not supported by db' unless check_constraint_supported?(db)
+          end
+
+          it 'removes the check constraint' do
+            expect(check_constraint_exists?(db)).to be(true)
+            run_rollback
+            expect(check_constraint_exists?(db)).to be(false)
+          end
+
+          context 'when it does not exist' do
+            before do
+              db.alter_table :apps do
+                drop_constraint :only_one_sb_feature_enabled
+              end
+            end
+
+            it 'does not fail' do
+              expect(check_constraint_exists?(db)).to be(false)
+              expect { run_rollback }.not_to raise_error
+              expect(db[:apps].columns).not_to include(:service_binding_k8s_enabled)
+              expect(db[:apps].columns).not_to include(:file_based_vcap_services_enabled)
+              expect(check_constraint_exists?(db)).to be(false)
+            end
+          end
         end
 
-        context 'when it does not exist' do
+        context 'when not supported' do
           before do
-            db.alter_table :apps do
-              drop_constraint :only_one_sb_feature_enabled
-            end
+            skip 'check constraint supported by db' if check_constraint_supported?(db)
           end
 
           it 'does not fail' do
-            expect(check_constraint_exists?(db)).to be(false)
             expect { run_rollback }.not_to raise_error
             expect(db[:apps].columns).not_to include(:service_binding_k8s_enabled)
             expect(db[:apps].columns).not_to include(:file_based_vcap_services_enabled)
-            expect(check_constraint_exists?(db)).to be(false)
           end
         end
       end