Add data migration to remove duplicate DastSiteTokens with same token

db/post_migrate/20210825182303_remove_duplicate_dast_site_tokens_with_same_token.rb

+# frozen_string_literal: true
+
+class RemoveDuplicateDastSiteTokensWithSameToken < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  INDEX_NAME = 'index_dast_site_token_on_token'
+
+  # rubocop: disable Migration/AddIndex
+  def up
+    execute("WITH duplicate_tokens AS(
+                  SELECT id, rank() OVER (PARTITION BY token ORDER BY id) r FROM dast_site_tokens
+                )
+                DELETE FROM dast_site_tokens c USING duplicate_tokens t
+                WHERE c.id = t.id AND t.r > 1;")
+
+    add_index :dast_site_tokens, :token, name: INDEX_NAME, unique: true
+  end
+
+  # rubocop: disable Migration/RemoveIndex
+  def down
+    remove_index :dast_site_tokens, :token, name: INDEX_NAME
+  end
+end

db/schema_migrations/20210825182303

+a7f4911fcb9ab939a6e5e9a6e5e927fd6828ff062324d8483d78c8f8a4ded4e6
\ No newline at end of file

db/structure.sql

@@ -24821,6 +24821,8 @@ CREATE UNIQUE INDEX index_dast_site_profiles_pipelines_on_ci_pipeline_id ON dast
 
 CREATE UNIQUE INDEX index_dast_site_token_on_project_id_and_url ON dast_site_tokens USING btree (project_id, url);
 
+CREATE UNIQUE INDEX index_dast_site_token_on_token ON dast_site_tokens USING btree (token);
+
 CREATE INDEX index_dast_site_tokens_on_project_id ON dast_site_tokens USING btree (project_id);
 
 CREATE INDEX index_dast_site_validations_on_dast_site_token_id ON dast_site_validations USING btree (dast_site_token_id);

spec/migrations/remove_duplicate_dast_site_tokens_with_same_token_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+require_migration!
+
+RSpec.describe RemoveDuplicateDastSiteTokensWithSameToken do
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:dast_site_tokens) { table(:dast_site_tokens) }
+  let!(:namespace) { namespaces.create!(id: 1, name: 'group', path: 'group') }
+  let!(:project1) { projects.create!(id: 1, namespace_id: namespace.id, path: 'project1') }
+  # create non duplicate dast site token
+  let!(:dast_site_token1) { dast_site_tokens.create!(project_id: project1.id, url: 'https://gitlab.com', token: SecureRandom.uuid) }
+
+  context 'when duplicate dast site tokens exists' do
+    # create duplicate dast site token
+    let_it_be(:duplicate_token) { 'duplicate_token' }
+    let_it_be(:other_duplicate_token) { 'other_duplicate_token' }
+
+    let!(:project2) { projects.create!(id: 2, namespace_id: namespace.id, path: 'project2') }
+    let!(:dast_site_token2) { dast_site_tokens.create!(project_id: project2.id, url: 'https://gitlab2.com', token: duplicate_token) }
+    let!(:dast_site_token3) { dast_site_tokens.create!(project_id: project2.id, url: 'https://gitlab3.com', token: duplicate_token) }
+    let!(:dast_site_token4) { dast_site_tokens.create!(project_id: project2.id, url: 'https://gitlab4.com', token: duplicate_token) }
+
+    let!(:project3) { projects.create!(id: 3, namespace_id: namespace.id, path: 'project3') }
+    let!(:dast_site_token5) { dast_site_tokens.create!(project_id: project3.id, url: 'https://gitlab2.com', token: other_duplicate_token) }
+    let!(:dast_site_token6) { dast_site_tokens.create!(project_id: project3.id, url: 'https://gitlab3.com', token: other_duplicate_token) }
+    let!(:dast_site_token7) { dast_site_tokens.create!(project_id: project3.id, url: 'https://gitlab4.com', token: other_duplicate_token) }
+
+    describe 'migration up' do
+      it 'does remove duplicated dast site tokens with the same token' do
+        expect(dast_site_tokens.count).to eq(7)
+        expect(dast_site_tokens.where(token: duplicate_token).size).to eq(3)
+
+        migrate!
+
+        expect(dast_site_tokens.count).to eq(3)
+        expect(dast_site_tokens.where(token: duplicate_token).size).to eq(1)
+      end
+    end
+  end
+
+  context 'when duplicate dast site tokens do not exist' do
+    let!(:dast_site_token5) { dast_site_tokens.create!(project_id: 1, url: 'https://gitlab5.com', token: SecureRandom.uuid) }
+
+    describe 'migration up' do
+      it 'does not remove any dast site tokens' do
+        expect { migrate! }.not_to change(dast_site_tokens, :count)
+      end
+    end
+  end
+end