fix(dockerhub-migration): prevent duplicate migrated dockerhub entries EE-2042 (#6083)

* fix(migration) make dockerhub registry migration idempotent EE-2042

* add missing changes to make updateDockerhubToDB32 idempotent

* add tests for bad migrations

api/bolt/migrator/migrate_dbversion34_test.go

@@ -0,0 +1,108 @@
+package migrator
+
+import (
+	"os"
+	"path"
+	"testing"
+	"time"
+
+	"github.com/boltdb/bolt"
+	portainer "github.com/portainer/portainer/api"
+	"github.com/portainer/portainer/api/bolt/dockerhub"
+	"github.com/portainer/portainer/api/bolt/endpoint"
+	"github.com/portainer/portainer/api/bolt/internal"
+	"github.com/portainer/portainer/api/bolt/registry"
+	"github.com/stretchr/testify/assert"
+)
+
+const (
+	db35TestFile = "portainer-mig-35.db"
+	username     = "portainer"
+	password     = "password"
+)
+
+func setupDB35Test(t *testing.T) *Migrator {
+	is := assert.New(t)
+	dbConn, err := bolt.Open(path.Join(t.TempDir(), db35TestFile), 0600, &bolt.Options{Timeout: 1 * time.Second})
+	is.NoError(err, "failed to init testing DB connection")
+
+	// Create an old style dockerhub authenticated account
+	dockerhubService, err := dockerhub.NewService(&internal.DbConnection{DB: dbConn})
+	is.NoError(err, "failed to init testing registry service")
+	err = dockerhubService.UpdateDockerHub(&portainer.DockerHub{true, username, password})
+	is.NoError(err, "failed to create dockerhub account")
+
+	registryService, err := registry.NewService(&internal.DbConnection{DB: dbConn})
+	is.NoError(err, "failed to init testing registry service")
+
+	endpointService, err := endpoint.NewService(&internal.DbConnection{DB: dbConn})
+	is.NoError(err, "failed to init endpoint service")
+
+	m := &Migrator{
+		db:               dbConn,
+		dockerhubService: dockerhubService,
+		registryService:  registryService,
+		endpointService:  endpointService,
+	}
+
+	return m
+}
+
+// TestUpdateDockerhubToDB32 tests a normal upgrade
+func TestUpdateDockerhubToDB32(t *testing.T) {
+	is := assert.New(t)
+	m := setupDB35Test(t)
+	defer m.db.Close()
+	defer os.Remove(db35TestFile)
+
+	if err := m.updateDockerhubToDB32(); err != nil {
+		t.Errorf("failed to update settings: %v", err)
+	}
+
+	// Verify we have a single registry were created
+	registries, err := m.registryService.Registries()
+	is.NoError(err, "failed to read registries from the RegistryService")
+	is.Equal(len(registries), 1, "only one migrated registry expected")
+}
+
+// TestUpdateDockerhubToDB32_with_duplicate_migrations tests an upgrade where in earlier versions a broken migration
+// created a large number of duplicate "dockerhub migrated" registry entries.
+func TestUpdateDockerhubToDB32_with_duplicate_migrations(t *testing.T) {
+	is := assert.New(t)
+	m := setupDB35Test(t)
+	defer m.db.Close()
+	defer os.Remove(db35TestFile)
+
+	// Create lots of duplicate entries...
+	registry := &portainer.Registry{
+		Type:             portainer.DockerHubRegistry,
+		Name:             "Dockerhub (authenticated - migrated)",
+		URL:              "docker.io",
+		Authentication:   true,
+		Username:         "portainer",
+		Password:         "password",
+		RegistryAccesses: portainer.RegistryAccesses{},
+	}
+
+	for i := 1; i < 150; i++ {
+		err := m.registryService.CreateRegistry(registry)
+		assert.NoError(t, err, "create registry failed")
+	}
+
+	// Verify they were created
+	registries, err := m.registryService.Registries()
+	is.NoError(err, "failed to read registries from the RegistryService")
+	is.Condition(func() bool {
+		return len(registries) > 1
+	}, "expected multiple duplicate registry entries")
+
+	// Now run the migrator
+	if err := m.updateDockerhubToDB32(); err != nil {
+		t.Errorf("failed to update settings: %v", err)
+	}
+
+	// Verify we have a single registry were created
+	registries, err = m.registryService.Registries()
+	is.NoError(err, "failed to read registries from the RegistryService")
+	is.Equal(len(registries), 1, "only one migrated registry expected")
+}