feat: toggable cleanup schema prior migration (#840)

* feat(migration): cleanup prior migration

When using the annotation `kamaji.clastix.io/cleanup-prior-migration`
with a true boolean value, Kamaji will perform a clean-up on the target
DataStore to avoid stale resources when back and forth migrations occur.

Signed-off-by: Dario Tranchitella <dario@tranchitella.eu>

* docs: cleanup prior migration

Signed-off-by: Dario Tranchitella <dario@tranchitella.eu>

---------

Signed-off-by: Dario Tranchitella <dario@tranchitella.eu>

cmd/migrate/cmd.go

@@ -22,9 +22,10 @@ import (
 func NewCmd(scheme *runtime.Scheme) *cobra.Command {
 	// CLI flags
 	var (
-		tenantControlPlane string
-		targetDataStore    string
-		timeout            time.Duration
+		tenantControlPlane    string
+		targetDataStore       string
+		cleanupPriorMigration bool
+		timeout               time.Duration
 	)
 
 	cmd := &cobra.Command{
@@ -95,6 +96,20 @@ func NewCmd(scheme *runtime.Scheme) *cobra.Command {
 				return err
 			}
 			defer targetConnection.Close()
+
+			if cleanupPriorMigration {
+				log.Info("Checking if target DataStore should be clean-up prior migration")
+
+				if exists, _ := targetConnection.DBExists(ctx, tcp.Status.Storage.Setup.Schema); exists {
+					log.Info("A colliding schema on target DataStore is present, cleaning up")
+
+					if dErr := targetConnection.DeleteDB(ctx, tcp.Status.Storage.Setup.Schema); dErr != nil {
+						return fmt.Errorf("error cleaning up prior migration: %s", dErr.Error())
+					}
+
+					log.Info("Cleaning up prior migration has been completed")
+				}
+			}
 			// Start migrating from the old Datastore to the new one
 			log.Info("migration from origin to target started")
 
@@ -110,6 +125,7 @@ func NewCmd(scheme *runtime.Scheme) *cobra.Command {
 
 	cmd.Flags().StringVar(&tenantControlPlane, "tenant-control-plane", "", "Namespaced-name of the TenantControlPlane that must be migrated (e.g.: default/test)")
 	cmd.Flags().StringVar(&targetDataStore, "target-datastore", "", "Name of the Datastore to which the TenantControlPlane will be migrated")
+	cmd.Flags().BoolVar(&cleanupPriorMigration, "cleanup-prior-migration", false, "When set to true, migration job will drop existing data in the target DataStore: useful to avoid stale data when migrating back and forth between DataStores.")
 	cmd.Flags().DurationVar(&timeout, "timeout", 5*time.Minute, "Amount of time for the context timeout")
 
 	_ = cmd.MarkFlagRequired("tenant-control-plane")

docs/content/guides/datastore-migration.md

@@ -172,6 +172,11 @@ After a while, depending on the amount of data to migrate, the Tenant Control Pl
 !!! info "Leftover"
     Please, note the datastore migration leaves the data on the default datastore, so you have to remove it manually.
 
+!!! info "Avoiding stale DataStore content"
+    When migrating `TenantControlPlane` across DataStore, a collision with the __schema__ name could happen,
+    leading to unexpected results such as old data still available.
+    The annotation `kamaji.clastix.io/cleanup-prior-migration=true` allows to enforce the clean-up of the target `DataStore` schema in case of collision.
+
 ## Post migration
 After migrating data to the new datastore, complete the migration procedure by restarting the `kubelet.service` on all the tenant worker nodes.
 

internal/resources/datastore/datastore_migrate.go

@@ -6,6 +6,7 @@ package datastore
 import (
 	"context"
 	"fmt"
+	"strconv"
 
 	"github.com/prometheus/client_golang/prometheus"
 	batchv1 "k8s.io/api/batch/v1"
@@ -122,6 +123,11 @@ func (d *Migrate) CreateOrUpdate(ctx context.Context, tenantControlPlane *kamaji
 			fmt.Sprintf("--target-datastore=%s", tenantControlPlane.Spec.DataStore),
 		}
 
+		if tenantControlPlane.GetAnnotations() != nil {
+			v, _ := strconv.ParseBool(tenantControlPlane.GetAnnotations()["kamaji.clastix.io/cleanup-prior-migration"])
+			d.job.Spec.Template.Spec.Containers[0].Args = append(d.job.Spec.Template.Spec.Containers[0].Args, fmt.Sprintf("--cleanup-prior-migration=%t", v))
+		}
+
 		return nil
 	})
 	if err != nil {