fix(block): ignore inaccessible legacy snapshot in diff

Author: Laure-di

internal/services/block/helpers_block.go

@@ -2,6 +2,7 @@ package block
 
 import (
 	"context"
+	"errors"
 	"time"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/customdiff"
@@ -56,6 +57,28 @@ func customDiffCannotShrink(key string) schema.CustomizeDiffFunc {
 	})
 }
 
+func customDiffSnapshot(key string) schema.CustomizeDiffFunc {
+	return func(ctx context.Context, diff *schema.ResourceDiff, i any) error {
+		if !diff.HasChange(key) {
+			return nil
+		}
+		oldValue, NewValue := diff.GetChange(key)
+		blockAPI, zone, _, err := NewAPIWithZoneAndID(i, diff.Id())
+		if err != nil {
+			return errors.New(err.Error())
+		}
+		_, err = blockAPI.GetSnapshot(&block.GetSnapshotRequest{
+			Zone:       zone,
+			SnapshotID: oldValue.(string),
+		})
+		if (httperrors.Is403(err) || httperrors.Is404(err)) && NewValue == nil {
+			return nil
+		}
+
+		return diff.ForceNew("snapshot_id")
+	}
+}
+
 func migrateInstanceToBlockVolume(ctx context.Context, api *instancehelpers.BlockAndInstanceAPI, zone scw.Zone, volumeID string, timeout time.Duration) (*block.Volume, error) {
 	instanceVolumeResp, err := api.GetVolume(&instance.GetVolumeRequest{
 		Zone:     zone,

internal/services/block/volume.go

@@ -54,7 +54,6 @@ func ResourceVolume() *schema.Resource {
 			"snapshot_id": {
 				Type:             schema.TypeString,
 				Optional:         true,
-				ForceNew:         true,
 				Description:      "The snapshot to create the volume from",
 				DiffSuppressFunc: dsf.Locality,
 			},
@@ -79,6 +78,7 @@ func ResourceVolume() *schema.Resource {
 		},
 		CustomizeDiff: customdiff.All(
 			customDiffCannotShrink("size_in_gb"),
+			customDiffSnapshot("snapshot_id"),
 		),
 	}
 }