From 8c533179b0351611df07b7d712e7152fb4ca8dce Mon Sep 17 00:00:00 2001
From: Brian Neville <29639579+brianneville@users.noreply.github.com>
Date: Thu, 18 Jun 2026 15:03:08 +0100
Subject: [PATCH] containers/docker: restart containers instead of recreating

rather than removing the container and then recreating it, we
can just call StartContainer on the container again.
---
 containers/docker/container_start.go  |  6 +++-
 containers/docker/container_update.go | 40 ++++-----------------------
 2 files changed, 10 insertions(+), 36 deletions(-)

diff --git a/containers/docker/container_start.go b/containers/docker/container_start.go
index 11eb488..d82b00e 100644
--- a/containers/docker/container_start.go
+++ b/containers/docker/container_start.go
@@ -34,7 +34,11 @@ func (m *Manager) ContainerRestart(ctx context.Context, instance string, _ ...op
 		return status.Errorf(codes.Aborted, "expected container state to be %q, got %q",
 			container.StateExited, j.State.Status)
 	}
-	return m.restartContainer(ctx, j, true)
+	if err := m.client.ContainerStart(ctx, instance, container.StartOptions{}); err != nil {
+		return status.Errorf(codes.Internal,
+			"failed when starting container: %v", err)
+	}
+	return nil
 }
 
 // ContainerStart starts a container provided the image exists and that the ports requested are not
diff --git a/containers/docker/container_update.go b/containers/docker/container_update.go
index e6768a7..177f088 100644
--- a/containers/docker/container_update.go
+++ b/containers/docker/container_update.go
@@ -76,46 +76,16 @@ func (m *Manager) performContainerUpdate(ctx context.Context, instance, image, t
 	// There was some error, let's try to restore previous state.
 	errPfx := fmt.Sprintf("failed to update instance %s due to: %v", instance, err)
 
-	if recreateErr := m.restartContainer(ctx, oldCntJSON,
-		false); recreateErr != nil {
-		s, ok := status.FromError(recreateErr)
-		if !ok {
-			return "", fmt.Errorf(
-				"programming error: restartContainer"+
-					" should return status error code, got %s: %s",
-				errPfx, recreateErr)
-		}
-		return "", status.Errorf(s.Code(), "%s; restoration of previous state %s", errPfx, recreateErr)
-	}
-
-	return instance, status.Errorf(codes.Internal, "%s; yet, restoration of previous state succeeded", errPfx)
-}
-
-// restartContainer recreates a container given a particular config.
-// it is expected that the container in question has been stopped by the point this is called.
-func (m *Manager) restartContainer(ctx context.Context, oldCntJSON types.ContainerJSON,
-	needsRemoval bool) error {
-	instanceName := strings.Replace(oldCntJSON.Name, "/", "", 1)
-	if needsRemoval {
-		if err := m.client.ContainerRemove(ctx, instanceName,
-			container.RemoveOptions{}); err != nil {
-			return status.Errorf(codes.Internal,
-				"failed when removing container: %v", err)
-		}
-	}
-	resp, err := m.client.ContainerCreate(ctx,
-		oldCntJSON.Config, oldCntJSON.HostConfig, &network.NetworkingConfig{},
-		nil, instanceName)
+	resp, err := m.client.ContainerCreate(ctx, oldCntJSON.Config, oldCntJSON.HostConfig, &network.NetworkingConfig{}, nil, instance)
 	if err != nil {
-		return status.Errorf(codes.Internal,
-			"failed when creating container: %v", err)
+		return "", status.Errorf(codes.Internal, "%s; restoration of previous state failed when creating container: %v", errPfx, err)
 	}
 
 	if err := m.client.ContainerStart(ctx, resp.ID, container.StartOptions{}); err != nil {
-		return status.Errorf(codes.Internal,
-			"failed when starting container: %v", err)
+		return "", status.Errorf(codes.Internal, "%s; restoration of previous state failed when starting container: %v", errPfx, err)
 	}
-	return nil
+
+	return instance, status.Errorf(codes.Internal, "%s; yet, restoration of previous state succeeded", errPfx)
 }
 
 func (m *Manager) performContainerUpdatePrechecks(ctx context.Context, instance, imageName, tag, cmd string, async bool, opts ...options.Option) ([]types.Container, error) {