FAQs and known issues

Do I need to change the way I use Docker when Enhanced Container Isolation is enabled?

No, you can continue to use Docker as usual. Enhanced Container Isolation will be mostly transparent to you.

Do all container workloads work well with Enhanced Container Isolation?

Most container workloads do, a few do not (yet). For the few workloads that don’t yet work with Enhanced Container Isolation, Docker will continue to improve the feature to reduce this to a minimum.

Can I run privileged containers with Enhanced Container Isolation?

Yes, you can use the --privileged flag in containers but unlike privileged containers without Enhanced Container Isolation, the container can only use it’s elevated privileges to access resources assigned to the container. It can’t access global kernel resources in the Docker Desktop Linux VM. This allows you to run privileged containers securely. For more information, see Key features and benefits.

Will all privileged container workloads run with Enhanced Container Isolation?

No. Privileged container workloads, or non-namespaced workloads, that wish to access global kernel resources inside the Docker Desktop Linux VM won’t work. For example, you can’t use a privileged container to load a kernel module.

Why not just restrict usage of the --privileged flag?

Privileged containers are typically used to run advanced workloads in containers, for example Docker-in-Docker or Kubernetes-in-Docker, to perform kernel operations such as loading modules, or to access hardware devices.

Enhanced Container Isolation allows running advanced workloads, but denies the ability to perform kernel operations or access hardware devices.

Does Enhanced Container Isolation restrict bind mounts inside the container?

Yes, it restricts bind mounts of directories located in the Docker Desktop Linux VM into the container.

It does not restrict bind mounts of your host machine files into the container, as configured via Docker Desktop’s Settings > Resources > File Sharing.

Does Enhanced Container Isolation protect all containers launched with Docker Desktop?

It protects all containers launched by users via docker create and docker run. It does not yet protect Docker Desktop Kubernetes pods, Extension Containers, and Dev Environments.

Does Enhanced Container Isolation affect performance of containers?

Enhanced Container Isolation has very little impact on the performance of containers. The exception is for containers that perform lots of mount and umount system calls, as these are trapped and vetted by the Sysbox container runtime.

With Enhanced Container Isolation, can the user still override the --runtime flag from the CLI ?

No. With Enhanced Container Isolation enabled, Sysbox is locked as the default (and only) runtime for containers deployed by Docker Desktop users. If a user attempts to override the runtime (e.g., docker run --runtime=runc), this request is ignored and the container is created through the Sysbox runtime.

The reason runc is disallowed with Enhanced Container Isolation because it allows users to run as “true root” on the Docker Desktop Linux VM, thereby providing them with implicit control of the VM and the ability to modify the administrative configurations for Docker Desktop, for example.

How is ECI different from Docker Engine’s userns-remap mode?

See How does it work.

How is ECI different from Rootless Docker?

See How does it work

Incompatibility with Windows Subsystem for Linux (WSL)

Enhanced Container Isolation (ECI) does not currently work when Docker Desktop runs on Windows with WSL/WSL2. This is due to some limitations of the WSL/WSL2 Linux Kernel. As a result, to use Enhanced Container Isolation on Windows, you must configure Docker Desktop to use Hyper-V. This can be enforced using Admin Controls. For more information, see Settings Management.

Docker build and buildx has some restrictions

With ECI enabled, Docker build --network=host and Docker buildx entitlements (network.host, security.insecure) are not allowed. Builds that require these will not work properly.

Kubernetes pods are not yet protected

Kubernetes pods are not yet protected by ECI. A malicious or privileged pod can compromise the Docker Desktop Linux VM and bypass security controls. We expect to improve on this in future versions of Docker Desktop.

Extension Containers are not yet protected

Extension containers are also not yet protected by ECI. Ensure you extension containers come from trusted entities to avoid issues. We expect to improve on this in future versions of Docker Desktop.

Docker Desktop dev environments are not yet protected

Containers launched by the Docker Desktop Dev Environments feature are not yet protected either. We expect to improve on this in future versions of Docker Desktop.

Use in production

In general users should not experience differences between running a container in Docker Desktop with ECI enabled, which uses the Sysbox runtime, and running that same container in production, through the standard OCI runc runtime.

However in some cases, typically when running advanced or privileged workloads in containers, users may experience some differences. In particular, the container may run with ECI but not with runc, or vice-versa.