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?

The great majority of container workloads run fine with ECI, but 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 (including Docker-in-Docker). For more information, see Key features and benefits.

Will all privileged container workloads run with Enhanced Container Isolation?

No. Privileged container 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 protect container launched prior to enabling ECI?

No. Containers created prior to enabling ECI are not protected. Therefore, we recommend removing all containers prior to enabling ECI. In the future Docker Desktop will likely make this a hard requirement.

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 to ensure they are not being used to breach the container’s filesystem.

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

No. With Enhanced Container Isolation enabled, Sysbox is set 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

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