Chapter 5. Containers

The system connections and farm information stored in the containers.conf file are now read-only

• The system connections and farm information stored in the containers.conf file are now read-only. The system connections and farm information will now be stored in the podman.connections.json file, managed only by Podman. Podman continues to support the old configuration options such as [engine.service_destinations] and the [farms] section. You can still add connections or farms manually if needed; however, it is not possible to delete a connection from the containers.conf file with the podman system connection rm command.

The slirp4netns network mode is deprecated

• The slirp4netns network mode is deprecated and will be removed in a future major release of RHEL. The pasta network mode is the default network mode for rootless containers.

The cgroups v1 for rootless containers is deprecated

• The cgroups v1 for rootless containers is deprecated and will be removed in a future major release of RHEL. The cgroups v2 is used by default instead of cgroups v1.

The containernetworking-plugins package and the CNI network stack are no longer supported

• The containernetworking-plugins package is removed, and the CNI network stack is no longer supported.

  • If you upgrade from the previous RHEL versions to RHEL 10.0 or if you have a fresh installation of RHEL 10.0, the CNI network backend is no longer available. Existing containers that use CNI for networking will no longer function and will need to be removed and recreated. Newly created containers will use the default netavark network backend.
  • If present, the cni value in the containers.conf file for the network_backend option must be changed to netavark or can be unset.

• OverlayFS as the kernel interface
• Enhanced Read-Only File System (EROFS) for a mountable metadata tree
• The fs-verity feature (optional) from the lower filesystem

• Separation between metadata and data. composefs does not store any persistent data. The underlying metadata and data files are stored in a valid lower Linux filesystem such as ext4, xfs, and so on.
• Mounting multiple composefs with a shared storage.
• Data files are shared in the page cache to enable multiple container images to share their memory.
• Support fs-verity validation of the content files.