Podman

Podman can run rootless containers and be a drop-in replacement for Docker.

Install and configure podman with NixOS service configuration

{ pkgs, ... }:
{
  virtualisation = {
    podman = {
      enable = true;

      # Create a `docker` alias for podman, to use it as a drop-in replacement
      dockerCompat = true;

      # Required for containers under podman-compose to be able to talk to each other.
      virtualisation.podman.defaultNetwork.dnsname.enable      
      # For Nixos version > 22.11
      #defaultNetwork.settings = {
      #  dns_enabled = true;
      #};
    };
  };
}

podman-compose

podman-compose is a drop-in replacement for docker-compose

Using podman with ZFS

For root using ZFS, podman needs access to the ZFS tools.

virtualisation.podman.extraPackages = [ pkgs.zfs ];

Rootless can't use ZFS directly but the overlay needs POSIX ACL enabled for the underlying ZFS filesystem, ie., acltype=posixacl

Best to mount a dataset under /var/lib/containers/storage with property acltype=posixacl.

Use Podman within nix-shell

https://gist.github.com/adisbladis/187204cb772800489ee3dac4acdd9947

Note that rootless podman requires newuidmap (from shadow). If you're not on NixOS, this cannot be supplied by the Nix package 'shadow' since setuid/setgid programs are not currently supported by Nix.

Run Podman containers as systemd services

{
  virtualisation.oci-containers.backend = "podman";
  virtualisation.oci-containers.containers = {
    container-name = {
      image = "container-image";
      autoStart = true;
      ports = [ "127.0.0.1:1234:1234" ];
    };
  };
}