Is it possible to run a Podman Machine from a docker container?

[stefanos-kalantzis]

I'm using quay.io/podman/stable:v4.2.1, and running it with docker run --privileged.

Inside the container, I also installed qemu with dnf install qemu.

$ podman machine init                                                                                                                                                                       
Downloading VM image: fedora-coreos-36.20221030.2.1-qemu.x86_64.qcow2.xz: done                                                                                                                                      
Extracting compressed file                                                                                                                                                                                          
Image resized.                                                                                                                                                                                                      
Error: exit status 1

$ podman machine start

Starting machine "podman-machine-default"
Waiting for VM ...
Error: qemu exited unexpectedly with exit code 1, stderr: qemu-system-x86_64: -fw_cfg name=opt/com.coreos/config,file=/home/jenkins/.config/containers/podman/machine/qemu/podman-machine-default.ign: can't load /home/jenkins/.config/containers/podman/machine/qemu/podman-machine-default.ign: Failed to open file “/home/jenkins/.config/containers/podman/machine/qemu/podman-machine-default.ign”: No such file or directory

Of course I didn't expect podman machine start to run, after the init failed with exit code 1. But there's no info there for why it failed.

Is what I'm trying to do a completely unsupported use-case?

---

More info in case it's relevant

$ podman info
WARN[0000] "/" is not a shared mount, this could cause issues or missing mounts with rootless containers
host:
  arch: amd64
  buildahVersion: 1.27.0
  cgroupControllers: []
  cgroupManager: cgroupfs
  cgroupVersion: v2
  conmon:
    package: conmon-2.1.4-3.fc36.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.4, commit: '
  cpuUtilization:
    idlePercent: 96.7
    systemPercent: 1.23
    userPercent: 2.07
  cpus: 16
  distribution:
    distribution: fedora
    variant: container
    version: "36"
  eventLogger: file
  hostname: e49b54ecef32
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1001
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1001
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 5.18.16-100.fc35.x86_64
  linkmode: dynamic
  logDriver: k8s-file
  memFree: 1985507328
  memTotal: 29159841792
  networkBackend: netavark
  ociRuntime:
    name: crun
    package: crun-1.6-2.fc36.x86_64
    path: /usr/bin/crun
    version: |-
      crun version 1.6
      commit: 18cf2efbb8feb2b2f20e316520e0fd0b6c41ef4d
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  remoteSocket:
    path: /tmp/podman-run-1001/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /usr/share/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.2.0-0.2.beta.0.fc36.x86_64
    version: |-
      slirp4netns version 1.2.0-beta.0
      commit: 477db14a24ff1a3de3a705e51ca2c4c1fe3dda64
      libslirp: 4.6.1
      SLIRP_CONFIG_VERSION_MAX: 3
      libseccomp: 2.5.3
  swapFree: 8470130688
  swapTotal: 8589930496
  uptime: 6h 13m 42.00s (Approximately 0.25 days)
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  volume:
  - local
registries:
  search:
  - registry.fedoraproject.org
  - registry.access.redhat.com
  - docker.io
  - quay.io
store:
  configFile: /home/jenkins/.config/containers/storage.conf
  containerStore:
    number: 0
    paused: 0
    running: 0
    stopped: 0
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/jenkins/.local/share/containers/storage
  graphRootAllocated: 628055080960
  graphRootUsed: 280718344192
  graphStatus:
    Backing Filesystem: btrfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 0
  runRoot: /tmp/podman-run-1001/containers
  volumePath: /home/jenkins/.local/share/containers/storage/volumes
version:
  APIVersion: 4.2.1
  Built: 1662580699
  BuiltTime: Wed Sep  7 19:58:19 2022
  GitCommit: ""
  GoVersion: go1.18.5
  Os: linux
  OsArch: linux/amd64
  Version: 4.2.1

[mheon]

I don't think we've ever considered anyone doing this. I'm leaning towards unsupported, but @baude probably has a stronger opinion than me.

[rhatdan]

You would need to leak /dev/kvm into the Docker command, to have any hope for this to work.

Theoretically it would work but you probably need to turn off a lot of security.