Should push output be sent to "stderr" instead of "stdout" ?

[leadoflife]

Currently, podman push ... is executing successfully while sending output to "stderr" and not "stdout" while ending with a zero exit code.

I also confirmed that both successful and failed commands both use "stderr" for output.

Is this a bug or a feature? I know other tools, like the infamous java -version used to output to "stderr" until the provided alternatives that properly use "stdout".

podman info

host:
  arch: amd64
  buildahVersion: 1.30.0
  cgroupControllers: []
  cgroupManager: cgroupfs
  cgroupVersion: v1
  conmon:
    package: conmon-2.1.7-2.fc37.x86_64
    path: /usr/bin/conmon
    version: 'conmon version 2.1.7, commit: '
  cpuUtilization:
    idlePercent: 99.93
    systemPercent: 0.03
    userPercent: 0.03
  cpus: 16
  databaseBackend: boltdb
  distribution:
    distribution: fedora
    variant: container
    version: "37"
  eventLogger: journald
  hostname: LAPTOP-E4NFDVCK
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 524288
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1000
      size: 1
    - container_id: 1
      host_id: 524288
      size: 65536
  kernel: 5.15.90.1-microsoft-standard-WSL2
  linkmode: dynamic
  logDriver: journald
  memFree: 12354293760
  memTotal: 16773308416
  networkBackend: netavark
  ociRuntime:
    name: crun
    package: crun-1.8.5-1.fc37.x86_64
    path: /usr/bin/crun
    version: |-
      crun version 1.8.5
      commit: b6f80f766c9a89eb7b1440c0a70ab287434b17ed
      rundir: /run/user/1000/crun
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +LIBKRUN +WASM:wasmedge +YAJL
  os: linux
  remoteSocket:
    exists: true
    path: /run/user/1000/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: true
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: slirp4netns-1.2.0-8.fc37.x86_64
    version: |-
      slirp4netns version 1.2.0
      commit: 656041d45cfca7a4176f6b7eed9e4fe6c11e8383
      libslirp: 4.7.0
      SLIRP_CONFIG_VERSION_MAX: 4
      libseccomp: 2.5.3
  swapFree: 4294967296
  swapTotal: 4294967296
  uptime: 26h 9m 31.00s (Approximately 1.08 days)
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  - ipvlan
  volume:
  - local
registries:
  search:
  - docker.io
store:
  configFile: /home/user/.config/containers/storage.conf
  containerStore:
    number: 1
    paused: 0
    running: 1
    stopped: 0
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/user/.local/share/containers/storage
  graphRootAllocated: 1081101176832
  graphRootUsed: 14233845760
  graphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 626
  runRoot: /run/user/1000/containers
  transientStore: false
  volumePath: /home/user/.local/share/containers/storage/volumes
version:
  APIVersion: 4.5.0
  Built: 1681486976
  BuiltTime: Fri Apr 14 11:42:56 2023
  GitCommit: ""
  GoVersion: go1.19.7
  Os: linux
  OsArch: linux/amd64
  Version: 4.5.0

[vrothberg]

Thanks for reaching out, @leadoflife.

I have no recollection on this decision but assume some history behind it.

@baude @mtrmac @rhatdan do you?

[Luap99]

Progress messages are commonly send on stderr.
It is not so important for push but for things like pull you can do:

id=$(podman pull myimage)
podman run $id ...

[rhatdan]

Right the important thing is for pull, but for consistency it makes sense for both to be sent to stderr. I would recommend against changing.

[mtrmac]

A git blame expedition points, after a few waypoints, at #362 , which requires us to use stderr for podman save, not necessarily for podman pull; though the consistency is certainly attractive.