Creation of healthcheck service fails in rootless mode

[stefanb2]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

Adding --healthcheck-command XXX in rootless mode results in a warning instead of creation of the service & timer units.

Steps to reproduce the issue:

$ podman run --rm -it --name fedora --healthcheck-command /bin/true fedora /bin/bash

Describe the results you received:

$ id
uid=1000(stefanb) gid=1000(stefanb) groups=1000(stefanb),39(video),970(wireshark) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

$ podman run --rm -it --name fedora --healthcheck-command /bin/true fedora /bin/bash
ERRO[0000] unable to get systemd connection to add healthchecks: read unix @->/run/systemd/private: read: connection reset by peer 
ERRO[0000] unable to get systemd connection to start healthchecks: read unix @->/run/systemd/private: read: connection reset by peer 

$ podman container inspect --format='{{json .Config.Healthcheck}}' fedora
{"Test":["/bin/true"],"Interval":30000000000,"Timeout":30000000000,"Retries":3}

# after one or more intervals have passed...
$ podman container inspect --format='{{json .State.Healthcheck}}' fedora
{"Status":"starting","FailingStreak":0,"Log":null}

$ ls -lhtZ /run/systemd/private
srwxrwxrwx. 1 root root system_u:object_r:init_var_run_t:s0 0  7. 7. 18:21 /run/systemd/private

# exiting the container...
[root@5fb996f9ed4d /]# exit
ERRO[1169] Error removing timer for container 5fb996f9ed4de0b618c273b91cfc2fa3de59d992bcaf8d2325709165fc8a054c healthcheck: unable to get systemd connection to remove healthchecks: read unix @->/run/systemd/private: read: connection reset by peer 

Describe the results you expected:

Service & timer should be generated

Additional information you deem important (e.g. issue happens only occasionally):

I guess the error means that podman tries the equivalent of systemctl --system instead of systemctl --user:

$ ls -lhtZ /run/user/$(id -u)/systemd/private
srwxr-xr-x. 1 stefanb stefanb unconfined_u:object_r:user_tmp_t:s0 0  7. 7. 18:21 /run/user/1000/systemd/private

Output of podman version:

Version:            1.4.5-dev
RemoteAPI Version:  1
Go Version:         go1.12.6
OS/Arch:            linux/amd64

Output of podman info --debug:

debug:
  compiler: gc
  git commit: ""
  go version: go1.12.6
  podman version: 1.4.5-dev
host:
  BuildahVersion: 1.9.0
  Conmon:
    package: podman-1.4.4-1.fc30.x86_64
    path: /usr/libexec/podman/conmon
    version: 'conmon version 0.2.0, commit: 41010e63c287618b1dc34ee11d10d268e2feeefe'
  Distribution:
    distribution: fedora
    version: "30"
  MemFree: 18336714752
  MemTotal: 33400737792
  OCIRuntime:
    package: runc-1.0.0-93.dev.gitb9b6cc6.fc30.x86_64
    path: /usr/bin/runc
    version: |-
      runc version 1.0.0-rc8+dev
      commit: e3b4c1108f7d1bf0d09ab612ea09927d9b59b4e3
      spec: 1.0.1-dev
  SwapFree: 32002535424
  SwapTotal: 32002535424
  arch: amd64
  cpus: 12
  hostname: beckst-lnx
  kernel: 5.1.16-300.fc30.x86_64
  os: linux
  rootless: true
  uptime: 38h 0m 19.43s (Approximately 1.58 days)
registries:
  blocked: null
  insecure: null
  search:
  - docker.io
  - registry.fedoraproject.org
  - quay.io
  - registry.access.redhat.com
  - registry.centos.org
store:
  ConfigFile: /home/stefanb/.config/containers/storage.conf
  ContainerStore:
    number: 1
  GraphDriverName: overlay
  GraphOptions:
  - overlay.mount_program=/usr/bin/fuse-overlayfs
  GraphRoot: /home/stefanb/.local/share/containers/storage
  GraphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "false"
    Supports d_type: "true"
    Using metacopy: "false"
  ImageStore:
    number: 7
  RunRoot: /tmp/1000
  VolumePath: /home/stefanb/.local/share/containers/storage/volumes

[giuseppe]

PR here: #3529