[Bug 2057768] Re: Unit and its Alias appear to be separate entities when enabling the unit by filepath

[Nick Rosbrook]

** Also affects: systemd (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Also affects: systemd (Ubuntu Jammy)
   Importance: Undecided
       Status: New

** Also affects: systemd (Ubuntu Mantic)
   Importance: Undecided
       Status: New

** Changed in: systemd (Ubuntu Mantic)
       Status: New => Won't Fix

** Changed in: systemd (Ubuntu Focal)
       Status: New => Confirmed

** Changed in: systemd (Ubuntu Jammy)
       Status: New => Confirmed

** Changed in: systemd (Ubuntu Focal)
   Importance: Undecided => Wishlist

** Changed in: systemd (Ubuntu Jammy)
   Importance: Undecided => Wishlist

** Changed in: systemd (Ubuntu)
   Importance: Wishlist => Medium

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https://bugs.launchpad.net/bugs/2057768

Title:
  Unit and its Alias appear to be separate entities when enabling the
  unit by filepath

Status in systemd package in Ubuntu:
  Triaged
Status in systemd source package in Focal:
  Confirmed
Status in systemd source package in Jammy:
  Confirmed
Status in systemd source package in Mantic:
  Won't Fix

Bug description:
  ### systemd version the issue has been seen with

  245

  ### Used distribution

  Linux Mint 20.1 and Ubuntu 20.04

  ### Linux kernel version used

  5.4.0-135-generic

  ### CPU architectures issue was seen on

  None

  ### Component

  systemctl

  ### Expected behaviour you didn't see

  When including an alias in a unit file that is enabled by referring to
  its filepath, its alias should refer to the unit - the two should refer
  to the exact same service. This is the case when the unit file is
  enabled inside one of the systemd directories. I expect alias and unit
  to refer to one identical service also when enabling via filepath.

  In particular, the output of  `systemctl status ...` should be identical
  for a Unit and its Alias.

  ### Unexpected behaviour you saw

  After passing a systemd unit including an alias to `systemctl enable
  PATH...` by path, systemctl treated the unit and its alias as separate
  units.

  Specifically, `systemctl status` reports different results
  (running/inactive, PID if applicable) for the unit name and its alias.
  When I start the unit by its original name, only the status of the unit
  is reported as running while the status of the alias remains inactive,
  and vice versa. After starting the Alias too, two services with
  different PIDs are running.

  (When copying the unit into /etc/systemd/system/ and running `systemctl
  enable UNIT...` this issue does not occur and alias and unit behave the
  same.)

  ### Steps to reproduce the problem

  ```
  ~$ cat dummy.service
  [Service]
  ExecStart=tail -f /dev/null

  [Install]
  Alias=dumb.service
  ~$ sudo systemctl enable ~/dummy.service
  Created symlink /etc/systemd/system/dumb.service →
  /home/lukas/dummy.service.
  Created symlink /etc/systemd/system/dummy.service →
  /home/lukas/dummy.service.
  ~$ sudo systemctl start dummy
  ~$ systemctl status dummy
  ● dummy.service
       Loaded: loaded (/etc/systemd/system/dummy.service; enabled; vendor
  preset:>
       Active: active (running) since Tue 2024-03-12 15:36:58 CET; 8s ago
     Main PID: 159809 (tail)
        Tasks: 1 (limit: 76978)
       Memory: 160.0K
       CGroup: /system.slice/dummy.service
               └─159809 /usr/bin/tail -f /dev/null

  Mär 12 15:36:58 MyMachine systemd[1]: Started dummy.service.
  ~$ systemctl status dumb
  ● dumb.service
       Loaded: loaded (/etc/systemd/system/dumb.service; enabled; vendor
  preset: >
       Active: inactive (dead)

  Mär 12 15:30:53 MyMachine systemd[1]: Started dumb.service.
  Mär 12 15:31:16 MyMachine systemd[1]: Stopping dumb.service...
  Mär 12 15:31:16 MyMachine systemd[1]: dumb.service: Succeeded.
  Mär 12 15:31:16 MyMachine systemd[1]: Stopped dumb.service.
  ~$
  ```

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