PBS: proxmox-backup-proxy fails to start due to permission issues on /run/proxmox-backup

STRUBartacus

Active Member
Apr 15, 2018
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Hello,

after an update around two weeks ago, one of our Proxmox Backup Server instances stopped starting the service

proxmox-backup-proxy.service

Problem:

The service fails with permission errors related to the runtime directory:

mkstemp "/run/proxmox-backup/proxy.tmp_XXXXXX" failed: EACCES: Permission denied

As a result, proxmox-backup-proxy cannot create temporary files in

/run/proxmox-backup

and does not start correctly.

This PBS is running inside an LXC container.
Another PBS LXC with the same version and similar configuration is not affected.


Observed behavior:

- proxmox-backup-proxy runs as user "backup"
- There are permission issues on /run/proxmox-backup
- The proxy fails to start due to missing write access
- Removing and recreating the directory manually fixes the issue immediately


Manual workaround:

install -d -m 0755 -o backup -g backup /run/proxmox-backup
systemctl restart proxmox-backup-proxy


Permanent workaround:

To make the fix persistent, we added a systemd drop-in for the parent service
"proxmox-backup":

[Service]
ExecStartPre=/usr/bin/install -d -m 0755 -o backup -g backup /run/proxmox-backup

Since then, the proxy starts reliably, including after reboot.


Summary:

- After an update, proxmox-backup-proxy fails to start
- Cause is a permission problem on /run/proxmox-backup
- Manually creating the directory with correct permissions resolves the issue
- A systemd ExecStartPre workaround ensures reliable startup


Has anyone else observed similar behavior, or is there an official or recommended
way PBS should handle creation of /run/proxmox-backup?