in_unix plugin does not work with --under-supervisor (permission denied with var/run/fluent/fluent.sock)

[sijin-won]

Describe the bug

We run fluentd without any the command line option(automatically with --under-supervisor). the in_unix plugin didn't work because the socket file's permission was insufficient.

$ ls -l /var/run/fluent/fluent.sock
srwxr-xr-x 1 _fluentd _fluentd 0 Oct 26 08:27 /var/run/fluent/fluent.sock

To Reproduce

1. Install fluent with the following command

# fluent-package 5 (LTS)
curl -fsSL https://toolbelt.treasuredata.com/sh/install-ubuntu-jammy-fluent-package5-lts.sh | sh

2. add configuration

<source>
  @type unix
  path /var/run/fluent/fluent.sock
</source>

3. restart fluentd with the following command

$ sudo systemctl restart fluentd.service

4. The created /var/run/fluent/fluent.sock file can not be written

$ ls -l /var/run/fluent/fluent.sock
srwxr-xr-x 1 _fluentd _fluentd 0 Oct 26 08:27 /var/run/fluent/fluent.sock

Expected behavior

The permission should be srwxrwxrwx.

Your Environment

- Fluentd version:

$ sudo fluent-gem list | grep fluentd
fluentd (1.16.2)

• TD Agent version:
• Operating system:

$ cat /etc/os-release
PRETTY_NAME="Ubuntu 22.04.3 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.3 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy

• Kernel version:

$ uname -r
6.2.0-1017-gcp

Your Configuration

<source>
  @type unix
  path /var/run/fluent/fluent.sock
</source>

Your Error Log

nothing

Additional context

No response

[ashie]

Expected behavior

The permission should be srwxrwxrwx.

Hmm, it should be customizable.