CentOS - Oct 2020 - SEcontext setting failure on an external harddisk

I tried moving a PosgreSQL database to an external harddisk due to lack of space
on the main harddisks. Not the ideal solution of course but it should work.
However, on CentOS 7 the external harddisk is mounted under /run/media and the
user. I copied the postgresql database directory and made sure it is owned
recursively by postgres, changed the necessary settings in both the systemd unit
and the conf file.

After that, updating the selinux contexts is required but that fails on the
external disk due to a conflict which I understand is due it is under /run/media
and the user. semanage fcontext kicked back an error message suggesting I try
setting it for /var/run/media etc instead which works but restorecon -Rv for
that directory fails to set the context which I can check with ls -lZ.

Does anyone know how I can get around this? Is there an inherent conflict
because it is mounted under a specific user despite the postgresql directory is
owned by postgres? If so, should I mount it under eg /opt/ instead? Would that
make a difference?

Or, can I "force" a new context on the postgres directory tree some
other way?

Thanks!

On Oct 8, 2020, at 15:22, H <agents at meddatainc.com>
wrote:
> 
> ?I tried moving a PosgreSQL database to an external harddisk due to lack of
space on the main harddisks. Not the ideal solution of course but it should
work. However, on CentOS 7 the external harddisk is mounted under /run/media and
the user. I copied the postgresql database directory and made sure it is owned
recursively by postgres, changed the necessary settings in both the systemd unit
and the conf file.
I don?t believe that the volume will be mounted on boot in /run/media, that is
for storage mounted by a user logged at the console.

It would make more sense to set up a systemd .mount and .automount unit for the
device and mount point (someplace outside of /run, such as /srv/mountpointname).
Then set up the labels correctly.

You need to use a file system that supports extended attribute if you want it to
work with selinux, so XFS or ext4.

--
Jonathan Billings

On 10/08/2020 11:10 PM, Jonathan Billings wrote:
> On Oct 8, 2020, at 15:22, H <agents at meddatainc.com> wrote:
>> ?I tried moving a PosgreSQL database to an external harddisk due to
lack of space on the main harddisks. Not the ideal solution of course but it
should work. However, on CentOS 7 the external harddisk is mounted under
/run/media and the user. I copied the postgresql database directory and made
sure it is owned recursively by postgres, changed the necessary settings in both
the systemd unit and the conf file.
> I don?t believe that the volume will be mounted on boot in /run/media, that
is for storage mounted by a user logged at the console.
>
> It would make more sense to set up a systemd .mount and .automount unit for
the device and mount point (someplace outside of /run, such as
/srv/mountpointname). Then set up the labels correctly.
>
> You need to use a file system that supports extended attribute if you want
it to work with selinux, so XFS or ext4.
>
> --
> Jonathan Billings
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
You are correct, I mounted the external harddisk as a user. The harddisk is
formatted xfs so it supports labels.

However, I was not planning to automount this disk every time which of course
would mean postgresql would fail without the harddisk. It might be better to use
the smaller existing space on the existing harddisk until I buy a larger
internal harddisk which would automount and then move postgresql to that.

Thank you for your reply.