Merge ~bryce/ubuntu/+source/net-snmp:sru-lp2007856-lunar into ubuntu/+source/net-snmp:ubuntu/lunar-devel

After discussion with the reporter we'll not pursue SRU at this time, so for now the fix will just be this lunar MP.

I didn't quite understand what the patch is doing. Let's say a system has a mix of overlay and non-overlay filesystems, what is the current behaviour? No disk/storage info at all is returned by snmpd, or it just ignores the overlay ones but shows the rest?

For example, on a kubernetes host, I have quite a lot of overlay mounts (lines truncated for readability):

$ mount -t overlay
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...
overlay on /var/snap/microk8s/.../rootfs type overlay (rw,relatime,lowerdir=/var/...

These don't show up in the `df -h` output. Do you know if these would be in the snmpwalk output?

From looking at the code, currently mounts of type overlay are ignored (return NETSNMP_FS_TYPE_IGNORE). This patch adds 'overlay' to the '*other_fs' list, which is used to recognize certain filesystems like fuse, reiserfs, xfs, zfs, etc. that aren't recognized as "regular" filesystem types like ext*, vfat, and smbfs. I'm not entirely sure why net-snmp makes this distinction, but in any case this causes overlay mount points to not be ignored. So yes, I believe with this patch, your snmpwalk output would include listing those mount points.

It's still not clear, and I wasn't ready to run the docker container attached to the bug, so I added a comment there asking for clarification on what exactly is broken/not working without the patch.

Ok, got a reply in the bug, and did some tests.

The most notably change in behavior someone would see after applying this update would be if they were using the includeAllDisks snmpd.conf directive. Then all of a sudden if the host had overlayfs mounts, they would be included.

For lunar +1, maybe we need an FFe though.

Approvers: bryce, ahasenack
Uploaders: bryce, ahasenack
MP auto-approved

Thanks Andreas,

Given this is a simple change, and fixes a regression since bionic, an FFe may not be strictly necessary, but I've filed one anyway, LP: #2015828, just in case.

The FFe was approved, and I've uploaded it:

Successfully signed dsc, buildinfo, changes files
Vcs-Git: https://git.launchpad.net/~bryce/ubuntu/+source/net-snmp
Vcs-Git-Commit: bf2590820dd45fd4acaf75d5cf14c836a849f614
Vcs-Git-Ref: refs/heads/sru-lp2007856-lunar

$ dput ubuntu ../net-snmp_5.9.3+dfsg-2ubuntu3_source.changes
gpg: ../net-snmp_5.9.3+dfsg-2ubuntu3_source.changes: Valid signature from E603B2578FB8F0FB
gpg: ../net-snmp_5.9.3+dfsg-2ubuntu3.dsc: Valid signature from E603B2578FB8F0FB
D: Setting host argument.
Checking signature on .changes
Checking signature on .dsc
Uploading to ubuntu (via ftp to upload.ubuntu.com):
  Uploading net-snmp_5.9.3+dfsg-2ubuntu3.dsc: done.
  Uploading net-snmp_5.9.3+dfsg-2ubuntu3.debian.tar.xz: done.
  Uploading net-snmp_5.9.3+dfsg-2ubuntu3_source.buildinfo: done.
  Uploading net-snmp_5.9.3+dfsg-2ubuntu3_source.changes: done.
Successfully uploaded packages.

I also added an entry to the release notes, as graham suggested:

https://discourse.ubuntu.com/t/lunar-lobster-release-notes/31910