Merge ~ahasenack/ubuntu/+source/nfs-utils:groovy-nfs-utils-restart-1928259 into ubuntu/+source/nfs-utils:ubuntu/groovy-devel

[Andreas Hasenack]

PPA: https://launchpad.net/~ahasenack/+archive/ubuntu/nfs-utils-restart-1928259

sudo add-apt-repository ppa:ahasenack/nfs-utils-restart-1928259

To test, follow the testing procedure in the linked bug, or, for a more detailed test, the SRU bug #1927745 and confirm that rpc.gssd was restarted after the package upgrade (different pid).

This is an attempt to fix the linked bug in the less intrusive way possible, because I want to use the same fix for an SRU all the way back to bionic.

The goal of this fix is to mark nfs-utils.service as "started", so that the debhelper postinst section will correctly restart it on upgrade.

Key aspects of this fix:
- nfs-utils.service is a "fake" service meant to control other units that declare PartOf=nfs-utils.service. It's ExecStart is simply /bin/true. There is also no [Install] section, so it can't be enabled as-is
- PartOf only has effect on "stop" and "restart":
"""
PartOf=
  Configures dependencies similar to Requires=, but limited to stopping and restarting of units. When systemd stops or restarts the units listed here, the action is propagated to this unit. Note that this is a one-way dependency — changes to this unit do not affect the listed units.
"""

This last bit is kind of crucial: it means that the "start" action has no effect on units linked via PartOf. It will just mark nfs-utils.service itself as being started (and it only runs /bin/true).

I tested this in some scenarios to make sure that the "start" action isn't starting anything by itself, and that remains true as far as I can see. The only thing that is flagged as started is nfs-utils.service itself, but just because of its RemainAfterExit=yes.

I also tested this when one of the services declaring PartOf=nfs-utils.service was masked or disabled, and it worked as expected. In both cases (masked or disabled) the service didn't start.

Another test I did was if nfs-utils.service was masked. In that case, the postinst complained about it, didn't error, and no dependent services were restarted at the end of the package upgrade, which is what I expected.

Still, this is probably not the way upstream intended for this to work (these systemd service files come from upstream, and Debian and Fedora are also affected by this bug). But a bigger surgery on all these systemd service files is out of scope for the SRU.

[Christian Ehrhardt  (paelzer)]

As outlined in the Hirsute MP (https://code.launchpad.net/~ahasenack/ubuntu/+source/nfs-utils/+git/nfs-utils/+merge/403835/comments/1064578) +1 to this approach and presented MP.

review: Approve

[Andreas Hasenack (ahasenack)]

Thanks, tagging (with the right SRU version) and uploading

Had to delete the existing upload tag upload/1%1.3.4-2.5ubuntu6.1 from a failed SRU

09:32 $ head -n 1 debian/changelog ; git ubuntu tag --upload; git describe HEAD
nfs-utils (1:1.3.4-2.5ubuntu6.1) groovy; urgency=medium
upload/1%1.3.4-2.5ubuntu6.1
✔ ~/git/packages/nfs-utils/nfs-utils [groovy-nfs-utils-restart-1928259 ↑·3|✔]
09:32 $ git push pkg upload/1%1.3.4-2.5ubuntu6.1 --force
Enumerating objects: 17, done.
Counting objects: 100% (17/17), done.
Delta compression using up to 4 threads
Compressing objects: 100% (13/13), done.
Writing objects: 100% (13/13), 1.56 KiB | 56.00 KiB/s, done.
Total 13 (delta 9), reused 0 (delta 0), pack-reused 0
To ssh://git.launchpad.net/~usd-import-team/ubuntu/+source/nfs-utils
 + 10e576c4...526556c9 upload/1%1.3.4-2.5ubuntu6.1 -> upload/1%1.3.4-2.5ubuntu6.1 (forced update)

$ dput ubuntu ../nfs-utils_1.3.4-2.5ubuntu6.1_source.changes
Checking signature on .changes
gpg: ../nfs-utils_1.3.4-2.5ubuntu6.1_source.changes: Valid signature from AC983EB5BF6BCBA9
Checking signature on .dsc
gpg: ../nfs-utils_1.3.4-2.5ubuntu6.1.dsc: Valid signature from AC983EB5BF6BCBA9
Uploading to ubuntu (via ftp to upload.ubuntu.com):
  Uploading nfs-utils_1.3.4-2.5ubuntu6.1.dsc: done.
  Uploading nfs-utils_1.3.4-2.5ubuntu6.1.debian.tar.xz: done.
  Uploading nfs-utils_1.3.4-2.5ubuntu6.1_source.buildinfo: done.
  Uploading nfs-utils_1.3.4-2.5ubuntu6.1_source.changes: done.
Successfully uploaded packages.

diff --git a/debian/changelog b/debian/changelog
index 49e85c3..b790991 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,10 @@
+nfs-utils (1:1.3.4-2.5ubuntu6.1) groovy; urgency=medium
+
+  * d/nfs-common.postinst: always start nfs-utils.service, so the restart in
+    the #DEBHELPER# section can do its job if needed (LP: #1928259)
+
+ -- Andreas Hasenack <[e-mail]>  Mon, 24 May 2021 17:55:01 -0300
+
 nfs-utils (1:1.3.4-2.5ubuntu6) groovy; urgency=medium
 
   * Allow compilation to succeed with -fno-common (Closes: #957608)
diff --git a/debian/nfs-common.postinst b/debian/nfs-common.postinst
index 076b6b6..5b52b03 100644
--- a/debian/nfs-common.postinst
+++ b/debian/nfs-common.postinst
@@ -43,6 +43,10 @@ case "$1" in
 	if [ -f /lib/init/rw/sendsigs.omit.d/statd ]; then 
 	    mv /lib/init/rw/sendsigs.omit.d/statd /run/sendsigs.omit.d/statd
 	fi
+
+        # always "start" nfs-utils.service, so package upgrades will restart it,
+        # see LP: #1928259
+        systemctl start nfs-utils.service > /dev/null || true
     ;;
 esac