Autoupdate should be less frequent and more randomly distributed

[Bret Barker]

Currently the autoupdate timer (snappy/debian/snappy-autopilot.timer) is set to hourly with a 15 minute accuracy.

As snappy will be included in 16.04 desktops (millions of them), this rate has the potential to seriously overload the Click Package Index service. I suggest changing this to 3 times per day, randomly distributed across 24hr on a per host basis so we don't get top-of-the hour thundering herds.

Further rationale is to also avoid having updates downloaded by all hosts within the first hour of release, since gradual/staged updates are not implemented for snaps.

[Bret Barker (noise)]

We are getting close to 16.04 release and really need this changed prior to that. Can someone please take a look at this?

[Michael Vogt (mvo)]

This is included in master: https://github.com/ubuntu-core/snappy/commit/7669466838dd1227068abc1a8bb363cd86333c50

[Michael Vogt (mvo)]

There is a regression here and we currently only randomize by 2h: https://github.com/snapcore/snapd/blob/master/debian/snapd.refresh.timer

We could change to what apt is doing: https://github.com/Debian/apt/blob/master/debian/apt-daily.timer or we could use the previous commit from John: https://github.com/ubuntu-core/snappy/commit/7669466838dd1227068abc1a8bb363cd86333c50

[Michael Vogt (mvo)]

As discussed on irc, we will revert back to https://github.com/ubuntu-core/snappy/commit/7669466838dd1227068abc1a8bb363cd86333c50 (4x day)

[Chris J Arges (arges)]

Hello Bret, or anyone else affected,

Accepted snapd into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/snapd/2.0.8 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Bret Barker (noise)]

Michael,

Just wanted to clarify one thing - will the 4x daily checks happen for every user of 16.04 desktop or only those that have installed at least 1 snap (and thus the core snap as well)?

[Federico Gimenez (fgimenez)]

Verified the randomness of the installed timer with snapd from proposed by checking the scheduled times in two consecutive installations:

fgimenez@fgimenez-Standard-PC-i440FX-PIIX-1996:~$ apt-cache policy snapd
snapd:
  Installed: 2.0.8
  Candidate: 2.0.8
  Version table:
 *** 2.0.8 500
        500 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     2.0.5 500
        500 http://es.archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
     2.0.2 500
        500 http://es.archive.ubuntu.com/ubuntu xenial/main amd64 Packages
fgimenez@fgimenez-Standard-PC-i440FX-PIIX-1996:~$ sudo systemctl status snapd.refresh.timer
● snapd.refresh.timer - Timer to automatically refresh installed snaps
   Loaded: loaded (/lib/systemd/system/snapd.refresh.timer; enabled; vendor preset: enabled)
   Active: active (waiting) since lun 2016-06-13 09:13:27 CEST; 9s ago

jun 13 09:13:27 fgimenez-Standard-PC-i440FX-PIIX-1996 systemd[1]: snapd.refresh.timer: Adding 1h 36min 19.904959s random time.
jun 13 09:13:27 fgimenez-Standard-PC-i440FX-PIIX-1996 systemd[1]: Started Timer to automatically refresh installed snaps.
jun 13 09:13:27 fgimenez-Standard-PC-i440FX-PIIX-1996 systemd[1]: snapd.refresh.timer: Adding 4h 41min 2.765543s random time.
jun 13 09:13:27 fgimenez-Standard-PC-i440FX-PIIX-1996 systemd[1]: snapd.refresh.timer: Adding 2h 22min 46.565780s random time.
fgimenez@fgimenez-Standard-PC-i440FX-PIIX-1996:~$ sudo apt-get remove --purge snapd
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.4.0-21 linux-headers-4.4.0-21-generic linux-image-4.4.0-21-generic linux-image-extra-4.4.0-21-generic
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  snapd*
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
After this operation, 22,1 MB disk space will be freed.
Do you want to continue? [Y/n]
(Reading database ... 244530 files and directories currently installed.)
Removing snapd (2.0.8) ...
Warning: Stopping snapd.service, but it can still be activated by:
  snapd.socket
Purging configuration files for snapd (2.0.8) ...
dpkg: warning: while removing snapd, directory '/snap' not empty so not removed
dpkg: warning: while removing snapd, directory '/var/snap' not empty so not removed
dpkg: warning: while removing snapd, directory '/var/lib/snapd/snaps' not empty so not removed
dpkg: warning: while removing snapd, directory '/var/lib/snapd/desktop' not empty so not removed
Processing triggers for man-db (2.7.5-1) ...
fgimenez@fgimenez-Standard-PC-i440FX-PIIX-1996:~$ sudo apt-get install snapd
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.4.0-21 linux-headers-4.4.0-21-generic linux-image-4.4.0-21-generic linux-image-extra-4.4.0-21-generic
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  snapd
0 upgraded, 1 newly installed, 0 to remove and 0 not up...

[Launchpad Janitor (janitor)]

This bug was fixed in the package snapd - 2.0.8

---------------
snapd (2.0.8) xenial; urgency=medium

  * New upstream release: LP: #1589534
    - debian: make `snap refresh` times more random (LP: #1537793)
    - cmd: ExecInCoreSnap looks in "core" snap first, and only in
      "ubuntu-core" snap if rev>125.
    - cmd/snap: have 'snap list' display helper message on stderr
      (LP: #1587445)
    - snap: make app names more restrictive.

 -- Michael Vogt <email address hidden> Wed, 08 Jun 2016 07:56:58 +0200

[Steve Langasek (vorlon)]

The verification of the Stable Release Update for snapd has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.