You have been subscribed to a public bug:
If i launch a new cloud instance, and then ssh to it, my ssh login
blocks, stopping me from doing useful work while '/usr/lib/update-
notifier/apt-check' runs.
By far, the biggest offender of this slow login is
/usr/lib/update-notifier/apt-check.
To demonstrate, a fresh cloud instance on azure.
## ssh to the instance and run a non-interactive command:
$ time ssh $cloudhost /bin/true
real 0m5.066s
user 0m0.045s
sys 0m0.004s
## ssh in and disable updates-available so it wont run at all
$ ssh $cloudhost sudo chmod -x /etc/update-motd.d/90-updates-available
$ time ssh $cloudhost /bin/true
real 0m2.459s
user 0m0.026s
sys 0m0.015s
## so disabling that bought us 2.5 seconds back.
## How about entirely disabling update-motd
$ ssh $cloudhost "sudo cp /etc/pam.d/sshd /etc/pam.d/sshd.dist"
$ ssh $cloudhost "sudo sed -i '/^[^#].*pam_motd/s/^/#/' /etc/pam.d/sshd"
$ time ssh $cloudhost /bin/true
real 0m0.650s
user 0m0.041s
sys 0m0.004s
Note, that these things happen even for non-interactive logins, where
the message of the day is completely swallowed. Automation tools suffer
this ever time they ssh to a ubuntu system.
ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: update-notifier-common 3.157
ProcVersionSignature: User Name 3.16.0-30.40-generic 3.16.7-ckt3
Uname: Linux 3.16.0-30-generic x86_64
ApportVersion: 2.14.7-0ubuntu8.2
Architecture: amd64
Date: Thu Feb 26 16:27:02 2015
PackageArchitecture: all
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: update-notifier
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: openssh (Ubuntu)
Importance: Undecided
Status: New
** Affects: update-notifier (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug uec-images utopic
--
apt-check should not be run from update-motd
https://bugs.launchpad.net/bugs/1426023
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