[Bug 1738412] Re: Init script fails test on reload/restart because of faulty regex

Tue Oct 30 13:21:07 UTC 2018

** Description changed:

  [Impact]
  The squid initscript has a guard against configuration mistakes that prevents the service from being disrupted if the current config has an invalid setting.

  This guard relies on the "squid -k parse" command which analyzes the
  configuration and, in the case of a fatal problem, outputs the string
  "FATAL: <reason>". The initscript parses that output to catch such
  errors before further action is taken.

  There is a mistake in the expression that is looked for, though: instead
  of "FATAL: ", the initscript is looking for "FATAL " (i.e., no ":"). The
  consequence is that actions that would reload or restart the service end
  up shutting the service down in the case of a configuration error.

  The change fixes the expression that is looked for, restoring the
  functionality of the guard.

  [Test Case]
  * install squid:
  sudo apt update && sudo apt install squid -y

  * confirm the reload action is quick to return and doesn't change the pid of squid, i.e., it's not restarted:
  ubuntu at xenial-squid-reload-syntax:~$ pidof squid
  2684
  ubuntu at xenial-squid-reload-syntax:~$ sudo service squid reload
  ubuntu at xenial-squid-reload-syntax:~$ pidof squid
  2684
  ubuntu at xenial-squid-reload-syntax:~$

  * add an invalid setting to the config file:
  echo "acl nonsense nonsense nonsense" | sudo tee -a /etc/squid/squid.conf

  * reload squid one more time:
  sudo service squid reload

  * After about 30s, squid should be dead and service squid status should show errors:
  ubuntu at xenial-squid-reload-syntax:~$ pidof squid
  ubuntu at xenial-squid-reload-syntax:~$

  ubuntu at xenial-squid-reload-syntax:~$ sudo service squid status
  ● squid.service - LSB: Squid HTTP Proxy version 3.x
  (...)
  Oct 29 19:56:26 xenial-squid-reload-syntax squid[2684]: Squid Parent: (squid-1) process 2881 started
  Oct 29 19:56:26 xenial-squid-reload-syntax squid[2684]: Squid Parent: (squid-1) process 2881 exited with status 1
  Oct 29 19:56:26 xenial-squid-reload-syntax squid[2684]: Squid Parent: (squid-1) process 2881 will not be restarted due to repeated, frequent failures
  Oct 29 19:56:26 xenial-squid-reload-syntax squid[2684]: Exiting due to repeated, frequent failures

  With the fixed package, a reload action (for example) will flag the
  error, and keep the service running:

  ubuntu at xenial-squid-reload-syntax:~$ pidof squid
  3801

  ubuntu at xenial-squid-reload-syntax:~$ sudo service squid reload
  Job for squid.service failed because the control process exited with error code. See "systemctl status squid.service" and "journalctl -xe" for details.

  ubuntu at xenial-squid-reload-syntax:~$ echo $?
  1

  ubuntu at xenial-squid-reload-syntax:~$ pidof squid
  3801

  And the status message will be much clearer:
  ubuntu at xenial-squid-reload-syntax:~$ sudo service squid status
  ● squid.service - LSB: Squid HTTP Proxy version 3.x
  ...
  Oct 29 20:13:26 xenial-squid-reload-syntax systemd[1]: Reloading LSB: Squid HTTP Proxy version 3.x.
  Oct 29 20:13:26 xenial-squid-reload-syntax squid[3920]:  * FATAL: Invalid ACL type 'nonsense'
  Oct 29 20:13:26 xenial-squid-reload-syntax squid[3920]: FATAL: Bungled /etc/squid/squid.conf line 7897: acl nonsense nonsense nonsense
  Oct 29 20:13:26 xenial-squid-reload-syntax systemd[1]: squid.service: Control process exited, code=exited status=3
  Oct 29 20:13:26 xenial-squid-reload-syntax systemd[1]: Reload failed for LSB: Squid HTTP Proxy version 3.x.

  [Regression Potential]
+ This changes not only the reload action, but also start and consequently restart. The fix makes an existing safety net around those actions actually work, instead of being ignored.
+ Due to the lack of an explicit restart action in systemd, however, the restart guard in the SysV initscript doesn't take effect. If there is a bad config, and squid is restarted, the service will be in a stopped state at the end:
+ - stop will succeed
+ - start will fail: service remains stopped

-  * discussion of how regressions are most likely to manifest as a result
- of this change.
+ There is an upstream bug about it:
+ https://github.com/systemd/systemd/issues/2175

-  * It is assumed that any SRU candidate patch is well-tested before
-    upload and has a low overall risk of regression, but it's important
-    to make the effort to think about what ''could'' happen in the
-    event of a regression.
+ This is not a regression, however, as it's the same behavior as before.
+ We can't add the safety net around stop, and there is no way that I know
+ of to discover if the stop action being carried out is part of a restart
+ or not.

-  * This both shows the SRU team that the risks have been considered,
-    and provides guidance to testers in regression-testing the SRU.

  [Other Info]

   * Anything else you think is useful to include
   * Anticipate questions from users, SRU, +1 maintenance, security teams and the Technical Board
   * and address these questions in advance

  [Original Description]

  This is a very serious issue that got fixed upstream in:
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=800341

  It is also logged in the Ubuntu changelog as fixed in:

  squid3 (3.5.12-1) unstable; urgency=medium
    [ Mathieu Parent ]
    * Fix FATAL parsing before start/reload/restart (Closes: #800341)

  But is in fact not fixed.
  When I look in the source package I find two init scripts:
  squid3.rc and squid.rc. squid3.rc has the patch while squid.rc does not.

  The one being included in the package and deployed is the one that does
  not have the fix.

  I'm including a patch to fix this issue.
  Please push this out ASAP.

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Title:
  Init script fails test on reload/restart because of faulty regex

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