Search Results: "Daniel Lange"

21 June 2020

Daniel Lange: Upgrading Limesurvey with (near) zero downtime

Limesurvey is an online survey tool. It is very powerful and commonly used in academic environments because it is Free Software (GPLv2+), allows for local installations protecting the data of participants and allowing to comply with data protection regulations. This also means there are typically no load-balanced multi-server szenarios with HA databases. But simple VMs where Limesurvey runs and needs upgrading in place. There's an LTS branch (currently 3.x) and a stable branch (currently 4.x). There's also a 2.06 LTS branch that is restricted to paying customers. The main developers behind Limesurvey offer many services from template design to custom development to support to hosting ("Cloud", "Limesurvey Pro"). Unfortunately they also charge for easy updates called "ComfortUpdate" (currently 39 for three months) and the manual process is made a bit cumbersome to make the "ComfortUpdate" offer more attractive. Due to Limesurvey being an old code base and UI elements not being clearly separated, most serious use cases will end up patching files and symlinking logos around template directories. That conflicts a bit with the opaque "ComfortUpdate" process where you push a button and then magic happens. Or you have downtime and a recovery case while surveys are running. If you do not intend to use the "ComfortUpdate" offering, you can prevent Limesurvey from connecting to http://comfortupdate.limesurvey.org daily by adding the updatable stanza as in line 14 to limesurvey/application/config/config.php:
  1. return array(
  2. [...]
  3. // Use the following config variable to set modified optional settings copied from config-defaults.php
  4. 'config'=>array(
  5. // debug: Set this to 1 if you are looking for errors. If you still get no errors after enabling this
  6. // then please check your error-logs - either in your hosting provider admin panel or in some /logs directory
  7. // on your webspace.
  8. // LimeSurvey developers: Set this to 2 to additionally display STRICT PHP error messages and get full access to standard templates
  9. 'debug'=>0,
  10. 'debugsql'=>0, // Set this to 1 to enanble sql logging, only active when debug = 2
  11. // Mysql database engine (INNODB MYISAM):
  12. 'mysqlEngine' => 'MYISAM'
  13. , // Update default LimeSurvey config here
  14. 'updatable' => false,
  15. )
  16. );
The comma on line 13 is placed like that in the current default limesurvey config.php, don't let yourself get confused. Every item in a php array must end with a comma. It can be on the next line. The basic principle of low risk, near-zero downtime, in-place upgrades is:
  1. Create a diff between the current release and the target release
  2. Inspect the diff
  3. Make backups of the application webroot
  4. Patch a copy of the application in-place
  5. (optional) stop the web server
  6. Make a backup of the production database
  7. Move the patched application to the production webroot
  8. (if 5) Start the webserver
  9. Upgrade the database (if needed)
  10. Check the application
So, in detail: Continue reading "Upgrading Limesurvey with (near) zero downtime"

14 April 2020

Daniel Lange: I think we need more creativity in statistics

" 'Boa constrictors swallow their prey whole, without chewing it. After that they are not able to move, and they sleep through the six months that they need for digestion.' I pondered deeply, then, over the adventures of the jungle. And after some work with a colored pencil I succeeded in making my first drawing. My Drawing Number One. It looked something like this: Boa Constrictor by Antoine de Saint Exup ry I showed my masterpiece to the grown-ups, and asked them whether the drawing frightened them. But they answered: 'Frighten? Why should any one be frightened by a hat?' My drawing was not a picture of a hat. It was a picture of a boa constrictor digesting an elephant. But since the grown-ups were not able to understand it, I made another drawing: I drew the inside of a boa constrictor, so that the grown-ups could see it clearly. They always need to have things explained. My Drawing Number Two looked like this: Boa Constrictor in sectional drawing by Antoine de Saint Exup ry The grown-ups' response, this time, was to advise me to lay aside my drawings of boa constrictors, whether from the inside or the outside, and devote myself instead to geography, history, arithmetic, and grammar. That is why, at the age of six, I gave up what might have been a magnificent career as a painter. I had been disheartened by the failure of my Drawing Number One and my Drawing Number Two. Grown-ups never understand anything by themselves, and it is tiresome for children to be always and forever explaining things to them." from The Little Prince by Antoine de Saint Exup ry Outcome of Cases (Recovery or Death) in Germany by Worldometers from the Corona Fun with Statistics department at Worldometers (source, archive.org link)

11 May 2017

Daniel Lange: Thunderbird startup hang (hint: Add-Ons)

If you see Thunderbird hanging during startup for a minute and then continuing to load fine, you are probably running into an issue similar to what I saw when Debian migrated Icedove back to the "official" Mozilla Thunderbird branding and changed ~/.icedove to ~/.thunderbird in the process (one symlinked to the other). Looking at the console log (=start Thunderbird from a terminal so you see its messages), I got: 
console.log: foxclocks.bootstrap._loadIntoWindow(): got xul-overlay-merged - waiting for overlay-loaded
[.. one minute delay ..]
console.log: foxclocks.bootstrap._windowListener(): got window load chrome://global/content/commonDialog.xul
Stracing confirms it hangs because Thunderbird loops waiting for a FUTEX until that apparently gets kicked by a XUL core timeout.
(Thanks for defensive programming folks!) So in my case uninstalling the Add-On Foxclocks easily solved the problem. I assume other Thunderbird Add-Ons may cause the same issue, hence the more generic description above.

8 January 2017

Bits from Debian: New Debian Developers and Maintainers (November and December 2016)

The following contributors got their Debian Developer accounts in the last two months: The following contributors were added as Debian Maintainers in the last two months: Congratulations!

26 June 2016

Clint Adams: A local script for local people

This isn't actually answering the question, but it's close. It's also horrible, so whoever adopts Enrico's script should also completely rewrite this or burn it along with the stack of pizza boxes and the grand piano. Input: 
#!/bin/zsh
set -e
PATHS=$(tempfile)
NEWKEYS=$(tempfile)
NEWKEYRING=$(tempfile)
FARTHEST_TEN=$(tempfile)
trap "rm -f $ PATHS  $ NEWKEYS  $ NEWKEYRING  $ FARTHEST_TEN " EXIT
keyring=$ 1:-ksp-dc16.gpg 
myfpr=$ 2:-2100A32C46F895AF3A08783AF6D3495BB0AE9A02 
#keyserver=$ 3:-http://pool.sks-keyservers.net:11371/ 
# this doesn't handle hokey fetch failures
#(for fpr in $(hkt list --keyring $ keyring  --output-format JSON   jq '.[].publickey.fpr')
#do
#  hokey fetch --keyserver "$ keyserver " --validation-method MatchPrimaryKeyFingerprint "$ (Q)fpr "
#done) >$ NEWKEYS 
#
#gpg2 --no-default-keyring --keyring $ NEWKEYRING  --import $ NEWKEYS 
cp "$ keyring " "$ NEWKEYRING "
gpg2 --no-default-keyring --keyring $ NEWKEYRING  --refresh
hkt findpaths --keyring $ NEWKEYRING  '' '' '' > $ PATHS 
id=$(awk -F, "/$ myfpr )\$/  sub(/\(/,BLANKY,\$1);print \$1; " $ PATHS )
grep -e ",\[$ id ," -e ",$ id \]" $ PATHS    sort -n   tail -n 10 > $ FARTHEST_TEN 
targetids=($ (f)"$ $((sed 's/^.*\[//;s/,.*$//;' $ FARTHEST_TEN ; sed 's/\])$//;s/.*,//;' $ FARTHEST_TEN )   sort -n -u   grep -v "^$ id $") " )
targetfprs=($(for i in $ targetids ; do awk -F, "/\($ i ,[^[]/  sub(/\)/,BLANKY,\$2); print \$2 " $ PATHS ; done))
gpg2 --no-default-keyring --keyring $ NEWKEYRING  --list-keys $ targetfprs
Output: 
pub   rsa4096/0x664F1238AA8F138A 2015-07-14 [SC]
      Key fingerprint = 3575 0B8F B6EF 95FF 16B8  EBC0 664F 1238 AA8F 138A
uid                   [ unknown] Daniel Lange <dl.ml1@usrlocal.de>
sub   rsa4096/0x03BEE1C11DB1954B 2015-07-14 [E]
pub   rsa4096/0xDF23DA3396978EB3 2014-09-05 [SC]
      Key fingerprint = BBBC 58B4 5994 CF9C CC56  BCDA DF23 DA33 9697 8EB3
uid                   [  undef ] Michael Meskes <michael@fam-meskes.de>
uid                   [  undef ] Michael Meskes <meskes@postgresql.org>
uid                   [  undef ] Michael Meskes <michael.meskes@credativ.com>
uid                   [  undef ] Michael Meskes <meskes@debian.org>
sub   rsa4096/0x85C3AFFECF0BF9B5 2014-09-05 [E]
sub   rsa4096/0x35D857C0BBCB3B25 2014-11-04 [S]
pub   rsa4096/0x1E953E27D4311E58 2009-07-12 [SC]
      Key fingerprint = C2FE 4BD2 71C1 39B8 6C53  3E46 1E95 3E27 D431 1E58
uid                   [  undef ] Chris Lamb <chris@chris-lamb.co.uk>
uid                   [  undef ] Chris Lamb <lamby@gnu.org>
uid                   [  undef ] Chris Lamb <lamby@debian.org>
sub   rsa4096/0x72B3DBA98575B3F2 2009-07-12 [E]
pub   rsa4096/0xDF6D76C44D696F6B 2014-08-15 [SC] [expires: 2017-06-03]
      Key fingerprint = 1A6F 3E63 9A44 67E8 C347  6525 DF6D 76C4 4D69 6F6B
uid                   [ unknown] Sven Bartscher <sven.bartscher@weltraumschlangen.de>
uid                   [ unknown] Sven Bartscher <svenbartscher@yahoo.de>
uid                   [ unknown] Sven Bartscher <kritzefitz@debian.org>
sub   rsa4096/0x9E83B071ED764C3A 2014-08-15 [E]
sub   rsa4096/0xAEB25323217028C2 2016-06-14 [S]
pub   rsa4096/0x83E33BD7D4DD4CA1 2015-11-12 [SC] [expires: 2017-11-11]
      Key fingerprint = 0B5A 33B8 A26D 6010 9C50  9C6C 83E3 3BD7 D4DD 4CA1
uid                   [ unknown] Jerome Charaoui <jerome@riseup.net>
sub   rsa4096/0x6614611FBD6366E7 2015-11-12 [E]
sub   rsa4096/0xDB17405204ECB364 2015-11-12 [A] [expires: 2017-11-11]
pub   rsa4096/0xF823A2729883C97C 2014-08-26 [SC]
      Key fingerprint = 8ED6 C3F8 BAC9 DB7F C130  A870 F823 A272 9883 C97C
uid                   [ unknown] Lucas Kanashiro <kanashiro@debian.org>
uid                   [ unknown] Lucas Kanashiro <kanashiro.duarte@gmail.com>
sub   rsa4096/0xEE6E5D1A9C2F5EA6 2014-08-26 [E]
pub   rsa4096/0x2EC0FFB3B7301B1F 2014-08-29 [SC] [expires: 2017-04-06]
      Key fingerprint = 76A2 8E42 C981 1D91 E88F  BA5E 2EC0 FFB3 B730 1B1F
uid                   [ unknown] Niko Tyni <ntyni@debian.org>
uid                   [ unknown] Niko Tyni <ntyni@cc.helsinki.fi>
uid                   [ unknown] Niko Tyni <ntyni@iki.fi>
sub   rsa4096/0x129086C411868FD0 2014-08-29 [E] [expires: 2017-04-06]
pub   rsa4096/0xAA761F51CC10C92A 2016-06-20 [SC] [expires: 2018-06-20]
      Key fingerprint = C9DE 2EA8 93EE 4C86 BE73  973A AA76 1F51 CC10 C92A
uid                   [ unknown] Roger Shimizu <rogershimizu@gmail.com>
sub   rsa4096/0x2C2EE1D5DBE7B292 2016-06-20 [E] [expires: 2018-06-20]
sub   rsa4096/0x05C7FD79DD03C4BB 2016-06-20 [S] [expires: 2016-09-18]
Note that this completely neglects potential victims who are unconnected within the KSP set.

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