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Upgrading Limesurvey with (near) zero downtime

Open Source

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 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"

Fixing the Nextcloud menu to show more than eight application icons


I have been late to adopt an on-premise cloud solution as the security of Owncloud a few years ago wasn't so stellar (cf. my comment from 2013 in Encryption files ... for synchronization across the Internet). But the follow-up product Nextcloud has matured quite nicely and we use it for collaboration both in the company and in FLOSS related work at multiple nonprofit organizations.

There is a very annoying "feature" in Nextcloud though that the designers think menu items for apps at the top need to be limited to eight or less to prevent information overload in the header. The whole item discussion is worth reading as it it an archetypical example of design prevalence vs. user choice.

And of course designers think they are right. That's a feature of the trade.
And because they know better there is no user configurable option to extend that 8 items to may be 12 or so which would prevent the annoying overflow menu we are seeing with 10 applications in use:

Screenshot of stock Nextcloud menu

Luckily code can be changed and there are many comments floating around the Internet to change const minAppsDesktop = 8. In this case it is slightly complicated by the fact that the javascript code is distributed in compressed form (aka "minified") as core/js/dist/main.js and you probably don't want to build the whole beast locally to change one constant.


const breakpoint_mobile_width = 1024;

const resizeMenu = () => {
    const appList = $('#appmenu li')
    const rightHeaderWidth = $('.header-right').outerWidth()
    const headerWidth = $('header').outerWidth()
    const usePercentualAppMenuLimit = 0.33
    const minAppsDesktop = 8
    let availableWidth = headerWidth - $('#nextcloud').outerWidth() - (rightHeaderWidth > 210 ? rightHeaderWidth : 210)
    const isMobile = $(window).width() < breakpoint_mobile_width
    if (!isMobile) {
        availableWidth = availableWidth * usePercentualAppMenuLimit
    let appCount = Math.floor((availableWidth / $(appList).width()))
    if (isMobile && appCount > minAppsDesktop) {
        appCount = minAppsDesktop
    if (!isMobile && appCount < minAppsDesktop) {
        appCount = minAppsDesktop

    // show at least 2 apps in the popover
    if (appList.length - 1 - appCount >= 1) {

    $('#more-apps a').removeClass('active')
    let lastShownApp
    for (let k = 0; k < appList.length - 1; k++) {
        const name = $(appList[k]).data('id')
        if (k < appCount) {
            $('#apps li[data-id=' + name + ']').addClass('in-header')
            lastShownApp = appList[k]
        } else {
            $('#apps li[data-id=' + name + ']').removeClass('in-header')
            // move active app to last position if it is active
            if (appCount > 0 && $(appList[k]).children('a').hasClass('active')) {
                $('#apps li[data-id=' + $(lastShownApp).data('id') + ']').removeClass('in-header')
                $('#apps li[data-id=' + name + ']').addClass('in-header')

    // show/hide more apps icon
    if ($('#apps li:not(.in-header)').length === 0) {
    } else {

gets compressed during build time to become part of one 15,000+ character line. The relevant portion reads:

var f=function(){var e=s()("#appmenu li"),t=s()(".header-right").outerWidth(),n=s()("header").outerWidth()-s()("#nextcloud").outerWidth()-(t>210?t:210),i=s()(window).width()<1024;i||(n*=.33);var r,o=Math.floor(n/s()(e).width());i&&o>8&&(o=8),!i&&o<8&&(o=8),e.length-1-o>=1&&o--,s()("#more-apps a").removeClass("active");for(var a=0;a<e.length-1;a++){var l=s()(e[a]).data("id");a<o?(s()(e[a]).removeClass("hidden"),s()("#apps li[data-id="+l+"]").addClass("in-header"),r=e[a]):(s()(e[a]).addClass("hidden"),s()("#apps li[data-id="+l+"]").removeClass("in-header"),o>0&&s()(e[a]).children("a").hasClass("active")&&(s()(r).addClass("hidden"),s()("#apps li[data-id="+s()(r).data("id")+"]").removeClass("in-header"),s()(e[a]).removeClass("hidden"),s()("#apps li[data-id="+l+"]").addClass("in-header")))}0===s()("#apps li:not(.in-header)").length?(s()("#more-apps").hide(),s()("#navigation").hide()):s()("#more-apps").show()}

Well, we can still patch that, can we?

Continue reading "Fixing the Nextcloud menu to show more than eight application icons"