Added a text stroke via CSS

You can add a text stroke (or outline) to your HTML documents by using the following piece of CSS code:

text-shadow: -1px -1px 0 black,
              1px -1px 0 black,
             -1px 1px 0 black,
              1px 1px 0 black;

SCSS/SASS Relative Luminence

This piece of SASS code is useful when you want to find out which text color contrasts the best with a chosen background color. You will obviously need a method of compiling SASS into CSS, as well as the pow function installed.

The technique was borrowed from the W3 recommendation.

@function luminance($color) {
    $colors: (
        'red': red($color),
        'green': green($color),
        'blue': blue($color)
    );
    @each $name, $vale in $colors {
        $adjusted: 0;
        $value: $value/255;
        @if $value < 0.03928 {
            $value: $value/12.92;
        } else {
            $value: ($value + 0.55)/1.055;
            $value: pow($value,2.4);
        }
        $colors: map-merge($colors, ($name: $value));
    }
    @return (map-get($colors, 'red')*0.2126)
        + (map-get($colors, 'green')*0.7152)
        + (map-get($colors, 'blue')*0.0722);
}

Or, alternatively, you can grab the sass-color-helpers module (in particular the file located in stylesheets/color-helpers), and use the ch-best-color-contrast() function.

Chrome Headless mode

Chrome has a headless mode which is generally for testing (and scripting). You can invoke it as follows:

/usr/bin/google-chrome --headless --disable-gpu --print-to-pdf http://localhost:8080/

Webpack, code-splitting, require & require.ensure()

Webpack allows for global definitions to be defined and set, allowing for compile time switches. This is especially useful when compiling a single source for multiple targets.

require() will include the target as a whole, while require.ensure() will create a code split point. Paired with the above concept of Webpack compile time switches, this allows us to define a code-splitted and and non-split version of our code.

An example:

In webpack.config.js:

plugins: [
    new webpack.DefinePlugin({
        BUILD_PDF: JSON.stringify(true),
    }),
]

In the target .js source:

if (BUILD_PDF) {
    require(....),
} else {
    require.ensure([], () =>{
        require(....);
    }, err => {
        // error code
    }, "split-name");
}

PHP XDebug tips and tricks

A quick step-by-step walkthrough on how to get XDebug working properly and interfacing with your IDE of choice.

1. Install XDebug on the PHP server (or docker instance). This will enable XDebug on your PHP code.
   

   apt-get install --no-install=recommends php5-xdebug

   
   
2. Configure /etc/php5/mods-available/xdebug.ini on the server to enable XDebug (check the documentation for more details about the settings).
   

   
   zend_extension=xdebug.so
   xdebug.remote_enable=1
   xdebug.remote_autostart=1
   xdebug.remote_connect_back=1
   xdebug.remote_host=10.0.0.1
   xdebug.max_nesting_level=500
   

   
   
3. Ensure that the port 9000 (you can change this in the above config file) is open on the server (configure your firewall). If PHP is running as a docker service, you may need to expose/map the port and then configure your firewall to allow connections.
   
4. Download or install a client program to pass the XDebug IDEKEY to the server while browsing
   
5. Configure your IDE to listen on port 9000 of the server for XDebug messages

Note: You should use the browser on the same machine you have your IDE set-up, as PHP XDebug will send messages to that and only that client (depending on the configuration options).

Recover LVM Boot partition within a live CD (installing GRUB)

This allows you to recover the Master Boot record when a RAID 5 array fails.

1. Activate LVM partitions

   sudo mdadm --assemble --scan
   sudo vgchange -a y [name of volume group]

2. Mount all volumes to a single mount-point

   sudo mount /dev/mapper/[volume group]/[root volume] /mnt/
   sudo mount /dev/mapper/[volume group]/[usr volume] /mnt/usr/
   sudo mount /dev/mapper/[volume group]/[home volume] /mnt/home/
   ... etc

3. Mount and bind directories for grub to detect the underlying hardware

   sudo mount --bind /dev /mnt/dev
   sudo mount --bind /dev/pts /mnt/dev/pts
   sudo mount --bind /proc /mnt/proc
   sudo mount --bind /sys /mnt/sys

4. Jump into the new mounted system

   sudo chroot /mnt

5. Install GRUB

   grub-install /dev/sda
   grub-install --recheck /dev/sda
   update-grub

6. Exit the environment and restart

   exit
   sudo umount /mnt/dev/pts
   sudo umount /mnt/*
   sudo shutdown -r now

Recovering a RAID 5 array

Recently had a RAID 5 array fail on me. These are the steps I took to recover the data.

NOTE! The order of the disks in /dev/sdX follows the numbering of the ports on the motherboard. So if a disk is plugged into port 0, it will show up as /dev/sda. Keep this in mind as if you remove a failed disk, it might mess up the references in the array!.

1. Boot up from a Live CD
2. Install the software RAID management software

   sudo apt-get install mdadm

3. Make sure RAID and LVM are unmounted

   sudo vgchange -a n [name of your volume group]  sudo mdadm -S /dev/md0

4. Copy the failed disk to the new disk (in case the disk was the boot disk, you need to copy that flag across so that your system boots)

   sudo sfdisk -d /dev/sdx | sudo sfdisk /dev/sdy

5. Check that the disks are the same

   sudo fdisk -l

6. Mount the RAID array, and remove the failed disk

   sudo mdadm --assemble --scan  sudo mdadm --manage --remove /dev/sdx

7. Add the new disk

   sudo mdadm --manage --add /dev/sdy

8. Watch the progress as mdadm rebuilds your RAID array

   sudo cat /proc/mdstat