Interacting with Docker containers

• Running an interactive shell on the container:
  

  
  # Your container may have /bin/sh instead
  docker exec -t -i [container] /bin/bash
  

  
  
• Running a command on an image instead (i.e not a running instance):
  

  
  docker run -t -i [image] /bin/bash
  

  
  
• Get the output of a running container (for logs etc):
  

  
  docker attach --no-stdin [container]

Cleaning docker

You can use the following bash script to clean out your docker instance:

#!/bin/bash
echo "docker-clean.sh [container|image|volume|cache|data|debugbar]"
if [ "$1" == "container" ]; then
    #Cleaning containers
    docker ps --no-trunc -aqf "status=exited" | xargs docker rm
elif [ "$1" == "image" ]; then
    #Cleaning images
    docker images --no-trunc -aqf "dangling=true" | xargs docker rmi
elif [ "$1" == "volume" ]; then
    #Cleaning volumes
    docker volume ls -qf "dangling=true" | xargs docker volume rm
fi

Using HSQLDB

These notes are for dealing with the HSQL database used in a legacy web application.

HSQL database commands

Note: These commands are required to by run where the hsqldb jar file is stored

• Starting the server:

  
  java -cp /var/lib/hsqldb/lib/hsqldb.jar org.hsqldb.Server -database.0 file:mydb -dbname.0 phonebook

  
  
• Start the GUI application for the HSQL database:
  
  

  java -cp /var/lib/hsqldb/lib/hsqldb.jar org.hsqldb.util.DatabaseManagerSwing

SQLTOOL

An Example ~/sqltool.rc file:

urlid localhost-sa
url jdbc:hsqldb:hsql://localhost/
username SA
password

To use SQL Tool:

1. Setup a ~/sqltool.rc to store the connection settings for the database (and run the server).
2. Once you have started the database (using the commands in the previous section), run the SQLTool command line utility:
   
   

   java -cp /var/lib/hsqldb/lib/hsqldb.jar:sqltool.jar org.hsqldb.cmdline.SqlTool

   
   
3. Connect to the database as indication by the urlid in your sqltool.rc file:
   
   

   \j localhost-sa

   
   
4. You can stop sqltool at any using
   
   

   \xq (table OR SELECT QUERY)

DATABASE INFO

• Grab list of all tables in the database:
  
  

  SELECT TABLE_SCHEM,TABLE_NAME FROM INFORMATION_SCHEMA.SYSTEM_TABLES WHERE TABLE_TYPE = 'TABLE';

  
  
• Grabbing a single employee record:
  
  

  SELECT LIMIT 0 1 - FROM EMPLOYEES;

  
  
• Outputting user info as a CSV file:
  
  

  SELECT A.USERNAME, A.PASSWORD, A.FIRSTNAME, A.LASTNAME, A.MIDDLENAME as OTHERNAME, B.EMAIL INTO TEXT "users_file" FROM USERS AS A INNER JOIN USER_DETAILS AS B ON A.USERNAME = B.USERNAME;

  
  
• Removing the temporary users table used to create the CSV file:
  
  

  DROP TABLE "users";

  
  
• Date based search query where date is a string (DD-MM-YYYY):
  
  

  SELECT A.USERNAME, B.FIRSTNAME FROM USERS AS A INNER JOIN EMPLOYEES AS B ON A.USERNAME = B.USERNAME WHERE SUBSTRING(A.EXPIRY,7,4) > 2016;

  
  
• Searching for string partials:
  
  

  SELECT TIMES, DATES, USERS FROM LOGS WHERE USERS LIKE 'admin%' AND DATES LIKE '%/03/2015';

  
  
• Grabbing the exact number of matches that match parameters:
  
  

  code>SELECT BUILDING, INCTYPE, COUNT(*) AS NUM FROM REPORTS WHERE BUILDING LIKE 'PLACE %' AND DATE LIKE '%/2015' GROUP BY BUILDING, INCTYPE;

Useful projects to check out (2017 collection)

I have been building a list of projects and packages to check out throughout last year and I decided to consolidate them as a post.

Laravel

• Laravel Auditing will track changes to Eloquent models
• Ziggy is a laravel package that outputs router information in JSON form
• Ardent, a Laravel Model extension

PHP

• churn-php analyses your codebase for potential refactoring candidates
• Behat, for testing code - https://github.com/Behat/Behat

Vue.js

• vue-good-wizard is a simple step-by-step wizard plugin
• vue-directive-tooltip is a simple tooltip plugin

SSL

• SSL security suite check

Postgresql

• pgBackRest - Back-up
• Plogical - replication 

Removing hyphenated text and word-wrapping via CSS

A simple bit of code to use if you do not like the way your browser hyphenates or word wraps your text. (Note the * selector will apply this CSS to ALL elements on the page, and the !important flag will overwrite any later changes.)

* {
 -webkit-hyphens: none !important;
 -ms-hyphens: none !important;
 -o-hyphens: none !important;
 hyphens: none !important;
}

Using SVG color filters

This is a follow on from my previous post about showing a sprite image using the SVG.js library. We will now add a colour filter to the image using the svg.filter.js plugin.

The color matrix is a 5 column, 4 row matrix. Each row represents an RGBA value, and each column is a multiplier for that particular colour value. Every column represents an RGBA multiplier, which intensifies (or reduces) the resulting colour value based on the original input value. The last column is just a straight value that just gets added on.

So for the following matrix:

1 0 0 0 0
0 1 0 0 0
0 0 1 0 0
0 0 0 1 0

The output image will have the exact same colour value as the input image. This is because the the RGBA multipliers simple times the input RGBA value by 1.

Here are some resources:

• Finessing 'feColorMatrix'
• Color Filters can turn your gray skies blue
• A handy tool to play around with SVG color matrices

The following code shows off the concept.

var col = {
    x: 2,
    y: 0,
}
var draw = SVG('drawing2').size(300, 300)
var clip = draw.clip()
var rect = draw.rect(32, 32)
var image = draw.image('http://icons.iconarchive.com/icons/iconfactory/star-trek-ships/icons-390.jpg')

image.move(-1*(32+5)*col.x-5,-1*(32+5)*col.y-5);

image.filter(function(add) {
  add.colorMatrix('matrix', [ 1.0, 0,   0,   0,   0
                            , 0,   0.2, 0,   0,   0
                            , 0,   0,   0.2, 0,   0
                            , 0,   0,   0,   1.0, 0 ])
})
clip.add(rect)

image.clipWith(clip)