Note

The maintenance mode is enabled on all application server as soon as the file /public/system/maintenance.html is present.

Installation

Add this line to your application's Gemfile:

 gem 'capistrano', '~> 3.0'
 gem 'capistrano-maintenance', '~> 1.0'

Add this line to you application's Capfile:

require 'capistrano/maintenance'

Enable task

Present a maintenance page to visitors. Disables your application's web interface by writing a #{maintenance_basename}.html file to each web server. The servers m...

To delete a certificate request run sudo puppet ca destroy $your.full.hostname on your puppetmaster.

Until recently, you could open a new tab via window.open when using execute_script in Selenium tests. It no longer works in Chrome (will show a "popup blocked" notification).

This is because browsers usually block window.open unless the user interacted with an element for security reasons. I am not sure why it did work via Selenium before.

Here is an approach that will insert a link into the page, and have Selenium click it:

path = "/your/path/here"
id = "helper_#{SecureRandom.hex(8)}"
execute_script <<-JAVASCRIPT
  ...

E-mails are usually encoded using Quoted Printable. Here is how to decode or encode such strings.

You probably know Quoted Printable from e-mail bodies appearing in Rails logs, where =s become =3Ds in URLs, or where long lines are split up and trailed by = after each split.

Decode Quoted Printable

Decoding such strings is actually quite simple using plain Ruby:

"foo=3Dbar".unpack('M')[0]
# => "foo=bar"

Note that unpack will return an array. Our result is the 1st item.
...

A collection of 700+ svg vector logos. The logos are optimized (removed duplicated paths / excessive groups / empty defs, linting, etc).
Almost 100 logos were recreated from rastered images #vectorized.

All logos appearing on the site are the property of their respective owners.

http://svgporn.com/

You know that Devise offers RSpec test helpers for controller specs. However, in request specs, they will not work.

Here is a solution for request specs, adapted from the Devise wiki. We will simply use Warden's test helpers -- you probably already load them for your Cucumber tests.

First, we define sign_in and sign_out methods. These will behave just like ...

As we get an exception notification, when a cron job fails, we wish to have the full backtrace in this mail. A rake task doesn't output the full backtrace by default, so you need the --backtrace option.

Trigger

You will find fail mails with a shortened backtrace

#[...]
Tasks: TOP => some_namespace:some_task
(See full trace by running task with --trace)

What rake wants from you
Running the rake task like rake some_namespace:some_task --backtrace

How this works with whenever
Define a own job_type and use it for r...

I had a very frequent cronjob that in rare cases could be relatively slow. To avoid multiple instances of this cronjob running in parallel, I decided to use flock to ensure that only one instance could run at a time.

flock works by acquiring a lock to a file, and if it can do so running a command. In order not to wait but simply give up when the file is locked, you can add -n:

flock /tmp/my.task.lock -n -c "bin/my-long-running-job"

Using whenever, and since this was a rake task, the follo...

Table of contents of the linked article:

What are Web Fonts?

• Advantages of Web Fonts
• Disadvantages of Web Fonts
  • Fallback Fonts
  • CSS3 @font Declaration Example
  • Fallback Font Example
  • Render Blocking and Critical Rendering Path
  • FOIT

Optimizing Web Font Delivery Further

• Prioritize Based On Browser Support
• Choose Only Styles You Need
• Character Sets
• Host Fonts Locally or Prefetch
• Store in LocalStorage with Base64 Encoding
• Another Method

Web Font Pe...

While you can use Apache as a reverse proxy, it tries to be too smart. Try nginx instead, it's much simpler to set up.

After struggling with Apache for quite a while, since I simply could not make it pass through the Digest Authentication of my target host (that I proxied to), I switched to nginx. Here is what I did.

1. Have nginx

   sudo apt-get install nginx
   

2. Define your nginx config, e.g. at /etc/nginx/conf.d/reverse-proxy.conf:

   server {
     listen 127.0.0.1;
     
     location /...
   

While you usually do not need a Content-Type on GET request (which have a blank body), an external API may still force you to send one.
Angular's $http service will strip that header when the request data (body) is blank. [1] This is possibly a misconception of RFC2616.

Here is how to send GET requests with a Content-Type header in Angular.

Example

Consider this request:

$http({ me...

Web fonts are great. They are also be really bad for front-end performance because they block rendering. You may have experienced this on a slow cellular network. Staring at a blank page is no fun, especially when the content has already loaded.

This talk explores why browser have placed fonts on the critical path, and how we can work around this while still delivering a good user experience. It also takes a look at what the future will bring to web font performance: preloading hints, the font-display property, and HTTP/2.

Our applications not only need to be functional, they need to be fast.

But, to quote Donald Knuth,

premature optimization is the root of all evil (or at least most of it) in programming

The reasoning is that you should not waste your time optimizing code where it does not even matter. However, I believe there are some kinds of optimizations you should do right away, because

• they are either obvious and easy
• or they are very hard to do optimize later

This is an attempt to list some of those things:

On the server

...

Starting with Ruby 1.9, most #each methods can be called without a block, and will return an enumerator. This is what allows you to do things like

['foo', 'bar', 'baz'].each.with_index.collect { |name, index| name * index }
# -> ["", "bar", "bazbaz"]

If you write your own each method, it is useful to follow the same practice, i.e. write a method that

• calls a given block for all entries
• returns an enumerator, if no block is given

How to write a canonical each method

To write a m...

A fantastic guide for a dilemma facing any web-based product.

Here’s a simple set of Yes/No questions that you can quickly answer before you add another item to your product roadmap.

Saying yes to a feature request – whether it’s a to an existing customer, a product enquiry, a teammate, or a manager – is immediately rewarding. It’s an unspoken transaction where you barter long term product focus in exchange for short term satisfaction. Buying short term joy for the cost of long term pain is the human condition.

1. Does it fit your ...

To safely transport an arbitrary string within a URL, you need to percent-encode characters that have a particular meaning in URLs, like & or =.

If you are using Rails URL helpers like movies_path(:query => ARBITRARY_STRING_HERE), Rails will take care of the encoding for you. If you are building URLs manually, you need to follow this guide.

Ruby

In Ruby, use CGI.escape:

# ✅ good
CGI.escape('foo=foo&bar=bar')
=> "foo%3Dfoo%26bar%3Dbar"

Do not ever use `URI.en...

As the web is being used for more and more tasks, expectations rise. Not only should web pages offer rich interaction, they must be responsive in both size and interaction.

This imposes a paradoxon that needs to be solved by building performing applications. It's not enough any more to have your web site do crazy stuff, it is also required to do it crazy fast. This card is intended to give you an introduction to this emerging aspect of web development.

Read this introductory [performance study on Pinterest](http://www.smashingmagazine.com/...

While debugging an intricate issue with failed HTTP requests I have come to appreciate the more advanced features of the httpclient Rubygem.

The gem is much more than a lightweight wrapper around Ruby's net/http. In particular:

• A single HTTPClient instance can re-use persistent connections across threads in a thread-safe way.
• Has a custom and configurable SSL certificate store (which you probably want to disable by default...

I recommend install Node.js using nvm. This way you can have multiple Node versions in your ~/.nvm. You also won't need to install global packages with sudo anymore.

Node via nvm will automatically bring npm. yarn will automatically be available if corepack is enabled for node.

Installing nvm

DigitalOcean has a HOWTO for installing nvm on Ubuntu (16.04, [18.04](https://www.digitalocean.com/community/tutorials/how-to-...

Ruby has Enumerable.find(&block), which returns the first item in the collection for which the block evaluates to true.

first_post_with_image = posts.find do |post|
  post.image
end

However, sometimes it's not the item you're interested in, but some value depening on it – e.g. the value the block evaluated to. You could first map the collection and then take the first truthy value, but this way you need to process the whole collection twice:

first_image_url = posts.map(&:image).find(&:present?).url

If the mapping ...

You can include files from app/assets or from the public folder with javascript_include_tag. The subtle difference that tells rails how to build the path correctly is a single slash at the beginning of the path:

<%= javascript_include_tag('ckeditor/config') %> # for assets/ckeditor/config.js
<%= javascript_include_tag('/ckeditor/ckeditor') %> # for public/ckeditor/ckeditor.js

This also applies to stylesheet_link_tag.

Note that when you refer to a Javascript or stylesheet in /assets you need to add it to [the list of asse...

A word of caution

There should rarely be a reason for you to split up config/routes.rb. If you need to, probably your whole application should be split up.

Split it anyway

Rails::Engine looks at config.paths['config/routes.rb'] and registers its value with app.routes_reloader. This means you could put routing files anywhere and then require them. However, I recommend to put any routing files into config/routes/:

# config/routes/example.rb

Rails.application.routes.draw do
 resources :example
end

After creating y...

tig is a command line explorer for Git that is just awesome. Install via apt-get or brew.

Handy commands

• t ("tree"): Directory-structure based access. You'll see the current directory annotated with the latest change date and its author. Navigate with arrow keys or vim.
• b ("blame"): Opens the file under the cursor and annotates each line with change date and author.
• d ("diff"): Like ENTER on a commit, but arrow keys will scroll the diff!
• /: Search current view (e.g. commit list, diff). Jump to next hit with n....