When you have a multi-server setup, you'll be adding a new server from time to time. Before doing a full deploy, you might want to test that server in an isolated deploy. There is a single way to do this: the HOSTFILTER env variable.

Commenting out "server" lines in the Capistrano deploy config will raise a Capistrano::NoMatchingServersError with <task> is only run for servers matching {:roles=> <role>}, but no servers matched. Instead, specify the server-under-test like this:

HOSTFILTER=separate-sidekiq.makandra.de cap productio...

Ubuntu might create several keyrings for you. Note that keyring passwords are initially set to the user password but do not change with it. If you can't seem to find the correct password for a keyring, try entering the inital password.

If you still can't find it, you might have to delete that keyring:

• open "Passwords and Keys" (seahorse application)
• right-click on the keyring you want to change
• press Delete

These tools help you in checking websites globally:

DNS Checker

This tool allows for global DNS propagation checking.

GeoScreenshot

This tool takes screenshots of a given URL from various locations across the world.

This is useful if, for example, you want to use a background-image that has to scale with the width and the div should only have the height of the picture.

html:

<div class="outer">
  <div class="inner">
  </div>
</div>

css:

.outer {
  width: 100%;
  background-image: image-url('background.png');
  background-size: cover;
}
  
.inner {
  padding-top: 60%;
}

How does it work?

There are several CSS attributes that can handle values as percentage. But they use different other attributes as "reference value...

Webmocks hash_including is similar to RSpec::Mocks::ArgumentMatchers#hash_including. Be aware that hash_including (webmock v3.0.1) doesn't parse integer values to String.

Without hash including you would say:

uri = URI('http://example.com/?foo=1&bar=2')
stub_request(:get, 'example.com').with(query: {foo: 1, bar: 2})
Net::HTTP.get(uri) # ===> Success

If you only want to check if foo is present you can use hash_including:

uri = URI('http://example.com/?foo=1&bar=2')
stub_request(:get, 'example.com').with(query: hash_i...

You can use gem list to list all gems available from a remote gem server:

gem list -r --clear-sources -s 'https://user:password@gemserver.tld/'

This is useful to debug cases where Bundler complains of a gem existing in more than one gem source.

Ruby's standard library is in the process of being gemified. It will soon - Ruby 2.5 - consist of RubyGems, which can be updated independently from Ruby.

This might mean smoother Ruby upgrades in the future. If breaking API changes happen in standard gems, we can update these before upgrading Ruby.

TLDR: Browser implementations of HTTP/2 push are horrible. You might end up with worse performance than without pushing. However, the article includes a great explanation of how HTTP/2 push are supposed to integrate with browser APIs.

If you stub a method or set expectations with should_receive these stubbed methods may also yield blocks. This is handy if the returning object is receiving a block call.

Consider this, where you cannot say and_return [] because of the block:

def crawl_messages
  Message.find_in_batches do |messages|
    messages.each(&:crawl)
  end
end

It works similar to and_return -- just use and_yield:

describe '#crawl_messages' do
  it 'should proc...

By default Middleman generates files with a .html extension. Because of this all your URLs end in /foo.html instead of /foo, which looks a bit old school.

To get prettier URLs, Middleman lets you activate :directory_indexes in config.rb. This makes a directory for each of your pages and puts a single file index.html into it, e.g. /foo/index.html. This lets you access pages with http://domain/foo.

Don't double your requests!

Unfortunately you are now forcing every br...

Middleman is a static page generator that brings many of the goodies that Rails developers are used to.

Out of the box, Middleman brings Haml, Sass, helpers etc. However, it can be configured to do even better. This card is a list of improvement hints for a Rails developer.

Gemfile

Remove tzinfo-data and wdm unless you're on Windows. Add these gems:

gem 'middleman-livereload'
gem 'middleman-sprockets' # Asset pipeline!

gem 'bootstrap-sass' # If you want to use Bootstrap

gem 'byebug'

gem 'capistrano'
gem 'capistrano-mid...

Sometimes, through some firewall or proxy misconfiguration, you might have to deploy to a server that cannot access the git repository.

Solution 1: HTTP Proxy (this is the preferred fix)

SSH can be tunneled over an HTTP Proxy. For example, when the repo is on github, use this:

1. Install socat

2. Add a ~/.ssh/config on the target server(s) with permission 0600 and this content:

   Host github.com ssh.github.com
     User git
     Hostname ssh.github.com
     Port 443
     ProxyCommand socat - PROXY:<your proxyhost>:%h:%p,...
   

Dump this method into your Ruby console to quickly print data in columns. This is helpful for e.g. comparing attributes of a set of Rails records.

def tp(objects, *method_names)
  terminal_width = `tput cols`.to_i
  cols = objects.count + 1 # Label column
  col_width = (terminal_width / cols) - 1 # Column spacing

  Array(method_names).map do |method_name|
    cells = objects.map{ |o| o.send(method_name).inspect }
    cells.unshift(method_name)

    puts cells.map{ |cell| cell.to_s.ljust(col_width) }.join ' '
  end

  nil
end

Usag...

Assuming you're wanting to undo the effects of git rm or rm followed by git add -A or something similar:

This restores the file status in the index:

git reset -- <file>

then check out a copy from the index

git checkout -- <file>

To undo git add , the first line above suffices, assuming you haven't committed yet.

Note:

Make sure to use double dashes -- to tell git to checkout a file instead of a branch. This only is relevant for [files having the same name as a branch](https://git-scm.com/docs/git-ch...

In case you want to require a gem, that is not in the Gemfile of you bundle and therefore not in your loadpath, you need to add the path manually and require the gem afterwards.

Expected error

Requiring a gem, that is not in the Gemfile or .gemspec, will cause an LoadError exception:

require 'example_gem' => LoadError: cannot load such file -- example_gem

Adding a gem to the loadpath temporary

1. You need to install the gem

gem install 'example_gem'

2. Then you need to require the path where the gem was install...

Solved with flexbox is a collection of css problems which were hard or impossible to solve without flexbox:

• Better, Simpler Grid Systems
• Holy Grail Layout
• Input Add-ons
• Media Object
• Sticky Footer
• Vertical Centering

RubyMine provides a visual tool for resolving merge conflicts locally.

Follow

Git > Resolve Conflicts

in the context menu to open RubyMine's merge conflict tool.

• Left pane: local copy (read-only)
• Right pane: checked in version from repository (read-only)
• Central pane: base revision from which both conflicting versions are derived

You can also use a similar pane view to compare to files.
Mark two files and press Ctrl + D to compare.

Luckily, this is simple. Just install three packages:

sudo apt install ipheth-utils libimobiledevice-dev libimobiledevice-utils

Then turn on the "Personal Hotspot" in iPhone settings, connect it to your Ubuntu machine via USB and you should be up and running.

Imagine the following HTML structure, where the scrolling container has overflow-y: scroll:

+--scrolling container+-+
|                       |
| +-child element+----+ |
| | ++iframe++        | |
| | |        |        | |
| | |        |        | |
+-----------------------+
  | |        |        |   <-- actually cut off by
  | +--------+        |   <-- scrolling container
  +-------------------+

The issue: On iOS, the child element cannot be scrolled when grabbing the iframe (i.e. putting your finger somewhere on the iframe).
...

When you load a dump for development, records may reference images that are not available on your machine.

Requests to those images may end up on your application, e.g. if a catch-all route is defined that leads to a controller doing some heavy lifting. On pages with lots of missing images, this slows down development response times.

You can fix that by defining a Rails route like this:

if Rails.env.development?
  scope format: true, constraints: { format: /jpg|png|gif/ } do
    get '/*anything', to: proc { [404, {}, ['']] }

...

Small web application where you can upload an image (PNG, JPEG, GIF) and generate a base64-encoded version of it.

You can copy the result as

• HTML <img> tag with data URI,
• CSS rule with background-image and data URI,
• plain Base64-encoded data URI string.

Sometimes you want/have to send specific http(s) requests. You can do that easy with curl or just write the request yourself.

make a http request with nc

nc example.com 80
GET / HTTP/1.1
Host: example.com
# press enter

make a http request with telnet

telnet example.com 80
GET / HTTP/1.1
Host: example.com
# press enter

make https request with openssl

openssl s_client -connect example.com:443
GET / HTTP/1.1
Host: example.com
# press enter

You can specify more headers if you want:

nc example.c...

For the initial setup or changes in the sentry reporting it might be useful to enabled reporting of sentry in development. Don't commit these changes and prefer to report to the staging environment. As other developers might be confused of these errors try to given them a proper message and delete them afterwards.

1. Add config.raven_dsn = 'your-dns' in config/environments/development.rb.
2. Add development to existing environments in the Raven.configure block: config.environments = ['development', 'staging', 'production'].
3. ...