Sinatra Extension: StaticAssets
Gem sinatra-static-assets implements the following helpers methods:
image_tag
stylesheet_link_tag
javascript_script_tag
link_to
link_favicon_tag
To install it, run:
sudo gem install sinatra-static-assets -s http://gemcutter.org
All these methods are simple wrappers around the uri
method
from the sinatra gem.
When will you need it?
Whenever you use the
Passenger module for Apache2
or use Rack::URLMap
to dispatch an application to
sub URI.
Example: Suppose that we already have a virtual host hitch.local
and two Sinatra applications that live in
/home/me/www/summer
and /home/me/www/winter
directories, respectively.
We want our Sinatra applications to be accessible from
the following sub URI:
http://hitch.local/summer
and
http://hitch.local/winter
To configure Apache2 and Passenger to serve our applications we need to create a new configuration file with the following content:
<VirtualHost *:80>
ServerName hitch.local
DocumentRoot /srv/www/hitch.local
RackBaseURI /summer
RackBaseURI /winter
</VirtualHost>
and a link to the applications directories in /srv/www/hitch.local
:
ln -s /home/me/www/summer/public /srv/www/hitch.local/summer
ln -s /home/me/www/winter/public /srv/www/hitch.local/winter
After restarting an Apache2 server and visiting, for example, the first
application at http://hitch.local/summer
we see that links to
images, stylesheets and javascripts are broken.
The hitch here is that in Sinatra applications we usually refer to images/stylesheets/javascripts with absolute URI:
/images/tatry1.jpg /stylesheets/app.css /javascripts/app.js
That setup works whenever we are running applications locally. The absolute URI above tells a browser to request images (stylesheets and javascripts) from:
http://localhost:4567/images/tatry1.jpg
which in turn, tells a server to send a file:
/home/me/www/summer/public/images/tatry1.jpg
The public
directory is the default directory where static files
should be served from.
So, the /images/tatry1.jpg
picture will be there and will be served
unless we had changed that default directory.
But these absolute URIs do not work when, for example,
the summer application is dispatched to /summer
sub URI.
As a result the images are at:
http://hitch.local/summer/images/tatry1.jpg
but we request them from:
http://hitch.local/images/tatry1.jpg
And this does not work because there is no application dispatched to images sub URI.
The recommended way to deal with an absolute URI
is to use a helper method that automatically converts
/images/tatry1.jpg
to /summer/images/tatry1.jpg
for application dispatched to /summer
sub URI.
In the above example you can simply remove the <img>
HTML tag and replace it with a Ruby inline code like this:
<%= image_tag("/images/tatry1.jpg", :alt => "Błyszcz, 2159 m") %>
See also, How to fix broken images/CSS/JavaScript URIs in sub-URI deployments
Usage examples
In HTML (and HTML5) <link>
and <img>
tags have no end tag.
In XHTML, on the contrary, these tags must be properly closed.
We can choose the appropriate behaviour with closed option:
image_tag "/images/tatry1.jpg", :alt => "Błyszcz, 2159 m", :closed => true
The default value of closed option is false
. We can change the default value with:
enable :xhtml
We can pass mutliple stylesheets or scripts:
stylesheet_link_tag "/stylesheets/screen.css", "/stylesheets/summer.css", :media => "projection"
javascript_script_tag "/javascripts/jquery.js", "/javascripts/summer.js", :charset => "iso-8859-2"
link_to "Tatry Mountains Rescue Team", "/topr"
In order to use include the following in a Sinatra application:
require 'sinatra/static_assets'
Or, if subclassing Sinatra::Base
, include helpers manually:
require 'sinatra/static_assets'
class Summer < Sinatra::Base
register Sinatra::StaticAssets
# ...
end
Dispatching reusable Sinatra applications
With the latest version of Sinatra it is possible to build
reusable Sinatra applications. This means that multiple Sinatra applications
can be run in isolation and co-exist peacefully with other Rack
based applications. Subclassing Sinatra::Base
creates such a
reusable application.
The example
directory contains two reusable Sinatra applications:
rsummer, rwinter and a rackup file rconfig.ru
which
dispatches these applications to /summer
and /winter
sub URI:
$LOAD_PATH.unshift('rsummer')
require 'summer'
$LOAD_PATH.unshift('rwinter')
require 'winter'
map '/summer' do
run Sinatra::Summer.new
end
map '/winter' do
run Sinatra::Winter.new
end
Run rconfig.ru
file with:
rackup -p 3000 rconfig.ru
This file could also be used to deploy to virtual host's root with Passenger.
To this end, create an Apache2 configuration file with the following content:
<VirtualHost *:80>
ServerName hitch.local
DocumentRoot /srv/www/hitch.local
</VirtualHost>
Next, create directories required by Passenger:
mkdir /srv/www/hitch.local/{public,tmp}
and, finally, copy config.ru
into /srv/www/hitch.local
and
update LOAD_PATH
in the copied file.
With everything in place, after restarting Apache2, the applications are accessible from the
http://hitch.local/summer
and
http://hitch.local/winter
respectively.
Miscellaneous stuff
1. The examples
directory contains summer and winter applications.
2. In order to create a virual host add the following to /etc/hosts/:
127.0.0.1 localhost.localdomain localhost hitch.local
or, read editing /etc/hosts is waste of my time.