| title | layout | id |
|---|---|---|
Sinatra: Configuring Settings |
default |
configuration |
Sinatra includes a number of built-in settings that control whether certain
features are enabled. Settings are application-level variables that are
modified using one of the set, enable, or disable methods and are
available within the request context via the settings object. Applications
are free to set custom settings as well as the default, built-in settings
provided by the framework.
In its simplest form, the set method takes an setting name and value and
creates an attribute on the application. Settings can be accessed within
requests via the settings object:
{% highlight ruby %} set :foo, 'bar'
get '/foo' do "foo is set to " + settings.foo end {% endhighlight %}
When the setting value is a Proc, evaluation is performed when the setting
is read so that other settings may be used to calculate the value:
{% highlight ruby %} set :foo, 'bar' set :baz, Proc.new { "Hello " + foo }
get '/baz' do "baz is set to " + settings.baz end {% endhighlight %}
The /baz response should come as "baz is set to Hello bar" unless the
foo setting is modified.
Multiple settings can be set by passing a Hash to set. The previous example
could be rewritten with:
{% highlight ruby %} set :foo => 'bar', :baz => Proc.new { "Hello " + foo } {% endhighlight %}
The enable and disable methods are sugar for setting a list of settings
to true or false, respectively. The following two code examples are
equivalent:
{% highlight ruby %} enable :sessions, :logging disable :dump_errors, :some_custom_option {% endhighlight %}
Using set:
{% highlight ruby %} set :sessions, true set :logging, true set :dump_errors, false set :some_custom_option, false {% endhighlight %}
A symbol specifying the deployment environment; typically set to one of
:development, :test, or :production. The :environment defaults to
the value of the RACK_ENV environment variable (ENV['RACK_ENV']), or
:development when no RACK_ENV environment variable is set.
The environment can be set explicitly:
set :environment, :production
Support for encrypted, cookie-based sessions are included with Sinatra but are disabled by default. Enable them with:
set :sessions, true
Sessions are implemented by inserting the Rack::Session::Cookie
component into the application's middleware pipeline.
Writes a single line to STDERR in Apache common log format when enabled.
This setting is enabled by default in classic style apps and disabled by
default in Sinatra::Base subclasses.
Internally, the Rack::CommonLogger component is used to generate
log messages.
Boolean specifying whether the HTTP POST _method parameter hack should be
enabled. When true, the actual HTTP request method is overridden by the
value of the _method parameter included in the POST body. The _method
hack is used to make POST requests look like other request methods (e.g.,
PUT, DELETE) and is typically only needed in shitty environments -- like
HTML form submission -- that do not support the full range of HTTP methods.
The POST _method hack is implemented by inserting the
Rack::MethodOverride component into the middleware pipeline.
The directory used as a base for the application. By default, this is
assumed to be the directory containing the main application file
(:app_file setting). The root directory is used to construct the default
:public and :views settings. A common idiom is to set the :root setting
explicitly in the main application file as follows:
set :root, File.dirname(__FILE__)
Boolean that determines whether static files should be served from the
application's public directory (see the :public setting). When :static is
truthy, Sinatra will check if a static file exists and serve it before
checking for a matching route.
The :static setting is enabled by default when the public directory
exists.
A string specifying the directory where static files should be served from.
By default, this is assumed to be a directory named "public" within the root
directory (see the :root setting). You can set the public directory
explicitly with:
set :public, '/var/www'
The best way to specify an alternative directory name within the root of the
application is to use a deferred value that references the :root setting:
set :public, Proc.new { File.join(root, "static") }
A string specifying the directory where view templates are located. By
default, this is assumed to be a directory named "views" within the
application's root directory (see the :root setting). The best way to
specify an alternative directory name within the root of the application is
to use a deferred value that references the :root setting:
set :views, Proc.new { File.join(root, "templates") }
Boolean specifying whether the built-in web server is started after the app
is fully loaded. By default, this setting is enabled only when the
:app_file matches $0. i.e., when running a Sinatra app file directly
with ruby myapp.rb. To disable the built-in web server:
set :run, false
String or Array of Rack server handler names. When the :run setting is
enabled, Sinatra will run through the list and start a server with the
first available handler. The :server setting is set as follows by default:
set :server, %w[thin mongrel webrick]
String specifying the hostname or IP address of the interface to listen on
when the :run setting is enabled. The default value -- '0.0.0.0' -- causes
the server to listen on all available interfaces. To listen on the
loopback interface only, use:
set :bind, 'localhost'
The port that should be used when starting the built-in web server when the
:run setting is enabled. The default port is 4567. To set the port
explicitly:
set :port, 9494
The :app_file setting is used to calculate the default :root,
:public, and :views setting values. A common idiom is to override the
default detection heuristic by setting the :app_file explicitly from
within the main application file:
set :app_file, __FILE__
It's also used to detect whether Sinatra should boot a web server when using classic-style applications.
Boolean specifying whether backtraces are written to STDERR when an
exception is raised from a route or filter. This setting is enabled by
default in classic style apps. Disable with:
set :dump_errors, false
Boolean specifying whether exceptions raised from routes and filters should
escape the application. When disabled, exceptions are rescued and mapped to
error handlers which typically set a 5xx status code and render a custom
error page. Enabling the :raise_errors setting causes exceptions to be
raised outside of the application where it may be handled by the server
handler or Rack middleware, such as Rack::ShowExceptions or
Rack::MailExceptions.
Sinatra can be used in threaded environments where more than a single
request is processed at a time. However, not all applications and libraries
are thread-safe and may cause intermittent errors or general weirdness.
Enabling the :lock setting causes all requests to synchronize on a mutex
lock, ensuring that only a single request is processed at a time.
The :lock setting is disabled by default.
Enable error pages that show backtrace and environment information when an unhandled exception occurs. Enabled in development environments by default.