NAME

Dancer::Deployment - common ways to put your Dancer app into use

DESCRIPTION

Dancer has been designed to be flexible, and this flexibility extends to your choices when deploying your Dancer app.

Running as a cgi-script (or fast-cgi)

In providing ultimate flexibility in terms of deployment, your Dancer app can be run as a simple cgi-script out-of-the-box. No additional web-server configuration needed. Your web server should recognize .cgi files and be able to serve Perl scripts. The Perl module Plack::Runner is required.

Start by adding the following to your apache configuration (httpd.conf or sites-available/*site*):

    <VirtualHost *:80>
        ServerName www.example.com
        DocumentRoot /srv/www.example.com/public
    	ServerAdmin you@example.com

   		<Directory "/srv/www.example.com/public">
           AllowOverride None
           Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
           Order allow,deny
           Allow from all
           AddHandler cgi-script .cgi
   		</Directory>

   		RewriteEngine On
   		RewriteCond %{REQUEST_FILENAME} !-f
   		RewriteRule ^(.*)$ /dispatch.fcgi$1 [QSA,L]

        ErrorLog  /var/log/apache2/www.example.com-error.log
        CustomLog /var/log/apache2/www.example.com-access_log common
	</VirtualHost>

Here, the mod_rewrite magic for Pretty-URLs is directly put in Apache's configuration. But if your web server supports .htaccess files, you can drop those lines in a .htaccess file.

To check if your server supports mod_rewrite type apache2 -l to list modules. To enable mod_rewrite (Debian), run a2enmod rewrite. Place following code in a file called .htaccess in your application's root folder:

# BEGIN dancer application htaccess
RewriteEngine On
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f
RewriteRule (.*) /dispatch.cgi$1 [L]
# END dancer application htaccess

Now you can access your dancer application URLs as if you were using the embedded web server.

http://localhost/

This option is a no-brainer, easy to setup, low maintenance but serves requests slower than all other options.

You can use the same technique to deploy with FastCGI, by just changing the line:

AddHandler cgi-script .cgi

By:

AddHandler fastcgi-script .fcgi

Of course remember to update your rewrite rules, if you have set any:

RewriteRule (.*) /dispatch.fcgi$1 [L]

Running stand-alone

At the simplest, your Dancer app can run standalone, operating as its own webserver using HTTP::Simple::PSGI.

Simply fire up your app:

$ perl bin/app.pl
>> Listening on 0.0.0.0:3000
== Entering the dance floor ...

Point your browser at it, and away you go!

This option can be useful for small personal web apps or internal apps, but if you want to make your app available to the world, it probably won't suit you.

Running on Perl webservers with plackup

A number of Perl web servers supporting PSGI are available on cpan:

Starman: Starman is a high performance web server, with support for preforking, signals, ...
Twiggy: Twiggy is an AnyEvent web server, it's light and fast.
Corona: Corona is a Coro based web server.

To start your application, just run plackup (see Plack and specific servers above for all available options):

$ plackup bin/app.pl
$ plackup -E deployment -s Starman --workers=10 -p 5001 -a bin/app.pl

As you can see, the scaffolded Perl script for your app can be used as a PSGI startup file.

Enabling content compression

Content compression (gzip, deflate) can be easily enabled via a Plack middleware (see Plack#Plack::Middleware): Plack::Middleware::Deflater. It's a middleware to encode the response body in gzip or deflate, based on Accept-Encoding HTTP request header.

Enable it as you would enable any Plack middleware. First you need to install Plack::Middleware::Deflater, then in the configuration file (usually environments/development.yml), add these lines:

plack_middlewares:
  -
    - Plack::Middleware::Deflater
    - ...

These lines tell Dancer to add Plack::Middleware::Deflater to the list of middlewares to pass to Plack::Builder, when wrapping the Dancer app. The syntax is :

as key: the name of the Plack middleware to use
as value: the options to pass it as a list. In our case, there is no option to specify to Plack::Middleware::Deflater, so we use an empty YAML list.

To test if content compression works, trace the HTTP request and response before and after enabling this middleware. Among other things, you should notice that the response is gzip or deflate encoded, and contains a header Content-Encoding set to gzip or deflate

Running multiple apps with Plack::Builder

You can use Plack::Builder to mount multiple Dancer applications on a PSGI webserver like Starman.

Start by creating a simple app.psgi file:

use Dancer ':syntax';
use Plack::Builder;

setting apphandler => 'PSGI';

my $app1 = sub {
    my $env = shift;
    setting appdir => '/path/to/app1',
    setting appname => 'app1';
    load_app "app1";
    Dancer::Config->load;
    my $request = Dancer::Request->new( env => $env );
    Dancer->dance( $request );
};
my $app2 = sub {
    my $env = shift;
    setting appdir => '/path/to/app2',
    setting appname => 'app2';
    load_app "app2";
    Dancer::Config->load;
    my $request = Dancer::Request->new( env => $env );
    Dancer->dance( $request );
};

builder {
    mount "/app1" => builder {$app1};
    mount "/app2" => builder {$app2};
};

and now use Starman

plackup -a app.psgi -s Starman

Using daemontools to create a service

daemontools is a collection of tools for managing UNIX services. You can use it to easily start/restart/stop services.

A basic script to start an application: (in /service/application/run)

#!/bin/sh

# if your application is not installed in @INC path:
export PERL5LIB='/path/to/your/application/lib'

exec 2>&1 \
/usr/local/bin/plackup -s Starman -a /path/to/your/application/app.pl -p 5000

Running stand-alone behind a proxy / load balancer

Another option would be to run your app stand-alone as described above, but then use a proxy or load balancer to accept incoming requests (on the standard port 80, say) and feed them to your Dancer app.

This could be achieved using various software; examples would include:

Using Apache's mod_proxy

You could set up a VirtualHost for your web app, and proxy all requests through to it:

<VirtualHost mywebapp.example.com:80>
ProxyPass / http://localhost:3000/
ProxyPassReverse / http://localhost:3000/
</VirtualHost>

Or, if you want your webapp to share an existing VirtualHost, you could have it under a specified dir:

ProxyPass /mywebapp/ http://localhost:3000/
ProxyPassReverse /mywebapp/ http://localhost:3000/

It is important for you to note that the Apache2 modules mod_proxy and mod_proxy_http must be enabled.

a2enmod proxy
a2enmod proxy_http

It is also important to set permissions for proxying for security purposes, below is an example.

<Proxy *>
  Order allow,deny
  Allow from all
</Proxy>

Using perlbal

perlbal is a single-threaded event-based server written in Perl supporting HTTP load balancing, web serving, and a mix of the two, available from http://www.danga.com/perlbal/

It processes hundreds of millions of requests a day just for LiveJournal, Vox and TypePad and dozens of other "Web 2.0" applications.

It can also provide a management interface to let you see various information on requests handled etc.

It could easily be used to handle requests for your Dancer apps, too.

It can be easily installed from CPAN:

perl -MCPAN -e 'install Perlbal'

Once installed, you'll need to write a configuration file. See the examples provided with perlbal, but you'll probably want something like:

CREATE POOL my_dancers
POOL my_dancers ADD 10.0.0.10:3030
POOL my_dancers ADD 10.0.0.11:3030
POOL my_dancers ADD 10.0.0.12:3030
POOL my_dancers ADD 10.0.0.13:3030

CREATE SERVICE my_webapp
SET listen          = 0.0.0.0:80
SET role            = reverse_proxy
SET pool            = my_dancers
SET persist_client  = on
SET persist_backend = on
SET verify_backend  = on
ENABLE balancer

Using balance

balance is a simple load-balancer from Inlab Software, available from http://www.inlab.de/balance.html.

It could be used simply to hand requests to a standalone Dancer app. You could even run several instances of your Dancer app, on the same machine or on several machines, and use a machine running balance to distribute the requests between them, for some serious heavy traffic handling!

To listen on port 80, and send requests to a Dancer app on port 3000:

balance http localhost:3000

To listen on a specified IP only on port 80, and distribute requests between multiple Dancer apps on multiple other machines:

balance -b 10.0.0.1 80 10.0.0.2:3000 10.0.0.3:3000 10.0.0.4:3000

Using Lighttpd

You can use Lighttp's mod_proxy:

$HTTP["url"] =~ "/application" {
    proxy.server = (
        "/" => (
            "application" => ( "host" => "127.0.0.1", "port" => 3000 )
        )
    )
}

This configuration will proxy all request to the /application path to the path / on localhost:3000.

Using Nginx

with Nginx:

upstream backendurl {
    server unix:THE_PATH_OF_YOUR_PLACKUP_SOCKET_HERE.sock;
}

server {
  listen       80;
  server_name YOUR_HOST_HERE;

  access_log /var/log/YOUR_ACCESS_LOG_HERE.log;
  error_log  /var/log/YOUR_ERROR_LOG_HERE.log info;

  root YOUR_ROOT_PROJECT/public;
  location / {
    try_files $uri @proxy;
    access_log off;
    expires max;
  }

  location @proxy {
        proxy_set_header Host $http_host;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass       http://backendurl;
  }

}

You will need plackup to start a worker listening on a socket :

cd YOUR_PROJECT_PATH
sudo -u www plackup -E production -s Starman --workers=2 -l THE_PATH_OF_YOUR_PLACKUP_SOCKET_HERE.sock -a bin/app.pl

A good way to start this is to use daemontools and place this line with all environments variables in the "run" file.

Running from Apache

You can run your Dancer app from Apache using the following examples:

Running from Apache with Plack

You can run your app from Apache using PSGI (Plack), with a config like the following:

<VirtualHost myapp.example.com>
    ServerName www.myapp.example.com
    ServerAlias myapp.example.com
    DocumentRoot /websites/myapp.example.com

    <Directory /home/myapp/myapp>
        AllowOverride None
        Order allow,deny
        Allow from all
    </Directory>

    <Location />
        SetHandler perl-script
        PerlHandler Plack::Handler::Apache2
        PerlSetVar psgi_app /websites/myapp.example.com/app.pl
    </Location>

    ErrorLog  /websites/myapp.example.com/logs/error_log
    CustomLog /websites/myapp.example.com/logs/access_log common
</VirtualHost>

To set the environment you want to use for your application (production or development), you can set it this way:

<VirtualHost>
    ...
    SetEnv DANCER_ENVIRONMENT "production"
    ...
</VirtualHost>

Running from Apache under appdir

If you want to deploy multiple applications under the same VirtualHost, using one application per directory for example, you can do the following.

This example uses the FastCGI dispatcher that comes with Dancer, but you should be able to adapt this to use any other way of deployment described in this guide. The only purpose of this example is to show how to deploy multiple applications under the same base directory/virtualhost.

<VirtualHost *:80>
    ServerName localhost
    DocumentRoot "/path/to/rootdir"
    RewriteEngine On
    RewriteCond %{REQUEST_FILENAME} !-f

    <Directory "/path/to/rootdir">
        AllowOverride None
        Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch
        Order allow,deny
        Allow from all
        AddHandler fastcgi-script .fcgi
    </Directory>

    RewriteRule /App1(.*)$ /App1/public/dispatch.fcgi$1 [QSA,L]
    RewriteRule /App2(.*)$ /App2/public/dispatch.fcgi$1 [QSA,L]
    ...
    RewriteRule /AppN(.*)$ /AppN/public/dispatch.fcgi$1 [QSA,L]
</VirtualHost>

Of course, if your Apache configuration allows that, you can put the RewriteRules in a .htaccess file directly within the application's directory, which lets you add a new application without changing the Apache configuration.

Running on lighttpd (CGI)

To run as a CGI app on lighttpd, just create a soft link to the dispatch.cgi script (created when you run dancer -a MyApp) inside your system's cgi-bin folder. Make sure mod_cgi is enabled.

ln -s /path/to/MyApp/public/dispatch.cgi /usr/lib/cgi-bin/mycoolapp.cgi

Running on lighttpd (FastCGI)

Make sure mod_fcgi is enabled. You also must have FCGI installed.

This example configuration uses TCP/IP:

$HTTP["url"] == "^/app" {
    fastcgi.server += (
        "/app" => (
            "" => (
                "host" => "127.0.0.1",
                "port" => "5000",
                "check-local" => "disable",
            )
        )
    )
}

Launch your application:

plackup -s FCGI --port 8080 bin/app.pl

This example configuration uses a socket:

$HTTP["url"] =~ "^/app" {
    fastcgi.server += (
        "/app" => (
            "" => (
                "socket" => "/tmp/fcgi.sock",
                "check-local" => "disable",
            )
        )
    )
}