Provided by: libdancer2-perl_0.166001+dfsg-1_all 
NAME
Dancer2::Manual::Deployment - common ways to put your Dancer app into use
VERSION
version 0.166001
DESCRIPTION
Dancer has been designed to be flexible, and this flexibility extends to your choices when deploying your
Dancer app.
Running stand-alone
To start your application, just run plackup:
$ plackup bin/app.psgi
HTTP::Server::PSGI: Accepting connections at http://0:5000/
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.
Auto Reloading the Application
While developing your application, it is often handy to have the server automatically reload your
application when changes are made. There are two recommended ways of handling this with Dancer: using "
plackup -r " and Plack::Loader::Shotgun. Both have their advantages and disadvantages (which will be
explained below).
Regardless of the method you use, it is not recommended that you automatically reload your applications
in a production environment, for reasons of performance, deployment best practices, etc.
For Dancer 1 programmers that used the " auto_reload " option, please use one of these alternatives
instead:
Auto reloading with " plackup -r "
Plack's built-in reloader will reload your application anytime a file in your application's directory
(usually, /bin ) changes. You will likely want to monitor your lib/ directory too, using the " -R "
option:
$ plackup -r -R lib bin/app.psgi
There is a performance hit associated with this, as Plack will spin off a separate process that monitors
files in the application and other specified directories. If the timestamp of any files in a watched
directory changes, the application is recompiled and reloaded.
See the plackup docs for more information on the " -r " and " -R " options.
Auto reloading with plackup and Shotgun
There may be circumstances where Plack's built-in reloader won't work for you, be it for the way it looks
for changes, or because there are many directories you need to monitor, or you want to reload the
application any time one of the modules in Perl's lib/ path changes. Plack::Loader::Shotgun makes this
easy by recompiling the application on every request.
To use Shotgun, specify it using the loader argument to " plackup (-L) ":
$ plackup -L Shotgun bin/app.psgi
The Shotgun, while effective, can quickly cause you performance issues, even during the development phase
of your application. As the number of plugins you use in your application grows, as the number of static
resources (images, etc.) grows, the more requests your server process needs to handle. Since each request
recompiles the application, even simple page refreshes can get unbearably slow over time. Use with
caution.
You can bypass Shotgun's auto-reloading of specific modules with the " -M " switch:
$ plackup -L Shotgun -M<MyApp::Foo> -M<MyApp::Bar> bin/app.psgi
On Windows, Shotgun loader is known to cause huge memory leaks in a fork-emulation layer. If you are
aware of this and still want to run the loader, please use the following command:
> set PLACK_SHOTGUN_MEMORY_LEAK=1 && plackup -L Shotgun bin\app.psgi
HTTP::Server::PSGI: Accepting connections at http://0:5000/
Please note: if you are using Dancer 2's asynchronous capabilities, using Shotgun will kill Twiggy. If
you need async processing, consider an alternative to Shotgun.
Running as a cgi-script (or fast-cgi) under Apache
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
# /srv/www.example.com is the root of your
# dancer application
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.cgi$1 [QSA,L]
ErrorLog /var/log/apache2/www.example.com-error.log
CustomLog /var/log/apache2/www.example.com-access_log common
</VirtualHost>
Note that when using fast-cgi your rewrite rule should be:
RewriteRule ^(.*)$ /dispatch.fcgi$1 [QSA,L]
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"
on Debian or Ubuntu, 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 lines:
AddHandler cgi-script .cgi
To:
AddHandler fastcgi-script .fcgi
Running on PSGI-based Perl webservers
A number of Perl web servers supporting PSGI are available on cpan:
Starman <http://search.cpan.org/dist/Starman/>
"Starman" is a high performance web server, with support for preforking, signals, multiple
interfaces, graceful restarts and dynamic worker pool configuration.
Twiggy <http://search.cpan.org/dist/Twiggy/>
"Twiggy" is an "AnyEvent" web server, it's light and fast.
Corona <http://search.cpan.org/dist/Corona/>
"Corona" is a "Coro" based web server.
Similar to running standalone, use plackup to start your application (see Plack and specific servers
above for all available options):
$ plackup bin/app.psgi
$ plackup -E deployment -s Starman --workers=10 -p 5001 -a bin/app.psgi
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::Middleware"
in Plack): Plack::Middleware::Deflater. It's a middleware to encode the response body in gzip or
deflate, based on the "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 handler (usually app.psgi) edit it to use Plack::Builder, as
described above:
use Dancer2;
use MyWebApp;
use Plack::Builder;
builder {
enable 'Deflater';
dance;
};
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".
Creating a service
You can turn your app into proper service running in background using one of the following examples:
Using Ubic
Ubic is an extensible perlish service manager. You can use it to start and stop any services,
automatically start them on reboots or daemon failures, and implement custom status checks.
A basic PSGI service description (usually in "/etc/ubic/service/application"):
use parent qw(Ubic::Service::Plack);
# if your application is not installed in @INC path:
sub start {
my $self = shift;
$ENV{PERL5LIB} = '/path/to/your/application/lib';
$self->SUPER::start(@_);
}
__PACKAGE__->new(
server => 'Starman',
app => '/path/to/your/application/app.psgi',
port => 5000,
user => 'www-data',
);
Run "ubic start application" to start the service.
Using daemontools
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.psgi -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 my_webapp
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.
Using HAProxy
"HAProxy" is a reliable high-performance TCP/HTTP load balancer written in C available from
<http://haproxy.1wt.eu/>.
Suppose we want to run an application at "app.example.com:80" and would to use two backends listen on
hosts "app-be1.example.com:3000" and "app-be2.example.com:3000".
Here is HAProxy configuration file (haproxy.conf):
global
nbproc 1
maxconn 4096
user nobody
group nobody
# haproxy logs will be collected by syslog
# syslog: unix socket path or tcp pair (ipaddress:port)
log /var/run/log local0
daemon
# enable compression (haproxy v1.5-dev13 and above required)
tune.comp.maxlevel 5
defaults
log global
option httpclose
option httplog
option dontlognull
option forwardfor
option abortonclose
mode http
balance roundrobin
retries 3
timeout connect 5s
timeout server 30s
timeout client 30s
timeout http-keep-alive 200m
# enable compression (haproxy v1.5-dev13 and above required)
compression algo gzip
compression type text/html application/javascript text/css application/x-javascript text/javascript
# application frontend (available at http://app.example.com)
frontend app.example.com
bind :80
# modify request headers
reqadd X-Forwarded-Proto:\ http
reqadd X-Forwarded-Port:\ 80
# modify response headers
rspdel ^Server:.*
rspdel ^X-Powered-By:.*
rspadd Server:\ Dethklok\ (Unix/0.2.3)
rate-limit sessions 1024
acl is-haproxy-stats path_beg /stats
# uncomment if you'd like to get haproxy usage statistics
# use_backend haproxy if is-haproxy-stats
default_backend dynamic
# haproxy statistics (available at http://app.example.com/stats)
backend haproxy
stats uri /stats
stats refresh 180s
stats realm app.example.com\ haproxy\ statistics
# change credentials
stats auth admin1:password1
stats auth admin2:password2
stats hide-version
stats show-legends
# application backends
backend dynamic
# change path_info to check and value of the Host header sent to application server
option httpchk HEAD / HTTP/1.1\r\nHost:\ app.example.com
server app1 app-be1.example.com:3000 check inter 30s
server app2 app-be2.example.com:3000 check inter 30s
We will need to start the workers on each backend of our application. This can be done by starman
utility:
# on app-be1.example.com
$ starman --workers=2 --listen :3000 /path/to/app.pl
# on app-be2.example.com
$ starman --workers=2 --listen :3000 /path/to/app.pl
Then start the haproxy itself:
# check the configuration..
$ sudo haproxy -c -f haproxy.conf
# now really start it..
$ sudo haproxy -f haproxy.conf
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
PerlResponseHandler Plack::Handler::Apache2
PerlSetVar psgi_app /websites/myapp.example.com/app.psgi
</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 use the following example Apache configuration.
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 5000 bin/app.psgi
This example configuration uses a socket:
$HTTP["url"] =~ "^/app" {
fastcgi.server += (
"/app" => (
"" => (
"socket" => "/tmp/fcgi.sock",
"check-local" => "disable",
)
)
)
}
Launch your application:
plackup -s FCGI --listen /tmp/fcgi.sock bin/app.psgi
AUTHOR
Dancer Core Developers
COPYRIGHT AND LICENSE
This software is copyright (c) 2010 by Alexis Sukrieh.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.
AUTHOR
Dancer Core Developers
COPYRIGHT AND LICENSE
This software is copyright (c) 2015 by Alexis Sukrieh.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5
programming language system itself.
perl v5.22.1 2016-02-13 Dancer2::Manual::Deployment(3pm)