Provided by: libdancer-perl_1.3120+dfsg-1_all 
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) 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>
ScriptAlias / /srv/www.example.com/public/dispatch.cgi/
ErrorLog /var/log/apache2/www.example.com-error.log
CustomLog /var/log/apache2/www.example.com-access_log common
</VirtualHost>
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
...
ScriptAlias / /srv/www.example.com/public/dispatch.cgi
To:
AddHandler fastcgi-script .fcgi
...
ScriptAlias / /srv/www.example.com/public/dispatch.fcgi
Running stand-alone
At the simplest, your Dancer app can run standalone, operating as its own webserver using
HTTP::Server::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 and
more.
Twiggy
"Twiggy" is an "AnyEvent" web server, it's light and fast.
Corona
"Corona" is a "Coro" based web server.
WARNING: "Dancer"'s use of global variables and "Coro"'s threaded behaviors can cause
some unexpected behaviors. See this GitHub issue
<https://github.com/PerlDancer/Dancer/issues/929> for more details. Unless you have
really, really strongly compelling reasons to use Corona, consider using "Twiggy" or
"Starman" instead.
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"
Hosting on DotCloud
The simplest way to achieve this is to push your main application directory to dotcloud
with your "bin/app.pl" file copied to (or symlinked from) "app.psgi".
Beware that the dotcloud service enforces one environment only, named "deployment". So
instead of having "environments/development.yml" or "environments/production.yml" you must
have a file named "environments/deployment.yml".
Also make sure that your "Makefile.PL" (or other dependency mechanism) includes both
Dancer and Plack::Request.
The default in-memory session handler won't work, and instead you should switch to
something persistent. Edit "config.yml" to change "session: 'Simple'" to (for example)
"session: 'YAML'".
In case you have issues with Template::Toolkit on Dotcloud
If you use the Template::Toolkit and its "INCLUDE" or "PROCESS" directives, you might need
to add the search path of your view files to the config. This is probably going to be
something like "INCLUDE_PATH: '/home/dotcloud/current/views'" in "config.yml".
An alternative implementation is to use a variation of the above Plack::Builder template:
use Plack::Builder;
use Dancer ':syntax';
use Dancer::Handler;
use lib 'lib';
my $app1 = sub {
setting appdir => '/home/dotcloud/current';
load_app "My::App";
Dancer::App->set_running_app("My::App");
my $env = shift;
Dancer::Handler->init_request_headers($env);
my $req = Dancer::Request->new(env => $env);
Dancer->dance($req);
};
builder {
mount "/app1" => $app1;
};
This also supports hosting multiple apps, but you probably also need to specify the
specific Environment configuration to use in your application.
When mounting under a path on dotcloud, as in the above example, always create links using
the "uri_for()" method for Dancer routes, and a "uri_base" variable for static content as
shown in Dancer::Cookbook. This means whatever base path your app is mounted under, links
and form submissions will continue to work.
Creating a service
You can turn your app into proper service running in background using one of the following
examples:
Using Ubic
Ubic is a polymorphic 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);
__PACKAGE__->new(
server => 'Starman',
app => '/path/to/your/application/app.pl',
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.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/
<Location /mywebapp/>
RequestHeader set Request-Base /mywebapp
</Location>
HTTP header "Request-Base" is taken into account by Dancer, only when "behind_proxy"
setting is set to true.
It is important for you to note that the Apache2 modules mod_headers, mod_proxy and
mod_proxy_http must be enabled.
a2enmod headers
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_set_header X-Forwarded-Proto $scheme;
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
Plackup Chef Cookbook
A psgi chef cookbook supporting Dancer (as well as Catalyst) written by Alexey Melezhik is
available at <http://community.opscode.com/cookbooks/psgi>.
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 /websites/myapp.example.com>
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>
NOTE: Only a single Dancer application can be deployed using the "Plack::Handler::Apache2"
method. Multiple Dancer applications will not work properly (The routes will be mixed-up
between the applications).
It's recommended to start each app with "plackup" using your favorite server (Starman, for
example) and then put a web server (Apache, Nginx, Perlbal, etc.) as a frontend server for
both apps using reverse proxy (HTTP based, no fastcgi).
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 5000 bin/app.pl
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.pl