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Manual Reference Pages  -  DANCER2::MANUAL::DEPLOYMENT (3)

.ds Aq ’

NAME

Dancer2::Manual::Deployment - common ways to put your Dancer app into use

CONTENTS

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 <B> not B> 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/



<B>Please note: B> 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 <B>/applicationB> path to the path <B>/B> 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 youd 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.

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perl v5.20.3 DANCER2::MANUAL::DEPLOYMENT (3) 2016-01-22

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