Put your application in production

Here some simple tips to optimize your application for production.

application.conf

First off, the best way to specify production mode is to give a specific ID to your production framework. Let’s pick production as an example. Refer manage application.conf in several environments to see how.

Set the framework in prod mode:

%production.application.mode=prod

In this mode, the framework will pre-compile all Java sources and templates. If an error is found at this step, the application will not start. Source modifications will not be hot reloaded.

Define a real database:

If you have used a development database (either db=mem or db=fs), you should configure a more robust database engine:

%production.db.url=jdbc:mysql://localhost/prod
%production.db.driver=com.mysql.jdbc.Driver
%production.db.user=root
%production.db.pass=1515312

Disable JPA automatic schema update:

If you have used the automatic schema update feature provided by Hibernate, you should disable this feature for production.

For your production server, it’s usually a bad idea to let Hibernate automatically ALTER your production database’s schema and data…

The initial deployment is potentially a different issue. In this case only specify:

%production.jpa.ddl=create

Define a secure secret key:

The Play secret key is used to secure cryptographic functions, like the session signature. Your application must keep this key very secret.

%production.application.secret=c12d1c59af499d20f4955d07255ed8ea333

You can use the play secret command to generate a new secure and random key (at least on a ‘real’ OS). If you plan to distribute your application to several servers, remember to use the same key for all application instances!

Logging configuration

For production it’s a good idea to use rolling log files. Do not send logging to the Console, since it will be written to the logs/system.out file and it will grow without bound!

Create a custom log4j.properties in the conf/ directory:

log4j.rootLogger=ERROR, Rolling
 
log4j.logger.play=INFO
 
# Rolling files
log4j.appender.Rolling=org.apache.log4j.RollingFileAppender
log4j.appender.Rolling.File=application.log
log4j.appender.Rolling.MaxFileSize=1MB
log4j.appender.Rolling.MaxBackupIndex=100
log4j.appender.Rolling.layout=org.apache.log4j.PatternLayout
log4j.appender.Rolling.layout.ConversionPattern=%d{ABSOLUTE} %-5p ~ %m%n

Front-end HTTP server

You can easily deploy your application as a stand-alone server by setting the application HTTP port to 80:

%production.http.port=80

But if you plan to host several applications in the same server or load balance several instances of your application for scalability or fault tolerance, you can use a front-end HTTP server.

Note that using a front-end HTTP server will never give you better performance than using Play server directly!

Set-up with lighttpd

This example shows you how to configure lighttpd as a front-end web server. Note that you can do the same with Apache, but if you only need virtual hosting or load balancing, lighttpd is a very good choice and much easier to configure!

The /etc/lighttpd/lighttpd.conf file should define things like this:

server.modules = (
      "mod_access",
      "mod_proxy",
      "mod_accesslog" 
)
…
$HTTP["host"] =~ "www.myapp.com" {
    proxy.balance = "round-robin" proxy.server = ( "/" =>
        ( ( "host" => "127.0.0.1", "port" => 9000 ) ) )
}
 
$HTTP["host"] =~ "www.loadbalancedapp.com" {
    proxy.balance = "round-robin" proxy.server = ( "/" => ( 
          ( "host" => "127.0.0.1", "port" => 9000 ), 
          ( "host" => "127.0.0.1", "port" => 9001 ) ) 
    )
}

Set-up with Apache

The example below shows a simple set-up with Apache httpd server running in front of a standard Play configuration.

LoadModule proxy_module modules/mod_proxy.so
…
<VirtualHost *:80>
  ProxyPreserveHost On
  ServerName www.loadbalancedapp.com
  ProxyPass / http://127.0.0.1:9000/
  ProxyPassReverse / http://127.0.0.1:9000/
</VirtualHost>

Apache as a front proxy to allow transparent upgrade of your application

The basic idea is to run two Play instances of your web application and let the front-end proxy load-balance them. In case one is not available, it will forward all the requests to the available one.

Let’s start the same Play application two times: one on port 9999 and one on port 9998.

Make a copy of the application and edit the application.conf in the conf directory to change the port numbers.

For each web application directory:

play start mysuperwebapp

Now, let’s configure our Apache web server to have a load balancer.

In Apache, I have the following configuration:

<VirtualHost mysuperwebapp.com:80>
  ServerName mysuperwebapp.com
  <Location /balancer-manager>
    SetHandler balancer-manager
    Order Deny,Allow
    Deny from all
    Allow from .mysuperwebapp.com
  </Location>
  <Proxy balancer://mycluster>
    BalancerMember http://localhost:9999
    BalancerMember http://localhost:9998 status=+H
  </Proxy>
  <Proxy *>
    Order Allow,Deny
    Allow From All
  </Proxy>
  ProxyPreserveHost On
  ProxyPass /balancer-manager !
  ProxyPass / balancer://mycluster/
  ProxyPassReverse / http://localhost:9999/
  ProxyPassReverse / http://localhost:9998/
</VirtualHost>

The important part is balancer://mycluster. This declares a load balancer. The +H option means that the second Play application is on stand-by. But you can also instruct it to load-balance.

Every time you want to upgrade mysuperwebapp, here is what you need to do:

play stop mysuperwebapp1

The load-balancer then forwards everything to mysuperwebapp2. In the meantime update mysuperwebapp1. Once you are done:

play start mysuperwebapp1

You can now safely update mysuperwebapp2.

Apache also provides a way to view the status of your cluster. Simply point your browser to /balancer-manager to view the current status of your clusters.

Because Play is completely stateless you don’t have to manage sessions between the 2 clusters. You can actually easily scale to more than 2 Play instances.

Advanced proxy settings

When using an HTTP frontal server, request addresses are seen as coming from the HTTP server. In a usual set-up, where you both have the Play app and the proxy running on the same machine, the Play app will see the requests coming from 127.0.0.1.

Proxy servers can add a specific header to the request to tell the proxied application where the request came from. Most web servers will add an X-Forwarded-For header with the remote client IP address as first argument. If you enable the forward support in the XForwardedSupport configuration, Play will change the request.remoteAddress from the proxy’s IP to the client’s IP. You have to list the IP addresses of your proxy servers for this to work.

However, the host header is untouched, it’ll remain issued by the proxy. If you use Apache 2.x, you can add a directive like:

ProxyPreserveHost on

The host: header will be the original host request header issued by the client. By combining theses two techniques, your app will appear to be directly exposed.

HTTPS configuration

The built-in server supports the HTTPS protocol, which you can use it in production. It supports certificate management, either via the classical Java keystore or simple cert and key files. To start an HTTPS connector for your application, just declare the https.port configuration property in your application.conf file:

http.port=9000
https.port=9443

You need to put your certificates in the conf directory. Play supports X509 certificates and keystore certificates. The X509 certificates must be named as follows:
host.cert for the certificate and host.key for the key. If you are using keystore, then, by default it should be named certificate.jks.

If you are using X509 certificates, then the following parameters can be configured in your application.conf file:

# X509 certificates
certificate.key.file=conf/host.key
certificate.file=conf/host.cert
# In case your key file is password protected
certificate.password=secret
trustmanager.algorithm=JKS

If you are using keystore:

keystore.algorithm=JKS
keystore.password=secret
keystore.file=conf/certificate.jks

Note that the values above are the default values.

You can generate self-signed certificates using openssl:

openssl genrsa 1024 > host.key
openssl req -new -x509 -nodes -sha1 -days 365 -key host.key > host.cert

If you are using the Java keystore mechanism, then the following properties can be configured in your application.conf file:

# Keystore 
ssl.KeyManagerFactory.algorithm=SunX509
trustmanager.algorithm=JKS
keystore.password=secret
keystore.file=certificate.jks

The values above are the default values.

Deploying Without Python

Python is installed by default on most Unix machines, and a Windows version is embedded with Play. However there may be cases where you need to deploy an application on a server without any Python executable.

For that, a build.xml file providing limited functionalities is provided with Play applications.

From the application folder, you can start the server using:

ant start -Dplay.path=/path/to/playdirectory

Warning: using the play command the output will be redirected to System.out; however using Ant the standard output is not accessible. It is necessary to provide a Log4j properties file where you specify a file appended.

To stop the server:

ant stop -Dplay.path=/path/to/playdirectory

Note that you can also specify the path to Play framework in an environment variable or directly in your application’s build.xml.

Continuing the discussion

Next: Deployment options.