Deploy a Play! Framework Application behind nginx -> haproxy -> netty (Play2 core) for transient upgrading. This setup fully supports Websockets in almost any variation. - But most importantly uses 2 instances minimum to allow seamless upgrade. Prepare the instances with "cd app/instances/$instance && ~/app/play/play clean compile stage"

app.env.PLAY_OPTS

fooapp@srv:~$ cat app/env/PLAY_OPTS 

export DATABASE_URL="jdbc:postgresql://127.0.0.1/foobar"

# We could wire a different configuration file here
# or set up a different database on the fly
export PLAY_OPTS="-DapplyEvolutions.default=true -DapplyDownEvolutions.default=true -Ddb.default.url="$DATABASE_URL" -Ddb.default.user=fooapp -Ddb.default.password=fooapppw -Ddb.default.driver=org.postgresql.Driver"

daemontools-playframework-run-script.sh

#!/bin/bash

# These environment variables are sometimes needed by the running daemons
export USER=fooapp
export HOME=/home/fooapp

# Include the user-specific profile, it's actually called .profile on debian.
$HOME/.profile

# You can load ENV-Vars from a file.
# I load $PLAY_OPTS from it to read database configuration
# and evolutions settings
source "$HOME/app/env/PLAY_OPTS"

# Now let's go!
# New Relic Agent is loaded as well from a known place
exec /home/fooapp/app/instances/alpha/target/universal/stage/bin/fooapp -J-javaagent:/home/fooapp/app/lib/newrelic/newrelic.jar -Dhttp.port=62002 "$PLAY_OPTS" 2>&1

dir-structure

# There's more! Common structure ensures easy management through some scripts in ~/app/bin,
# ENV-var files in ~/app/env, a git repo in ~/app/src, Play in ~/app/play, libs, configs for daemontools daemons in ~/app/etc
# and most importantly at least two play instances to minimize downtime.
fooapp@serv:~$ tree app -L 2
app
├── bin
│   ├── control
│   └── manage
├── downloads
│   └── play-2.2.2.zip
├── env
│   └── PLAY_OPTS
├── etc
│   └── haproxy
├── instances
│   ├── alpha
│   └── beta
├── lib
│   └── newrelic
├── play
│   ├── CONTRIBUTING.md
│   ├── framework
│   ├── play
│   ├── play.bat
│   ├── README.md
│   ├── repository
│   └── samples
├── src
│   ├── branches
│   ├── config
│   ├── description
│   ├── HEAD
│   ├── hooks
│   ├── info
│   ├── objects
│   └── refs
└── templates
    ├── haproxy.cfg.tpl
    └── post-receive.tpl

21 directories, 13 files

haproxy.cfg

# I run haproxy with DJBs daemontools, so no daemon here
global
        log 127.0.0.1   local0
        log 127.0.0.1   local1 notice
        #log loghost    local0 info
        maxconn 4096
        #debug
        #quiet
        user fooapp
        group fooapp

defaults
        log     global
        mode    http
        option  httplog
        option  dontlognull
        retries 3
        option redispatch
        maxconn 2000
        contimeout      5000
        clitimeout      50000
        srvtimeout      50000

listen fooapp-master 127.0.0.1:62000
       mode http
       stats enable
       # change this, or disable stats!
       stats auth user:statspw
       balance leastconn
       option httpclose
       option forwardfor
       option httpchk GET / HTTP/1.0
       server alpha 127.0.0.1:62002 check
       server beta 127.0.0.1:62003 check

nginx.site1.conf

server {
	server_name fooapp.org;
	listen server.ip;
	listen [ip:v6:ip] default_server ipv6only=on;
	root /home/appuser/public_html;
	index index.html index.htm index.php;
	access_log /var/log/nginx/fooapp_access_log;
	error_log /var/log/nginx/fooapp_error_log;
	ssl_certificate /home/fooapp/ssl.cert;
	ssl_certificate_key /home/fooapp/ssl.key;
	
	# Little caveat: on upgrade of alpha (which involves the "clean" task,
	# this would fail. See fx http://stackoverflow.com/questions/5555419/nginx-search-for-static-content-in-multiple-directories
	# for a possible solution
	location /assets {
                root /home/fooapp/app/instances/alpha/target/scala-2.10/classes/public;
		            rewrite ^/assets(/.*)$ $1 break;
        }
	location / {
    # haproxy balances on port 62000
		proxy_pass http://127.0.0.1:62000;
		proxy_redirect      off;
		proxy_set_header    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_http_version 1.1;
		proxy_set_header Upgrade $http_upgrade;
		proxy_set_header Connection "upgrade";
		
		proxy_buffering     off;

		proxy_connect_timeout 43200000;
		proxy_read_timeout    43200000;
		proxy_send_timeout    43200000;
	}
}