This document discusses deploying Plack web applications. It begins with an overview of the PSGI specification and how it allows various web frameworks like Catalyst and Dancer to run on different web servers through a common interface. It then discusses various options for the server environment including standalone HTTP servers like Starman and FastCGI servers. Finally, it covers useful Plack middleware for application environments, including modules for rate limiting, caching, authentication, and more.

1. Deploying Plack
Web Applications
Tatsuhiko Miyagawa
O’Reilly OSCON 2011

2. Me
• Tatsuhiko Miyagawa
• @miyagawa
• Lives in San Francisco, CA
• Software Engineer, DotCloud

3. My Software
• Plack
• PSGI
• cpanminus
• carton (NEW!)

4. PSGI

5. PSGI in 3 min.

6. # PSGI
my $app = sub {
my $env = shift;
return [
200,
[ ‘Content‐Type’, ‘text/plain’ ],
[ ‘Hello World’ ],
];
};

7. Catalyst CGI::App Jifty Mojolicious Dancer
Plack::Middleware
PSGI
Plack::Handler::* (CGI, FCGI, Apache)
Apache lighttpd HTTP::Server::PSGI mod_psgi Perlbal
Starman Twiggy uWSGI Corona Feersum

8. Mason CGI::Application Jifty Catalyst
Mason::CGIHandler
CGI.pm Catalyst::Engine
mod_perl CGI fastcgi
HTTP::Server
::Simple Apache IIS lighttpd nginx

9. Catalyst CGI::App Jifty Mojolicious Dancer
Plack::Middleware
PSGI
Plack::Handler::* (CGI, FCGI, Apache)
Apache lighttpd HTTP::Server::PSGI mod_psgi Perlbal
Starman Twiggy uWSGI Corona Feersum

11. Momentum

12. Catalyst 5.9
Built-in PSGI/Plack support

13. CGI::Application 4.5
Built-in PSGI support

14. Dancer, Mojolicious

15. 20+
Web Frameworks

16. 25+
Web Servers/Handlers

17. 150+
Plack Middleware

19. Cloud (PaaS)

20. Still not convinced?

21. “FastCGI is good enough”?
http://xrl.us/psgireddit

22. Deploying Plack
Web applications

23. 1)
Server Environment

24. 2)
Code Deployment

25. 3)
Application Environment

26. 1)
Server Environment

27. Writing a PSGI app?

28. Maypole Mason Mojolicious Sledge Catalyst Spoon
PageKit AxKit Egg Gantry Continuity Solstice
Mojolicious Tripletail Konstrukt Reaction Jifty WebGUI
OpenInteract Squatting Dancer CGI::Application
Ark Angelos Noe Schenker Tatsumaki Amon
Apache2::WebApp Web::Simple Apache2::REST
SweetPea Hydrant Titanium

29. Pick one.
Whichever you like.

30. Deploying a PSGI app?

31. HTTP::Server::PSGI CGI FastCGI mod_perl
mod_perl2 Fastpass Starman Starlet Twiggy
HTTP::Server::Simple::PSGI Feersum Corona
mod_psgi evpsgi nginx_psgi Pelrbal uWSGI
FCGI::EV AnyEvent::FCGI AnyEvent::HTTPD
Prack/nack Mongrel2

32. Pick one.
Whichever you like.

33. “I don’t know which
I like the most.”

34. Some hints

35. Based on my experience
and your experience

36. HTTP::Server::PSGI
• Plack Built-in
• Pure Perl
• Single-process, cross platform
• Experimental IPv6, SSL
• Automatic reloading with -r

37. HTTP::Server::PSGI
• Plack Built-in
• Pure Perl
• Single-process, cross platform
• Experimental IPv6, SSL
• Automatic reloading with -r
Great for development and testing

38. HTTP::Server::Simple::PSGI
• Zero non-core dependencies (other than
HTTP::Server::Simple)
• Single-process, extensible with H::S::S
• Works on 5.005_*
• Dancer’s default web server

39. HTTP::Server::Simple::PSGI
• Zero non-core dependencies (other than
HTTP::Server::Simple)
• Single-process, extensible with H::S::S
• Works on 5.005_*
• Dancer’s default web server
Great for embedding e.g. Android

40. CGI
• Plack::Handler::CGI
• Almost universally available
• Quite slow and inefficient
• Reasonably easy to run from the shell

41. CGI
• Plack::Handler::CGI
• Almost universally available
• Quite slow and inefficient
• Reasonably easy to run from the shell
Last resort for Win32/IIS
laptop web apps

42. mod_perl
• Plack::Handler::Apache[12]
• Lots of hooks and Apache modules
• Porting from mod_perl to PSGI might be
tricky. (There are some tools/attempts)

43. mod_perl
• Plack::Handler::Apache[12]
• Lots of hooks and Apache modules
• Porting from mod_perl to PSGI might be
tricky. (There are some tools/attempts)
Not recommended unless you’ve
hugely invested in mod_perl

44. Perlbal::Plugin::PSGI
• Pure perl load balancer
• LiveJournal, TypePad etc.
• Reproxying, Plugins etc.
• Danga::Socket (non-blocking)

45. Perlbal::Plugin::PSGI
• Pure perl load balancer
• LiveJournal, TypePad etc.
• Reproxying, Plugins etc.
• Danga::Socket (non-blocking)
Considered EXPERIMENTAL

46. mod_psgi
• Apache module to run PSGI apps
• No mod_perl hooks
• Just persistent PSGI apps
• Simpler

47. mod_psgi
• Apache module to run PSGI apps
• No mod_perl hooks
• Just persistent PSGI apps
• Simpler
Considered EXPERIMENTAL

48. nginx_mod_psgi
• nginx native PSGI extension
• https://github.com/yko/ngx_mod_psgi
• Pretty new

49. nginx_mod_psgi
• nginx native PSGI extension
• https://github.com/yko/ngx_mod_psgi
• Pretty new
Considered EXPERIMENTAL

50. Mongrel2
• Zed Shaw
• ZeroMQ
• Pretty cool stuff
• lestrrat (Plack::Handler::Mongrel2)
• jockway (AnyEvent::Mongrel2)

51. Mongrel2
• Zed Shaw
• ZeroMQ
• Pretty cool stuff
• lestrrat (Plack::Handler::Mongrel2)
• jockway (AnyEvent::Mongrel2)
Considered EXPERIMENTAL

52. Recommended Servers?

53. Standalone HTTP Servers

54. FastCGI daemons

55. Put it behind the frontend
(nginx etc.)

56. Starman
• Standalone HTTP
• Prefork, app preloading
• Dynamic process management
• TCP/UNIX Sockets
• Partial HTTP/1.1 support
• Graceful restarts

57. Starman (cont.)
• The Lacuna Expanse
• perl.org
• cpanratings.perl.org
• etc.

58. Starlet
• Standalone HTTP server
• Prefork, app preloading
• HTTP/1.0
• Max/min spare workers
• Hot deploy via Server::Starter

59. Starlet (cont.)
• Livedoor
• Hatena
• etc.

60. Twiggy
• Standalone HTTP server
• AnyEvent based
• Tiny memory footprint

61. Twiggy (cont.)
• mixi
• SAY Media
• beta.metacpan.org

62. Feersum
• Standalone HTTP server
• EV.xs
• picohttpparser (C library)
• AnyEvent compatible
• Lighting fast

63. Plack::Handler::FCGI
• Standalone FastCGI daemon
(or web server mode)
• Preforking
• TCP/UNIX sockets
• FCGI.xs
• Little bit of process management

64. fastpass
• github.com/miyagawa/fastpass
• Standalone FastCGI daemon
• preforking, dynamic process management
• Net::FastCGI (no XS)
• TCP/UNIX sockets

65. FCGI::EV/AE::FCGI
• Standalone FastCGI daemon
• EV/AnyEvent based
• asynchronous, non-blocking

66. uWSGI
• FastCGI-like protocol
• Optimized for *SGI
• built-in nginx/cherokee support
• AnyEvent support in the works
• Lots of configurations
• harakiri mode

67. uWSGI (cont.)
• DotCloud.com
(more server types coming!)

68. Proc. UNIX Graceful
Proto, Prefork Async TCP/IP XS/Perl
Mgmt. Sockets Restarts
Starman HTTP ✔ ✔ ✔ ✔ ✔ XS
Starlet HTTP ✔ ✔ ✔ ✔ XS/PP
Twiggy HTTP ✔ ✔ ✔ XS/PP
Feersum HTTP ✔ ✔ XS
FastCGI FCGI ✔ ✔ ✔ ✔ XS
fastpass FCGI ✔ ✔ ✔ ✔ ✔ PP
AE::FCGI FCGI ✔ ✔ ✔ PP
FCGI::EV FCGI ✔ ✔ ✔ XS
uWSGI uWSGI ✔ ✔ ✔ ✔ ✔ C/XS

69. General guideline:

70. “Traditional” MVC apps?
Lots of RDBMS queries?
Coming from mod_perl?

71. Preforking servers
Put it behind nginx.

72. Lots of I/O bound requests?
New app or can rewrite to use AE?
Resource limited environment?

73. Asynchronous servers
Twiggy or Feersum.

74. HTTP or FastCGI?

75. HTTP Standalone☺
• Put it behind frontend (nginx, lighttpd)
• Most web servers support reverse proxy
• As well as load balancers (perlbal, varnish)
• Easy for human to debug and test
• nginx + unix socket workers work well

76. HTTP Standalone ☹
• You may have to configure X-Forwarded-*
and ReverseProxy middleware
• Keep-alives can be problematic in dumb
servers like mod_proxy on apache2
• Path mismatch on frontend/backend could
cause headaches

77. FastCGI ☺
• Many web servers support fastcgi
• No need for X-Forwarded-* configuration
• Potentially faster binary protocol between
web server and app server
• “Hot deploy” via UNIX sockets

78. FastCGI ☹
• Binary protocol, may not be easy to debug
• Requires C/XS (but see fastpass)
• Hard to get SCRIPT_NAME/PATH_INFO
right (e.g. lighttpd, mod_fcgid)

79. Questions/Suggestions?

80. 2)
Code Deployment

81. Conventions = good.

82. Web app convention:

83. 1) PSGI endpoint

84. 2) CPAN dependencies

85. 1) app.psgi
2) Makefile.PL

86. > git commit ‐m ‘releasing v1.0.0’
> git tag v1.0.0
> git push ‐‐tags
> (checking out code)
> cpanm ‐‐installdeps .
> (restart app servers gracefully)

87. cpanm --installdeps .

88. <3

89. Problem

90. Pulls the latest versions
of CPAN today.

91. Many solutions:
Shipwright, MyCPAN, orepan, DPAN

92. Carton
inspired by bundler

93. Carton
• App-specific local environment (local::lib)
• Dep-tree analysis, including versions.
• Single-file,VCS friendly
• Freezing/locking versions
• Recreates mirror on deploy
• Conservative Updates

94. > carton install
> git commit ‐m ‘releasing v1.0.0’
carton.lock Makefile.PL
> git tag v1.0.0
> git push ‐‐tags
> (checking out code)
> carton install
> (restart app servers gracefully)

95. dotCloud will do
all of this for you :)
DISCLAIMER: I work for dotCloud.

96. github.com/miyagawa/carton

97. 3)
Application Environment

98. Useful middleware
for deployments

100. SizeLimit
Port of Apache::SizeLimit
Supported by Starman, Starlet, uWSGI

101. use Plack::Builder;
builder {
enable “SizeLimit”,
max_unshared_size_in_kb => 4096,
check_every_n_requests => 5;
$app;
}

102. ServerStatus::Lite
Port of mod_status
Starlet, Starman

103. use Plack::Builder;
builder {
enable “ServerStatus::Lite”,
path => ‘/server‐status’;
$app;
}

104. Runtime
Adds X-Runtime: header

105. use Plack::Builder;
builder {
enable “Runtime”;
$app;
}

106. use Plack::Builder;
builder {
enable “Runtime”;
$app;
}

107. % curl ‐I http://localhost:5000/
HTTP/1.0 200 OK
Server: HTTP::Server::PSGI
X‐Runtime: 0.00029

108. ErrorDocument
Customize error pages
500/503/404 etc.

109. use Plack::Builder;
builder {
enable “ErrorDocument”,
500 => ‘/home/www/errors/500.html’;
$app;
};

110. Throttle
Rate-limiting framework

111. use Plack::Builder;
builder {
enable “Throttle::Hourly”,
max => 200,
backend => ...,
path => qr!^/api!;
$app;
}

112. Expires
Port of mod_expires
Cache static files on proxy/clients

113. use Plack::Builder;
builder {
enable “Expires”,
content_type => qr!^image/!,
expires => ‘access plus 3 months’;
$app;
};

114. Rewrite
mod_rewrite-ish URL rewriting
pure perl syntax

115. use Plack::Builder;
builder {
enable ‘Rewrite’, rules => sub {
s{^/here}{/there};
return 301 if s{^/foo/}{/bar/};
return 201 if $_ eq ‘/favicon.ico’;
return 503 if ‐e ‘/tmp/maint.txt’;
};
$app;
}

116. Auth::Basic/Digest
Add Basic authentication
with any Auth::Simple backends

117. use Plack::Builder;
use Authen::Simple::Kerberos;
my $auth = Authen::Simple::Kerberos‐>new(
realm => ‘REALM.MYCOMPANY.COM’,
);
builder {
enable “Auth::Basic”,
authenticator => $auth;
$app;
};

118. PSGI Deployment
Survey

119. ~100 responses
Thank you!

120. What category describes
your apps best?

121. Intranet
9%
Personal
21%
Small to mid-scale
49%
Large scale
21%

122. Where is it hosted?

123. VPS Colocation Own Data Center Enterprise Home Cloud

124. Operating Systems?

125. Ubuntu
Debian
CentOS
RHEL
Linux
FreeBSD
Mac OS X
Windows
Solaris
0 10 20 30 40

126. Perl versions?

127. 60
45
30
15
0
“5.8” “5.10” “5.12” “5.14”

128. Web Frameworks?

129. (in-house)
Catalyst
Mojolicious
Dancer
CGI::Application
Tatsumaki
Amon2
Mason
0 10 20 30 40

130. When did you migrate
or start using PSGI?

131. 2009 Year 2010 Q2 2010 Q4 2011 Q2 Future

132. Which PSGI server?

133. Starman
Starlet
Twiggy
Plack::Handler::FCGI
mod_perl 2
HTTP::Server::PSGI
H::S::Simple::PSGI
CGI
Feersum
uWSGI
mod_perl 1.3
0 15 30 45 60

134. FastCGI web servers
mod_fcgid
8%
lighttpd
20% nginx
40%
mod_fastcgi
33%

135. Frontend web servers
nginx
mod_proxy
perlbal
Varnish
lighttpd
Squid

136. How did you measure the right # of
servers and worker processes?

137. Guess
Defaults 7%
6%
by RAM
by CPU 40%
19%
by req. time
27%

138. How do you keep
logs of your apps?

139. Log4perl
daemontools
syslog
logrotate
Log::Dispatch
Log::Minimal
supervisor
runit
Others

140. Results will be posted on
http://blog.plackperl.org/

141. One more thing...

142. REPL
InteractiveDebugger

143. Thanks!
Check out Booth 527
for FREE DotCloud T-shirt