[DOC] provided an example of configuration involving URL switching.

examples/haproxy-small.spec

@@ -62,7 +62,7 @@ fi
 
 %files
 %defattr(-,root,root)
-%doc CHANGELOG TODO examples doc/haproxy-en.txt doc/haproxy-fr.txt doc/architecture.txt
+%doc CHANGELOG TODO examples doc/haproxy-en.txt doc/haproxy-fr.txt doc/architecture.txt examples/url-switching.cfg
 %attr(0755,root,root) %{_sbindir}/%{name}
 %dir %{_sysconfdir}/%{name}
 %attr(0644,root,root) %config(noreplace) %{_sysconfdir}/%{name}/%{name}.cfg

examples/haproxy.spec

@@ -64,7 +64,7 @@ fi
 
 %files
 %defattr(-,root,root)
-%doc CHANGELOG TODO examples doc/haproxy-en.txt doc/haproxy-fr.txt doc/architecture.txt
+%doc CHANGELOG TODO examples doc/haproxy-en.txt doc/haproxy-fr.txt doc/architecture.txt examples/url-switching.cfg
 %attr(0755,root,root) %{_sbindir}/%{name}
 %dir %{_sysconfdir}/%{name}
 %attr(0644,root,root) %config(noreplace) %{_sysconfdir}/%{name}/%{name}.cfg

examples/url-switching.cfg

@@ -0,0 +1,120 @@
+#
+# This configuration can be used as an example of how URL-switching may be
+# implemented with current haproxy versions.
+#
+# Right now (version 1.2), haproxy can only select a server based on the cookie
+# provided by the client. While this may sound limitated, it is yet possible to
+# combine this feature to rewrites to provide full URL-switching capabilities.
+#
+# For this, we have to chain 3 levels :
+#  - front-end : will match the expected URIs and assign a cookie accordingly ;
+#                it uses regexps and could match on anything else (Host:,
+#                cookies, ...)
+#  - switch    : will select a back-end depending on the cookie above
+#  - back-ends : will perform the load balancing between multiple servers for
+#                the same group. Note that this level can be omitted if there
+#                is only one server for each backend.
+#
+# Logging is performed at the lower level (back-ends) so that local server
+# problems can be identified quickly with the timers. The client's IP is
+# propagated in the X-Forwarded-For: header.
+#
+
+global
+	daemon
+	maxconn 6000      # warning: this has to be 3 times the expected value!
+	log 192.168.0.1 local0
+
+defaults
+	mode	http
+	balance roundrobin
+	option	dontlognull
+	option	httpclose
+	retries	1
+	redispatch
+	maxconn		2000
+	contimeout	5000
+	clitimeout	50000
+	srvtimeout	50000
+
+#
+# This is the instance the client connects to.
+#
+listen	frontend 10.20.30.40:80
+	option forwardfor		# add 'X-Forwarded-For: IP'
+
+	# remove an eventual 'backend' cookie the client might have sent
+	reqidel ^Cookie:\ backend=
+
+	# add cookie 'backend=2' for any HTTP method followed by
+	#  '/img' only or '/img/' followed by anything.
+	reqirep ^[^:\ ]*\ /img[/\ ].* \0\nCookie:\ backend=2
+
+	# add cookie 'backend=3' for any HTTP method followed by
+	#  '/home' only or '/home/' followed by anything.
+	reqirep ^[^:\ ]*\ /home[/\ ].*   \0\nCookie:\ backend=3
+
+	# send everything to next stage
+	server	switch 127.0.0.2:8000
+
+
+#
+# This instance is only seen by the 'frontend' instance above. It receives all
+# of its traffic.
+#
+listen switch 127.0.0.2:8000
+	# cookie name 'backend' inserted by the 'frontend' instance above
+	cookie backend
+
+	# default server 'backend1' gets the default traffic.
+	server backend1 127.0.0.3:8001
+
+	# those servers get traffic only if their cookie is present because
+	# they are tagged 'backup'.
+	server backend2 127.0.0.3:8002 cookie 2 backup
+	server backend3 127.0.0.3:8003 cookie 3 backup
+
+#
+# Backend 1 for dynamic contents.
+# It is made of 4 apache servers which we can test thanks to a CGI script.
+#
+listen	backend1 127.0.0.3:8001
+	log	global
+	option	httplog
+	capture request header X-Forwarded-For len 15
+	option	httpchk /cgi-bin/testhost.pl
+	server	apache1 192.168.1.1:80 maxconn 100 check inter 2000 fall 3
+	server	apache2 192.168.1.2:80 maxconn 100 check inter 2000 fall 3
+	server	apache3 192.168.1.3:80 maxconn 100 check inter 2000 fall 3
+	server	apache4 192.168.1.4:80 maxconn 100 check inter 2000 fall 3
+
+#
+# backend 2 for images (/img).
+# It is made of 3 Tux servers which we test by requesting the /img/logo.png
+# file which should be present when file-systems are mounted.
+#
+listen	backend2 127.0.0.3:8002
+	log	global
+	option	httplog
+	capture request header X-Forwarded-For len 15
+	option	httpchk /img/logo.png
+	server	tux5 192.168.1.5:80 check inter 2000 fall 3
+	server	tux6 192.168.1.6:80 check inter 2000 fall 3
+	server	tux7 192.168.1.7:80 check inter 2000 fall 3
+
+#
+# backend 3 for home directories (/home). These are the same machines as for
+# dynamic content, except that a different server is bound to another port.
+# We test the service by checking that the file "/home/webmaster/started"
+# exists.
+#
+listen	backend3 127.0.0.3:8003
+	log	global
+	option	httplog
+	capture request header X-Forwarded-For len 15
+	option	httpchk /home/webmaster/started
+	server	light1 192.168.1.1:8080 check inter 2000 fall 3
+	server	light2 192.168.1.2:8080 check inter 2000 fall 3
+	server	light3 192.168.1.3:8080 check inter 2000 fall 3
+	server	light4 192.168.1.4:8080 check inter 2000 fall 3
+