The document discusses Varnish, an open source HTTP accelerator. It provides an overview of caching and why it is useful, explaining how Varnish can be used as a reverse proxy and caching layer in front of a web server. The document then covers setup instructions for Varnish, configuring backends, and using Varnishstat to monitor caching statistics and performance metrics.

1. Varnish
in
ac*on
Thijs
Feryn
Evangelist
+32
(0)9
218
79
06
thijs@combellgroup.com
phpDay
Friday
May
13th
2011
Verona,
Italy

2. About
me
I’m
an
evangelist
at
Combell

3. About
me
I’m
a
board
member
at
PHPBenelux

4. I
live
in
the
wonderful
city
of
Bruges
MPBecker
-­‐
Bruges
by
Night
hVp://www.flickr.com/photos/galverson2/3715965933

5. Follow
me
on
TwiVer:
@ThijsFeryn
Give
me
feedback:
hVp://joind.in/3006
Read
my
blog:
hVp://blog.feryn.eu

7. Varnish

8. Varnish
Reverse
proxy?
Caching
proxy?
Loadbalancer?

9. Varnish
HTTP
accelerator
!

10. Caching

11. Caching
Storing
computed
data
for
faster
serving
of
future
requests

12. Basically
Pudng
stuff
in
boxes
for
later
use

13. Why?

14. Protect
your
server

15. In
the
beginning
there
was
...

16. Browser
cache

17. Browser
cache:
expira*on
Expires:
Sun,
25
Jun
2006
14:57:12
Cache-­‐Control:
max-­‐age=86400,
must-­‐revalidate

18. Browser
cache:
valida*on
Last-­‐Modified:
Sun,
25
Jun
2006
14:57:12
GMT
ETag:
“686897696a7c876b7e”

19. Browser
cache:
valida*on
Last-­‐Modified:
Sun,
25
Jun
2006
14:57:12
GMT
ETag:
“686897696a7c876b7e”
Compared
with
the
“If-­‐None-­‐Match”
header.
Throws
“HTTP/1.0
304
Not
Modified”
accordingly

20. Browser
cache:
in
PHP

21. Browser
cache:
in
PHP
<?php
$seconds = 10;
$expires = gmdate('D, j M Y H:i:s T', time() + $seconds);
header("Expires: $expires");
header("Cache-Control: max-age=$seconds, must-revalidate");
?>
<ul>
<li>Current date/time: <?= gmdate('D, j M Y H:i:s T')?></li>
<li>Expires: <?= $expires ?></li>
<li>Cache-control: <?= $seconds?> seconds</li>
</ul>

22. Browser
cache:
in
Apache

23. Browser
cache:
in
Apache
ExpiresAc*ve
on
ExpiresDefault
"access
plus
1
month"
ExpiresDefault
"now
plus
4
weeks"
ExpiresDefault
"modifica*on
plus
30
days"
ExpiresByType
text/html
"access
plus
1
month
15
days
2
hours"

24. Browser
cache
is
your
friend
!

25. Problems
with
browser
cache

26. Problems
with
browser
cache
Mul*ple
standards
Can
be
ignored
by
browser
Force
refresh
Cache
per
client

27. Solu*ons:
use
a
caching/reverse
proxy!
Use
a
caching/reverse
proxy
Varnish
does
that
It’ll
make
your
site
fly!

28. Info
•Website:
h$p://www.varnish-­‐cache.org
•Wiki:
h$p://www.varnish-­‐cache.org/trac/wiki
•Examples:
h$p://www.varnish-­‐cache.org/trac/wiki/VCLExamples
•DocumentaHon
site:
h$p://www.varnish-­‐cache.org/docs/2.1

29. Setup
Varnish

30. Setup
Varnish
curl http://repo.varnish-cache.org/debian/
GPG-key.txt | apt-key add -
echo "deb http://repo.varnish-cache.org/
debian/ $(lsb_release -s -c) varnish-2.1"
>> /etc/apt/sources.list
apt-get update
apt-get install varnish

31. Setup
Varnish
START=yes
DAEMON_OPTS="-a :80
-T localhost:6082
-f /etc/varnish/default.vcl
-s file,/var/lib/varnish/$INSTANCE/
varnish_storage.bin,1G"
In
“/etc/default/varnish”

32. Setup
the
backend

33. Setup
the
backend
Listen 8080
In
“/etc/apache2/ports.conf”

34. Setup
the
backend
backend default {
.host = "127.0.0.1";
.port = "8080";
}
In
“/etc/varnish/default.vcl”

35. Out
of
the
box
Varnish
will
only
...

36. ...
obey
your
caching
headers

37. ...
and
cache
sta*c
files

38. Time
for
ac*on
!

39. Request vcl_recv
Yes Cacheable?
vcl_hash
Yes No
In cache?
No
vcl_hit() vcl_miss()
vcl_fetch()
vcl_deliver()
Response

40. Hits
&
misses

41. Logging
&
sta*s*cs

42. Varnishstat
Real
*me
stats
of
running
varnishd
instance
hVp://www.varnish-­‐cache.org/docs/2.1/reference/varnishstat.html

43. Hitrate
ratio:
10
100
121
Hitrate
avg:
0.5365
0.5287
0.5277
9957
0.00
4.10
Client
connections
accepted
58932
67.92
24.28
Client
requests
received
30483
1.00
12.56
Cache
hits
8592
0.00
3.54
Cache
hits
for
pass
18991
66.92
7.82
Cache
misses
28449
66.92
11.72
Backend
connections
success
22562
66.92
9.30
Backend
connections
reuses
28357
66.92
11.68
Backend
connections
recycles
488
.
.
N
struct
srcaddr
7
.
.
N
active
struct
srcaddr
81
.
.
N
struct
sess_mem
21
.
.
N
struct
sess
4398
.
.
N
struct
object
4401
.
.
N
struct
objecthead
9220
.
.
N
struct
smf
355
.
.
N
small
free
smf
6
.
.
N
large
free
smf
2
.
.
N
struct
vbe_conn
10
.
.
N
struct
bereq
17
.
.
N
worker
threads
28
0.00
0.01
N
worker
threads
created
164
0.00
0.07
N
overflowed
work
requests
1
.
.
N
backends
14608
.
.
N
expired
objects
24113
.
.
N
LRU
moved
objects
53778
66.92
22.16
Objects
sent
with
write
9957
0.00
4.10
Total
Sessions
58935
67.92
24.28
Total
Requests
9458
0.00
3.90
Total
pass
28445
66.92
11.72
Total
fetch
22496844
23506.62
9269.40
Total
header
bytes
606897837
263427.01
250060.91
Total
body
bytes
1384
0.00
0.57
Session
Closed

44. Varnishlog
Display
requests
of
running
varnishd
instance
hVp://www.varnish-­‐cache.org/docs/2.1/reference/varnishlog.html

45. Varnishlog
Notable
tags
• ReqEnd • TxHeader • RxHeader
• ReqStart • TxLostHeader • RxLostHeader
• Hit • TxProtocol • RxProtocol
• Error • TxRequest • RxRequest
• VCL_call • TxResponse • RxResponse
• VCL_return • TxStatus • RxStatus
• VCL_acl • TxURL • RxURL

46. Varnishlog
varnishlog
-­‐c
-­‐o
RxRequest
POST
All
POST
requests

47. Varnishlog
varnishlog
-­‐c
-­‐i
RxHeader
-­‐I
^User-­‐Agent
All
user
agents

48. Varnishlog
varnishlog
-­‐i
TxURL
All
URL’s
that
“missed”

49. Varnishlog
varnishlog
-­‐o
VCL_call
hit
|
grep
RxURL
All
URL’s
that
“hit”

50. Varnishlog
varnishlog
-­‐w
/tmp/yourfile.log
Write
log
to
file
varnishlog
-­‐r
/tmp/yourfile.log
Read
log
from
file

51.
12
SessionOpen
c
172.16.26.1
50396
:8080
12
ReqStart
c
172.16.26.1
50396
668213522
12
RxRequest
c
GET
12
RxURL
c
/test.php
12
RxProtocol
c
HTTP/1.1
12
RxHeader
c
Host:
varnish.dev:8080
12
RxHeader
c
User-­‐Agent:
Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10
12
RxHeader
c
Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,*/
*;q=0.8
12
RxHeader
c
Accept-­‐Language:
nl,en-­‐us;q=0.7,en;q=0.3
12
RxHeader
c
Accept-­‐Encoding:
gzip,deflate
12
RxHeader
c
Accept-­‐Charset:
ISO-­‐8859-­‐1,utf-­‐8;q=0.7,*;q=0.7
12
RxHeader
c
Keep-­‐Alive:
115
12
RxHeader
c
Connection:
keep-­‐alive
12
RxHeader
c
Cookie:
PHPSESSID=2n2pkit81qdgk6k4trf1crft16
12
VCL_call
c
recv
12
VCL_return
c
pass
12
VCL_call
c
hash
12
VCL_return
c
hash
12
VCL_call
c
pass
12
VCL_return
c
pass
14
BackendClose
-­‐
default
14
BackendOpen
b
default
127.0.0.1
34267
127.0.0.1
80
12
Backend
c
14
default
default

52.
14
TxRequest
b
GET
14
TxURL
b
/test.php
14
TxProtocol
b
HTTP/1.1
14
TxHeader
b
Host:
varnish.dev:8080
14
TxHeader
b
User-­‐Agent:
Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10
14
TxHeader
b
Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,*/
*;q=0.8
14
TxHeader
b
Accept-­‐Language:
nl,en-­‐us;q=0.7,en;q=0.3
14
TxHeader
b
Accept-­‐Encoding:
gzip,deflate
14
TxHeader
b
Accept-­‐Charset:
ISO-­‐8859-­‐1,utf-­‐8;q=0.7,*;q=0.7
14
TxHeader
b
Cookie:
PHPSESSID=2n2pkit81qdgk6k4trf1crft16
14
TxHeader
b
X-­‐Forwarded-­‐For:
172.16.26.1
14
TxHeader
b
X-­‐Varnish:
668213522
14
RxProtocol
b
HTTP/1.1
14
RxStatus
b
200
14
RxResponse
b
OK
14
RxHeader
b
Date:
Tue,
19
Oct
2010
12:54:49
GMT
14
RxHeader
b
Server:
Apache/2.2.16
(Ubuntu)
14
RxHeader
b
X-­‐Powered-­‐By:
PHP/5.3.3-­‐1ubuntu9
14
RxHeader
b
Vary:
Accept-­‐Encoding
14
RxHeader
b
Content-­‐Encoding:
gzip
14
RxHeader
b
Content-­‐Length:
36
14
RxHeader
b
Content-­‐Type:
text/html

53.
12
TTL
c
668213522
RFC
120
1287492889
0
0
0
0
12
VCL_call
c
fetch
12
TTL
c
668213522
VCL
10
1287492889
12
VCL_return
c
pass
12
ObjProtocol
c
HTTP/1.1
12
ObjStatus
c
200
12
ObjResponse
c
OK
12
ObjHeader
c
Date:
Tue,
19
Oct
2010
12:54:49
GMT
12
ObjHeader
c
Server:
Apache/2.2.16
(Ubuntu)
12
ObjHeader
c
X-­‐Powered-­‐By:
PHP/5.3.3-­‐1ubuntu9
12
ObjHeader
c
Vary:
Accept-­‐Encoding
12
ObjHeader
c
Content-­‐Encoding:
gzip
12
ObjHeader
c
Content-­‐Type:
text/html
14
Length
b
36
14
BackendReuse
b
default
12
VCL_call
c
deliver
12
VCL_return
c
deliver
12
TxProtocol
c
HTTP/1.1
12
TxStatus
c
200
12
TxResponse
c
OK
12
TxHeader
c
Server:
Apache/2.2.16
(Ubuntu)
12
TxHeader
c
X-­‐Powered-­‐By:
PHP/5.3.3-­‐1ubuntu9
12
TxHeader
c
Vary:
Accept-­‐Encoding
12
TxHeader
c
Content-­‐Encoding:
gzip
12
TxHeader
c
Content-­‐Type:
text/html
12
TxHeader
c
Content-­‐Length:
36
12
TxHeader
c
Date:
Tue,
19
Oct
2010
12:54:49
GMT
12
TxHeader
c
X-­‐Varnish:
668213522
12
TxHeader
c
Age:
0
12
TxHeader
c
Via:
1.1
varnish

54. Varnishtop
Read
memory
logs
and
presents
them
as
a
con*nuously
updated
list
of
commonly
occuring
log
entries
hVp://www.varnish-­‐cache.org/docs/2.1/reference/varnishtop.html

55. Varnishtop
varnishtop
-­‐i
RxHeader
-­‐I
^User-­‐Agent
Get
the
top
user
agents

56. Varnishtop
varnishtop
-­‐i
RxRequest
Get
the
top
request
methods

57. Varnishtop
varnishtop
-­‐i
TxURL
Get
the
top
misses

58. list
length
90
dev
76.42
VCL_return
pass
50.95
RxProtocol
HTTP/1.1
50.95
TxProtocol
HTTP/1.1
27.54
Length
110
25.48
Debug
herding
25.47
RxRequest
GET
25.47
RxHeader
Host:
varnish.dev:8080
25.47
RxHeader
User-­‐Agent:
Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10
25.47
RxHeader
Accept:
text/html,application/xhtml+xml,application/
xml;q=0.9,*/*;q=0.8
25.47
RxHeader
Accept-­‐Language:
nl,en-­‐us;q=0.7,en;q=0.3
25.47
RxHeader
Accept-­‐Encoding:
gzip,deflate
25.47
RxHeader
Accept-­‐Charset:
ISO-­‐8859-­‐1,utf-­‐8;q=0.7,*;q=0.7
25.47
RxHeader
Keep-­‐Alive:
115
25.47
RxHeader
Connection:
keep-­‐alive
25.47
RxHeader
Cookie:
PHPSESSID=2n2pkit81qdgk6k4trf1crft16
25.47
VCL_call
recv
25.47
VCL_call
hash
25.47
VCL_return
hash
25.47
VCL_call
pass
25.47
Backend
14
default
default
25.47
TxRequest
GET
25.47
TxHeader
Host:
varnish.dev:8080
25.47
TxHeader
User-­‐Agent:
Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10
25.47
TxHeader
Accept:
text/html,application/xhtml+xml,application/

59. Varnishncsa
Read
memory
logs
and
presents
them
in
the
Apache
/
NCSA
“combined”
log
format
hVp://www.varnish-­‐cache.org/docs/2.1/reference/varnishncsa.html

60. Varnishncsa
varnishncsa
-­‐D
-­‐a
-­‐w
/var/log/some.log
172.16.26.1
-­‐
-­‐
[19/Oct/2010:16:08:02
+0200]
"GET
hVp://
varnish.dev:8080/
HTTP/1.1"
200
97
"-­‐"
"Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10"
172.16.26.1
-­‐
-­‐
[19/Oct/2010:16:08:10
+0200]
"GET
hVp://
varnish.dev:8080/test.php
HTTP/1.1"
200
36
"-­‐"
"Mozilla/5.0
(Macintosh;
U;
Intel
Mac
OS
X
10.6;
nl;
rv:1.9.2.10)
Gecko/20100914
Firefox/3.6.10"

61. Varnishreplay
The
varnishreplay
u*lity
parses
varnish
logs
and
aVempts
to
reproduce
the
traffic
hVp://www.varnish-­‐cache.org/docs/2.1/reference/varnishreplay.html

62. Varnishreplay
varnishlog
-­‐w
/tmp/yourfile.log
varnishreplay
-­‐r
/tmp/yourfile.log

63. Management
via
telnet

64. Management
via
telnet
root@dev:/#
telnet
localhost
6082
Trying
::1...
Connected
to
localhost.
Escape
character
is
'^]'.
200
154
-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐
Varnish
HTTP
accelerator
CLI.
-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐-­‐
Type
'help'
for
command
list.
Type
'quit'
to
close
CLI
session.

65. Management
via
telnet
Notable
ac*ons
• vcl.load
<configname>
<filename>
• vcl.use
<configname>
• vcl.discard
<configname> Avoid
interrup*on
• vcl.list
• vcl.show
<configname>

66. More
ac*on?

67. Request vcl_recv
Yes Cacheable?
vcl_hash
Yes No
In cache?
No
vcl_hit() vcl_miss()
vcl_fetch()
vcl_deliver()
Response

68. Cache
sta*c
files
sub vcl_recv {
if ( (req.request == "GET" || req.request == "HEAD")
&& req.url ~ ".(png|gif|jpe?g|swf|css|js|html?|sstm)
$" ) {
return(lookup);
} else {
return(pass);
}
}

69. Provide
HIT/MISS
informa*on
sub vcl_deliver {
if (obj.hits > 0) {
set resp.http.X-Cache = "HIT";
} else {
set resp.http.X-Cache = "MISS";
}
}

70. Manipulate
TTL
sub vcl_fetch {
set beresp.ttl = 10s;
}

71. Cache
...
even
with
cookies
sub vcl_recv {
if (req.request == "GET" || req.request ==
"HEAD") {
return (lookup);
}
}
sub vcl_hash {
if (req.http.Cookie) {
set req.hash += req.http.Cookie;
}
}

72. Remove
cookies
sub vcl_recv {
unset req.http.cookie;
}
sub vcl_fetch {
unset beresp.http.set-cookie;
}

73. Remove
Google
Analy*cs
cookies
sub vcl_recv {
if (req.http.Cookie) {
set req.http.Cookie = regsuball
(req.http.Cookie,"(^|; ) *__utm.=[^;]+;?
*","1");
if (req.http.Cookie == "") {
remove req.http.Cookie;
}
}

74. Mul*ple
backends:
hostname
filtering
backend default {
.host = "default.server.com";
.port = "80";
}
backend other {
.host = "other.server.com";
.port = "80";
}
sub vcl_recv {
if(req.http.host ~ "^www."){
set req.backend= default;
} else {
set req.backend = other;
}
}

75. www.example.com example.com
Default backend Other backend

76. Grace
mode
sub vcl_recv {
if (req.backend.healthy) {
set req.grace = 1s;
} else {
set req.grace = 10s;
}
}
Keep
reading
from
cache,
even
when
expired

77. Mul*ple
backends:
health
checks
backend default {
.host = "default.server.com";
.port = "80";
.probe = {
.url = "/";
.timeout = 50 ms;
.interval = 1s;
.window = 2;
.threshold = 2;
}
}

78. Mul*ple
backends:
health
checks
backend other {
.host = "other.server.com";
.port = "80";
.probe = {
.url = "/";
.timeout = 50 ms;
.interval = 1s;
.window = 2;
.threshold = 2;
}
}

79. Mul*ple
backends:
health
checks
sub vcl_recv {
if (req.restarts == 0) {
set req.backend = default;
} else {
set req.backend = other;
}
return(pass);
}
sub vcl_error {
if (obj.status == 503 && req.restarts
< 4) {
restart;
}
}

80. Default backend Other backend

81. Default backend Other backend

82. Loadbalancing
via
directors
director back round-robin {
{.backend = default;}
{.backend = other;}
}
sub vcl_recv {
set req.backend = back;
return(pass);
}

83. 50% 50%
Default backend Other backend

84. Loadbalancing
via
directors
director back random {
{.backend = default; .weight=1;}
{.backend = other; .weight=2;}
}
sub vcl_recv {
set req.backend = back;
return(pass);
}

85. 33% 66%
Default backend Other backend

86. Purging
acl purge_acl {
"localhost";
"1.2.3.4";
"some.host.ext";
}
sub vcl_recv {
if (req.request == "PURGE") {
if (!client.ip ~ purge_acl) {
error 405 "Not allowed.";
}
purge_url(req.url);
error 200 "Purged.";
}
return(lookup);
}
curl
-­‐X
PURGE
hVp://yoursite.com/yourpage

87. Edge
Side
Includes:
the
final
piece
of
the
puzzle

88. header.php
menu.php main.php
footer.php

89. <html>
<body>
<table>
<tr>
<td colspan="2" >
<?php include('header.php') ?>
</td>
</tr>
<tr>
<td><?php include('menu.php') ?></td>
<td><?php include('main.php') ?></td>
</tr>
<tr>
<td colspan="2" >
<?php include('footer.php') ?>
</td>
</tr>
</table>
</body>
</html>

90. No
caching
TTL
10s
header.php
TTL
2s
menu.php main.php
footer.php
TTL
5s

91. <html>
<body>
<table>
<tr>
<td colspan="2" >
<esi:include src="/header.php" />
</td>
</tr>
<tr>
<td><esi:include src="/menu.php" /></td>
<td><esi:include src="/main.php" /></td>
</tr>
<tr>
<td colspan="2" >
<esi:include src="/footer.php" />
</td>
</tr>
</table>
</body>

92. <?php
function esi($file){
if(array_key_exists('HTTP_X_VARNISH',$_SERVER)){
header("esi-enabled: 1");
$url = 'http://'.$_SERVER['HTTP_HOST'].substr($_SERVER
['SCRIPT_NAME'],0,1+strrpos($_SERVER['SCRIPT_NAME'],'/')).
$file;
echo "<esi:include src="$url" />".PHP_EOL;
} else {
include($file);
}
}

93. <?php
class My_View_Helper_Esi extends Zend_View_Helper_Abstract
{
protected $_requestHeader;
protected $_responseHeader;
protected $_frontController;
public function esi
($controller = 'index', $action='index', $requestHeader = 'X_VARNISH',
$responseHeader = 'esi-enabled: 1')
{
$this->_requestHeader = $requestHeader;
$this->_responseHeader = $responseHeader;
$this->_frontController = Zend_Controller_Front::getInstance();
if($this->_getRequestHeader()){
$this->_getResponseHeader();
return $this->_buildEsi($controller,$action);
} else {
return $this->_dispatch($controller, $action);
}
}
...

94. ...
protected function _getRequestHeader()
{
if($this->_requestHeader === null || $this-
>_requestHeader === false){
return false;
}
$request = $this->_frontController->getRequest();
if($request->getHeader($this->_requestHeader) === false){
return false;
} else {
return true;
}
}
protected function _getResponseHeader()
{
if($this->_responseHeader !== null && $this-
>_responseHeader !== false){
header($this->_responseHeader);
}
}
...

95. ...
protected function _dispatch($controller,$action)
{
$request = new Zend_Controller_Request_Simple
($action, $controller);
$response = new Zend_Controller_Response_Http();
$dispatcher = $this->_frontController->getDispatcher();
$dispatcher->dispatch($request, $response);
return $response->getBody();
}
protected function _buildEsi($controller,$action)
{
$router = $this->_frontController->getRouter();
$url = $router->assemble(array('controller'=>
$controller,'action'=>$action));
return "<esi:include src="{$url}"/>";
}
}

96. <html>
<body>
<table>
<tr>
<td colspan="2" >
<?php echo $this->esi('index',‘header’) ?>
</td>
</tr>
<tr>
<td><?php echo $this->esi('index',‘menu’) ?></td>
<td><?php echo $this->esi('index',‘main’) ?></td>
</tr>
<tr>
<td colspan="2" >
<?php echo $this->esi('index',‘footer’) ?>
</td>
</tr>
</table>

97. sub vcl_recv {
if(req.url == "/header.php") {
return (pass);
}
if(req.url ~ "^/(footer|main|menu).php$") {
return (lookup);
}
}
sub vcl_fetch {
if (beresp.http.esi-enabled == "1") {
esi;
unset beresp.http.esi-enabled;
}
if(req.url == "/footer.php") {
set beresp.ttl = 5s;
}
if(req.url == "/menu.php") {
set beresp.ttl = 10s;
}
if(req.url == "/main.php") {
set beresp.ttl = 2s;
}
}

100. Q&A