LSWS Cache PURGE

LSWS Cache PURGE

Summary

As of 4.1.12, LSWS supports cache PURGE operation to accommodate the demand on cache manipulation.

Procedures

Here are the steps to PURGE cache:

Create a wrapper script purge.php for PURGE

<?php
$fp = fsockopen('192.168.0.81', 80, $errno, $errstr, 2);
if (!$fp) {
    echo "$errstr ($errno)\n";
} else {
    $out = "PURGE /hello.php HTTP/1.0\r\n"
    . "Host: www.example.com\r\n"
    //. "Authorization: Basic ".base64_encode("userid:password")."\r\n"
    . "Connection: Close\r\n\r\n";
    fwrite($fp, $out);
    echo $out;
    while (!feof($fp)) {
        echo fgets($fp, 128);
    }
    fclose($fp);
}
?>

Note:

We use internal IP address 192.168.0.80 for illustration purpose. In real world, make sure vhost listens on 192.168.0.80 for domain name www.example.com.
Authentication can be added to make the PURGE more secure. It is commented that out in the script to simplify the process.

Set up Rewrite Rules to Allow PURGE

put the following rules in .htaccess

RewriteEngine On
RewriteCond %{REQUEST_METHOD} ^HEAD|GET|PURGE$
RewriteCond %{REQUEST_URI} !^/purge\.php$
RewriteRule .* - [E=Cache-Control:max-age=120,L]

Note: PURGE needs to be in the allowed method.

Whitelist source IP to issue PURGE request

Admin Console ⇒ Configuration ⇒ Server ⇒ Security ⇒ Allow List

append Source_IP with tailing ‘T’ for trusted IP like ‘ALL, 192.168.0.81T’

Operations

1. Create Cache

1.1 point browser to http://www.example.com/hello.php

1.2 cache storage has a new file created for hello.php (for illustration, we clean cache storage in our lab prior to step 1).

[root@cptest diskcache]# ls -lrt */*/*
9/c/6:
total 12
-rw------- 1 nobody nobody 11638 May  2 15:42 9c6eae83978ecd87

[root@cptest diskcache]#

2. Request the same resource from cache

request http://www.example.com/hello.php again from browser. receive 'X-Litespeed-Cache: hit' response header as a prove

   Date: Wed, 02 May 2012 23:59:53 GMT
   Content-Encoding: gzip
   X-Litespeed-Cache: hit   <=== here it is
   Connection: Keep-Alive
   Content-Length: 10
   Server: LiteSpeed
   Vary: Accept-Encoding
   Content-Type: text/html
   Keep-Alive: timeout=5, max=100

3. Issue purge request from server

3.1 1st time, ‘200 Purged’ status returned.

   [test@test ~]$ php purge.php
   PURGE /hello.php HTTP/1.0
   Host: www.example.com
   Connection: Close

   HTTP/1.0 200 Purged
   Date: Wed, 02 May 2012 23:48:23 GMT
   Server: LiteSpeed
   Connection: close

   [test@test ~]$

Note: ‘HTTP/1.0 200 Purged’ indicates the resource is purged.

Rewrite Log shown

2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] strip base: '/' from URI: '/phpinfo.php'
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] Rule: Match 'phpinfo.php' with pattern '.*', result: 
1
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] Cond: Match 'PURGE' with pattern '^HEAD|GET|PURGE$', 
result: 1
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] Cond: Match '/phpinfo.php' with pattern '^/purge\.php
$', result: -1
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] apply cache-control: 'max-age=120'.
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] No substition
2012-05-02 15:43:20.280 [INFO] [192.168.0.81:60174-0#APVH_lstest.com] [REWRITE] Last Rule, stop!
2012-05-02 15:43:20.281 [NOTICE] [192.168.0.81:60174-0#APVH_lstest.com:cache] [PUBLIC CACHE] PURGE /phpinfo.php, result: 1
2012-05-02 15:43:20.281 [DEBUG] [192.168.0.81:60174-0#APVH_lstest.com:cache] HttpConnection::sendHttpError(),code=200 Purged

 ...

3.2 2nd purge request results in 405 error

   [test@test ~]$ php purge.php
   PURGE /hello.php HTTP/1.0
   Host: www.lstest.com
   Connection: Close

   HTTP/1.0 405 Method Not Allowed
   Date: Wed, 02 May 2012 23:37:44 GMT
   Server: LiteSpeed
   Connection: close
   Cache-Control: private, no-cache, max-age=0
   Pragma: no-cache
   Content-Type: text/html
   Content-Length: 383

   [test@test ~]$

Rewrite Log shown

2012-05-02 15:43:39.588 [NOTICE] [192.168.0.81:60175-0#APVH_lstest.com] Content len: 0, Request line: 'PURGE /phpinfo.php HTTP/1.1'
2012-05-02 15:43:39.588 [DEBUG] [192.168.0.81:60175-0#APVH_lstest.com] Find context with URI: [/], location: [/home/lstestc/public_html/]
...
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] strip base: '/' from URI: '/phpinfo.php'
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] Rule: Match 'phpinfo.php' with pattern '.*', result: 1
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] Cond: Match 'PURGE' with pattern '^HEAD|GET|PURGE$', result: 1
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] Cond: Match '/phpinfo.php' with pattern '^/purge\.php$', result: -1
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] apply cache-control: 'max-age=120'.
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] No substition
2012-05-02 15:43:39.588 [INFO] [192.168.0.81:60175-0#APVH_lstest.com] [REWRITE] Last Rule, stop!
2012-05-02 15:43:39.588 [DEBUG] [192.168.0.81:60175-0#APVH_lstest.com] HttpConnection::sendHttpError(),code=405 Method Not Allowed
2012-05-02 15:43:39.588 [DEBUG] [192.168.0.81:60175-0#APVH_lstest.com] redirect to: 
        URI=[/405.shtml],
        QueryString=[]

4. Verify cache is purged

4.1 check cache file – gone

   [test@test ~]$ ls -lrt */*/*

   9/c/6:
   total 0
   [test@test ~]$

4.2 request resource 3rd time from browser, *no* ‘X-Litespeed-Cache: hit’ response header received.

   Date: Wed, 02 May 2012 23:42:18 GMT
   Content-Encoding: gzip
   Transfer-Encoding: Identity
   Connection: close
   Server: LiteSpeed
   Vary: Accept-Encoding
   Content-Type: text/html

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