Today I’m doing an assignment for my school’s linux servers class held by Tero Karvinen. The assignment is to install Varnish cache and edit the settings of it, to measure site speed with ‘ab’ (ApacheBench) included in ‘apache2-utils’ package and to analyze and speed up a site with Firebug.
I will do this assignment with my virtual private server I made in an earlier post running an installation of Ubuntu 14.04 LTS that has Apache already installed. Using a late 2013 MacBook Pro as the terminal running OS X 10.11.
Installing Varnish
To install Varnish, I needed to add their own repository to my apt sources. [1]
curl https://repo.varnish-cache.org/GPG-key.txt | sudo apt-key add -sudoedit /etc/apt/sources.list.d/varnish-cache.list
Pasted the following line to the new apt source file for varnish:
deb https://repo.varnish-cache.org/ubuntu/ trusty varnish-4.1
Then I could install the package:
sudo apt-get update sudo apt-get -y install varnish
Configuring Varnish and Apache
For varnish to work, I need it to be visible to the internet. This means I need Varnish to listen on port 80, while Apache is running back on another port discussing with Varnish. [2]
sudoedit /etc/default/varnish
Here I scrolled to the bottom of the file and changed the ‘DAEMON_OPTS’ setting so it listens on port 80.
DAEMON_OPTS="-a :80 \ -T localhost:6082 \ -f /etc/varnish/default.vcl \ -S /etc/varnish/secret \ -s malloc,256m"
Next up is Apache.
sudoedit /etc/apache2/ports.conf
I changed the first setting in file and changed it to listen on the port ‘8080’.
Listen 8080
Also, I need to change the VirtualHost configuration on the site.
sudoedit /etc/apache2/sites-available/metsanheimo.tk.conf
Right at the top, I changed the tag to also point to port ‘8080’.
<VirtualHost *:8080>
Now I needed to restart both daemons to read the new configuration.
sudo service apache2 restart sudo service varnish restart
Leveraging browser cache for media files using VCL configuration
One extra setting I added for varnish to improve speed and SEO ranking is browser caching.
sudoedit /etc/varnish/default.vcl
I searched the ‘vcl_backend_response’ function from the file and added this content. [3]
sub vcl_backend_response { if (bereq.url ~ "\.(png|gif|jpg|swf|css|js)$") { unset beresp.http.set-cookie; set beresp.http.cache-control = "max-age = 2592000"; } }
And of course restarting the daemon afterwards.
sudo service varnish restart
Measuring performance
I will measure the performance of my WordPress test site on the virtual server with ApacheBench. To use the tool, I need apache utils installed:
sudo apt-get install apache2-utils
Before
This test I made before the installation of Varnish, this command sends out 500×100 (100 requests at a time for 500 times) requests to the web server located at metsanheimo.tk.
ab -n 500 -c 100 http://metsanheimo.tk/ This is ApacheBench, Version 2.3 <$Revision: 1528965 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking metsanheimo.tk (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Apache/2.4.7 Server Hostname: metsanheimo.tk Server Port: 80 Document Path: / Document Length: 14746 bytes Concurrency Level: 100 Time taken for tests: 19.600 seconds Complete requests: 500 Failed requests: 0 Total transferred: 7499000 bytes HTML transferred: 7373000 bytes Requests per second: 25.51 [#/sec] (mean) Time per request: 3919.957 [ms] (mean) Time per request: 39.200 [ms] (mean, across all concurrent requests) Transfer rate: 373.64 [Kbytes/sec] received
Connection Times (ms) min mean[+/-sd] median max Connect: 1 10 77.1 1 998 Processing: 635 3798 1345.9 3661 6433 Waiting: 544 2671 1038.4 2259 4823 Total: 643 3808 1344.4 3678 6433
Percentage of the requests served within a certain time (ms) 50% 3678 66% 4203 75% 4516 80% 5145 90% 5879 95% 6047 98% 6229 99% 6336 100% 6433 (longest request)
Telling from the results above, the server took almost 20 seconds to respond to all the requests. Time per one request was almost 40ms.
After
ab -n 500 -c 100 http://metsanheimo.tk/ This is ApacheBench, Version 2.3 <$Revision: 1528965 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking metsanheimo.tk (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests
Server Software: Apache/2.4.7 Server Hostname: metsanheimo.tk Server Port: 80 Document Path: / Document Length: 14746 bytes Concurrency Level: 100 Time taken for tests: 0.768 seconds Complete requests: 500 Failed requests: 0 Total transferred: 7549104 bytes HTML transferred: 7373000 bytes Requests per second: 651.32 [#/sec] (mean) Time per request: 153.534 [ms] (mean) Time per request: 1.535 [ms] (mean, across all concurrent requests) Transfer rate: 9603.32 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 8 36 15.1 37 77 Processing: 32 82 37.2 72 371 Waiting: 32 76 21.4 72 138 Total: 72 118 33.6 110 412
Percentage of the requests served within a certain time (ms) 50% 110 66% 115 75% 123 80% 127 90% 138 95% 146 98% 268 99% 318 100% 412 (longest request)
With our glorious reverse proxy Varnish the response times crashed down. The first test took almost 20 seconds to complete, the test with Varnish took only 0,768 seconds and time per request was just 1.535ms compared to the 40ms before. Such grand results with just so simple installation.
After the VCL browser cache leverage
After the small vcl browser cache leverage setting the same command gave these results.
ab -n 500 -c 100 http://metsanheimo.tk/ This is ApacheBench, Version 2.3 <$Revision: 1528965 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking metsanheimo.tk (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Apache/2.4.7 Server Hostname: metsanheimo.tk Server Port: 80 Document Path: / Document Length: 14746 bytes Concurrency Level: 100 Time taken for tests: 0.629 seconds Complete requests: 500 Failed requests: 0 Total transferred: 7549138 bytes HTML transferred: 7373000 bytes Requests per second: 794.78 [#/sec] (mean) Time per request: 125.821 [ms] (mean) Time per request: 1.258 [ms] (mean, across all concurrent requests Transfer rate: 11718.56 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 8 36 14.0 37 77 Processing: 34 75 15.6 74 131 Waiting: 34 74 15.5 73 120 Total: 65 111 10.6 112 142 Percentage of the requests served within a certain time (ms) 50% 112 66% 115 75% 117 80% 118 90% 122 95% 127 98% 132 99% 135 100% 142 (longest request)
Again, we have a bit better results here. Time taken for the tests reduced by 0,139 seconds and time per request reduced by 0,277ms.
Examining site with Firebug
Here is a shot of what firebug shows about the caching of the site.
Firebug Net tab cache information
Here we can see that 843,5kb of the total page size of 848.4kb is coming from a cache. That is pretty a pretty good result. Only things that aren’t coming from the cache are two google fonts. They are also slowing down the load times a bit, because they need to be downloaded from another server. To fix this I could download the fonts locally.
Sources
Class by Tero Karvinen
[2][3] Configuring Varnish and Apache