ab, Apache Bench, is often used to load test websites, but I didn’t find it extensible enough for my needs.
Unless an unofficial patch is applied, ab cannot simulate a real person by going to random URLs over a specified period of time. This is where siege comes in.
Install siege
siege should be available in most popular package management systems and is an apt-get install, yum install, or brew install away.
Once siege is installed, get familiar with its features by running siege --help or by reading the man page.
Load Testing Your Website
Gather all the URLs an enduser might go to on your website and put those URLs into a text file.
For example, create a file called urls.txt with the following content:
http://example.com/this-is-example-one.html
http://example.com/this-is-example-two.html
http://example.com/this-is-example-three.html
http://example.com/this-is-example-four.html
http://example.com/this-is-example-five.html
http://example.com/this-is-example-six.html
With the text file created containing all your URLs, it’s time to run siege.
The following command will create 50 concurrent connections (scale up the concurrent connections if needed), the --internet command line switch will attempt to simulate a real person for each of those connections by randomly going to URLs in the text file you created above, and the text file is specified with the --file command line switch.
siege --concurrent=50 --internet --file urls.txt
You can stop the command at any time and it will output a report. Alternatively, specify a time to run the test with the --time command line switch.
Load Testing Your API
siege can also be used to load test your API.
Instead of gathering a bunch of URLs and having siege randomly access them, you will likely be hitting a single URL endpoint and POSTing data to it.
The following command will create 50 concurrent connections and POST plain text data - plain-text-content-here - to the URL specified:
siege --concurrent=50 --content-type="text/plain" 'http://example.com/api POST plain-text-content-here'
If your API accepts JSON instead of plain text, use the following command instead:
siege --concurrent=50 --content-type="application/json" 'http://example.com/api POST {"key1":"value1","key2":"value2"}'
Additionally, you can POST JSON data from a file:
siege --concurrent=50 --content-type="application/json" 'http://example.com/api POST < /path/to/json-file.txt'
Once again, you can stop the command at any time and it will output a report. Alternatively, specify a time to run the test with the --time command line switch.
