In order to get the best out of Docker, it’s important to measure and collect some metrics and identify areas that are bottlenecks and can be improved.
Docker Filesystem performance
This article discusses the different storage mechanisms and how they affect creating Docker containers en masse. Some of the newer options are considerably quicker and should be used if they are available. Avoid AUFS.
Benchmarking IO performance
docker run -it antonyh/cucumber dd if=/dev/zero \ of=outfile bs=1M count=2000 oflag=direct \ && iostat|grep sdc
This tests the disk IO performance of the docker server.
Run an Apache Benchmark using Docker
Apache Bench, sometimes known as ‘ab’ after the command used to invoke it, is a tool to measure the time taken to serve a single page at a given level of concurrency. As it’s part of Apache HTTPd, it’s very easy to run a test using Docker:
docker run --rm httpd ab http://126.96.36.199:1234/path/to/page
If the image had the ‘man command (it doesn’t), you could have viewed the ‘ab’ manual via docker, but sadly this doesn’t work.
docker run --rm httpd man ab
The next best bet to get instructions if you need them is the internet, directly from Apache: http://httpd.apache.org/docs/2.4/programs/ab.html although be aware this might be a different version to the docker image.