By Tzach Livyatan

(Spoiler: It’s Apache Tomcat.)

Capstan is a tool for rapidly building and running applications on OSv. As with Docker, Capstan users can download and run images from a public repository. We chose to implement our public Capstan repository using Amazon S3.

Amazon S3 gives us the flexibility and security we need, but by default it’s missing a critical feature: download statistics. This statistics are very interesting to us, to evaluate which of the Capstan virtual appliances are more popular. Fortunately, there is an easy way to gather the stats we need.

After a short tools survey, we choose s3stat.

s3stat is a cloud-based service which can follow an S3 bucket, and visualize download statistics, by file, country, browser day, or otherwise. The price makes sense, and it is super easy to enable.

So what are the results? (drum roll….)

Omitting Capstan download of capstan index.yaml files, which Capstan does for every repository search, the most popular images are the base images for OSv and OSv + Java. That make sense because these two images will be used by anyone who wants to build a local OSv application, running a native or Java application.

Virtual appliances comes right after, with (drums again….) Tomcat, Cassandra, Memcached on the podium (Tomcat wins the Gold). These are all very early results, but we will keep using s3stat to follow Capstan image downloads.