Capstan tool downloads base unikernel and precompiled packages from publically available remote repository. By default, following S3 repository is used:
https://mikelangelo-capstan.s3.amazonaws.com
There is nothing special about repository, it's just a bunch of directories and files that are made available on the internet. No authentication is supported, just a simple HTTP/HTTPS download.
Repository is structured as follows:
mike
|- osv-loader #
| |- index.yaml # base unikernel (path is hard-coded in Capstan)
| |- osv-loader.qemu.gz #
packages
|- osv.bootstrap.mpm # actual package
|- osv.bootstrap.yaml # metadata describing package
|- erlang-7.0.mpm
|- erlang-7.0.yaml
|- ...
As shown above, there are two root directories in the repository: mike and packages.
This directory contains base unikernel that Capstan builds your own unikernel upon. The
"recipe" to prepare the two files is best shown here. To prepare the osv-loader.qemu.gz file we simply checkout
latest OSv master and build it. Then we take the
$OSV_DIR/build/last/loader.img file and tar.gz compress it into osv-loader.qemu.gz.
This direcotry contains all the Capstan packages. Each package is stored in two files that
only differ in suffix: {package-name}.mpm and {package-name}.yaml. The former is actually
a tar.gz file containting all the package files, but please make use of capstan package build
command to compress it, as can be seen in this "recipe". The latter is a simple metafile in yaml format.
It should be very simple to host your own Capstan repository, just make sure that you maintain the directory structure as described above.
Please consult this file to learn how to tell Capstan what remote repository to connect to.