ostree-ext

Extension APIs for ostree that are written in Rust, using the Rust ostree bindings.

module "tar": tar export/import

ostree's support for exporting to a tarball is lossy by default. This adds a new export format that is effectively a new custom repository mode combined with a hardlinked checkout.

This new export stream can be losslessly imported back into a different repository.

Filesystem layout

.
├── etc                # content is at traditional /etc, not /usr/etc
│   └── passwd
├── sysroot       
│   └── ostree         # ostree object store with hardlinks to destinations
│       ├── repo
│       │   └── objects
│       │       ├── 00
│       │       └── 8b
│       │           └── 7df143d91c716ecfa5fc1730022f6b421b05cedee8fd52b1fc65a96030ad52.file.xattrs
│       │           └── 7df143d91c716ecfa5fc1730022f6b421b05cedee8fd52b1fc65a96030ad52.file
│       └── xattrs    # A new directory with extended attributes, hardlinked with .xattr files
│           └── 58d523efd29244331392770befa2f8bd55b3ef594532d3b8dbf94b70dc72e674
└── usr
    ├── bin
    │   └── bash
    └── lib64
        └── libc.so

Think of this like a new ostree repository mode tar-stream or so, although right now it only holds a single commit.

A major distinction is the addition of special .xattr files; tar variants and support library differ too much for us to rely on this making it through round trips. And further, to support the webserver-in-container we need e.g. security.selinux to not be changed/overwritten by the container runtime.