* A copy of the development libraries for `ostree`, either in the form of the `libostree-dev` package from the [flatpak](https://launchpad.net/~alexlarsson/+archive/ubuntu/flatpak) PPA, or built [from source](https://github.com/ostreedev/ostree) (more on that [here](https://ostree.readthedocs.io/en/latest/#building)).
* [runc Installation](https://github.com/containers/libpod/blob/master/docs/tutorials/podman_tutorial.md#installing-runc) - Although installable, the latest runc is not available in the Ubuntu repos. Version 1.0.0-rc4 is the minimal requirement.
If using an older release or a long-term support release, be careful to double-check that the version of `runc` is new enough (running `runc --version` should produce `spec: 1.0.0`), or else [build](https://github.com/containers/libpod/blob/master/docs/tutorials/podman_tutorial.md#installing-runc) your own.
Be careful to double-check that the version of golang is new enough, version 1.8.x or higher is required. If needed, golang kits are available at https://golang.org/dl/
#### Man Page: [registries.conf.5](https://github.com/containers/image/blob/master/docs/registries.conf.5.md)
`/etc/containers/registries.conf`
registries.conf is the configuration file which specifies which container registries should be consulted when completing image names which do not include a registry or domain portion.
#### Example from the Fedora `containers-common` package
```
cat /etc/containers/registries.conf
# This is a system-wide configuration file used to
# keep track of registries for various container backends.
# It adheres to TOML format and does not support recursive
# lists of registries.
# The default location for this configuration file is /etc/containers/registries.conf.
# The only valid categories are: 'registries.search', 'registries.insecure',
`/usr/share/containers/mounts.conf` and optionally `/etc/containers/mounts.conf`
The mounts.conf files specify volume mount directories that are automatically mounted inside containers when executing the `podman run` or `podman build` commands. Container process can then use this content. The volume mount content does not get committed to the final image.
Usually these directories are used for passing secrets or credentials required by the package software to access remote package repositories.
For example, a mounts.conf with the line "`/usr/share/rhel/secrets:/run/secrets`", the content of `/usr/share/rhel/secrets` directory is mounted on `/run/secrets` inside the container. This mountpoint allows Red Hat Enterprise Linux subscriptions from the host to be used within the container.
Note this is not a volume mount. The content of the volumes is copied into container storage, not bind mounted directly from the host.
#### Example from the Fedora `containers-common` package: