* 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)). As of Ubuntu 18.04, `libostree-dev` is available in the main repositories, and the PPA is no longer required.
* [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 1.10.x or higher is required. If needed, golang kits are available at https://golang.org/dl/
This project is using [vndr](https://github.com/LK4D4/vndr) for managing dependencies, which is a tedious and error-prone task. Doing it manually is likely to cause inconsistencies between the `./vendor` directory (i.e., the downloaded dependencies), the source code that imports those dependencies and the `vendor.conf` configuration file that describes which packages in which version (e.g., a release or git commit) are a dependency.
To ease updating dependencies, we provide the `make vendor` target, which fetches all dependencies mentioned in `vendor.conf`. `make vendor` whitelists certain packages to prevent the `vndr` tool from removing packages that the test suite (see `./test`) imports.
The CI of this project makes sure that each pull request leaves a clean vendor state behind by first running the aforementioned `make vendor` followed by running `./hack/tree_status.sh` which checks if any file in the git tree has changed.
##### Vendor Troubleshooting
If the CI is complaining about a pull request leaving behind an unclean state, it is very likely right about it. Make sure to run `make vendor` and add all the changes to the commit. Also make sure that your local git tree does not include files not under version control that may reference other go packages. If some dependencies are removed but they should not, for instance, because the CI is needing them, then whitelist those dependencies in the `make vendor` target of the Makefile. Whitelisting a package will instruct `vndr` to not remove if during its cleanup phase.
#### 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: