Several aspects of the Gateway's Debian package depend on `systemd`
being present. Without it, we don't have the necessary users and files
in place for the Gateway to function. With that specified, we can fail
the `postinst` script (and therefore the installation) if anything in
there goes wrong.
With this PR we add `cargo-deb` to our CI pipeline and build a debian
package for the Gateway. The debian package comes with several
configuration files that make it easy for admins to start and maintain a
Gateway installation:
- The embedded systemd unit file is essentially the same one as what we
currently install with the install script with some minor modifications.
- The token is read from `/etc/firezone/gateway-token` and passed as a
systemd credential. This allows us to set the permissions for this file
to `0400` and have it owned by `root:root`.
- The configuration is read from `/etc/firezone/gateway-env`.
- Both of these changes basically mean the user should never need to
touch the unit file itself.
- The `sysusers` configuration file ensures the `firezone` user and
group are present on the system.
- The `tmpfiles` configuration file ensures the necessary directories
are present.
All of the above is automatically installed and configured using the
post-installation script which is called by `apt` once the package is
installed.
In addition to the Gateway, we also package a first version of the
`firezone-cli`. Right now, `firezone-cli` (installed as `firezone`) has
three subcommands:
- `gateway authenticate`: Asks for the Gateway's token and installs it
at `/etc/firezone/gateway-token`. The user doesn't have to know how we
manage this token and can trust that we are using safe defaults.
- `gateway enable`: Enables and starts the systemd service.
- `gateway disable`: Disables the systemd service.
Right now, the `.deb` file is only uploaded to the preview APT
repository and not attached to the release. It should therefore not yet
be user-visible unless somebody pokes around a lot, meaning we can defer
documentation to a later PR and start testing it from the preview
repository for our own purposes.
Related: #10598Resolves: #8484Resolves: #10681
