# Adding a Host to the Network

This document guides an admin through adding a single host to the network. Keep
in mind that the steps described here must be done for _each_ host the user
wishes to add.

There are two ways for a user to add a host to the isle network.

- If the user is savy enough to obtain their own `isle` binary, they can
  do so. The admin can then generate a `bootstrap.yml` file for their host,
  give that to the user, and the user can run `isle daemon` using that
  bootstrap file.

- If the user is not so savy, the admin can generate a custom `isle`
  binary with the `bootstrap.yml` embedded into it. The user can be given this
  binary and run `isle daemon` without any configuration on their end.

From the admin's perspective the only difference between these cases is one
extra step.

## Step 1: Choose Hostname

The user will need to provide you with a name for their host. The name should
conform to the following rules:

* It should only contain lowercase letters, numbers, and hyphens.

* It should begin with a letter.

* It should end with a letter or number.

## Step 2: Choose IP

The admin should choose an IP for the host. The IP you choose for the new host
should be one which is not yet used by any other host, and which is in subnet
which was configured when creating the network.

## Step 3: Create a `bootstrap.yml` File

Access to an `admin.yml` file is required for this step.

To create a `bootstrap.yml` file for the new host, the admin should perform the
following command from their own host:

```
isle admin create-bootstrap \
    --hostname <name> \
    --ip <ip> \
    --admin-path <path to admin.yml> \
    > bootstrap.yml
```

The resulting `bootstrap.yml` file should be treated as a secret file that is
shared only with the user it was generated for. The `bootstrap.yml` file should
not be re-used between hosts either.

If the user already has access to a `isle` binary then the new
`bootstrap.yml` file can be given to them as-is, and they can proceed with
running their host's `isle daemon`.

### Encrypted `admin.yml`

If `admin.yml` is kept in an encrypted format on disk (it should be!) then the
decrypted form can be piped into `create-bootstrap` over stdin. For example, if
GPG is being used to secure `admin.yml` then the following could be used to
generate a `bootstrap.yml`:

```
gpg -d <path to admin.yml.gpg> | isle admin create-bootstrap \
    --hostname <name> \
    --ip <ip> \
    --admin-path - \
    > bootstrap.yml
```

Note that the value of `--admin-path` is `-`, indicating that `admin.yml` should
be read from stdin.

## Step 4: Optionally, Build Binary

If you wish to embed the `bootstrap.yml` into a custom binary for the user (to
make installation _extremely_ easy for them) then you can run the following:

```
nix-build --arg bootstrap <path to bootstrap.yml> -A appImage
```

The resulting binary can be found in the `result` directory which is created.

This binary should be treated like a `bootstrap.yml` in terms of its uniqueness
and sensitivity.