Having Foreman + Katello, attempting to register a RHEL 7 host:

In host registration dialog, supply a hostgroup with associated activation key, generate the command.

Run the command on the host, fails with "Error: Must specify an activation key"

Verbose output excrept from the host:

```
echo "# Running registration"

1. Running registration
   echo "#" #

if [ x$ID = xrhel ] || [ x$ID = xcentos ]; then
register_katello_host(){
UUID=$(subscription-manager identity | head -1 | awk '{print $3}')
curl --cacert $SSL_CA_CERT --request POST "https://testhost.example.com/register?uuid=$UUID" \
-H 'Authorization: Bearer eyJhbGciOiJIUzI1NiJ9.eyJ1c2VyX2lkIjo0LCJpYXQiOjE2MDQ5MjcwODQsImp0aSI6ImJiMjE5MGE3NzdlZmMwMzM3OGQxZmY3YjEzNjZhN2U3MWIxNGI4NzE1OGZkNzYzZjkwNGVmNTY1ZDA3ZDE0YTciLCJleHAiOjE2MDQ5NDE0ODR9.O3MiKfD2RrDjE5sUsTJBuB2b718iSoxE6JDSeaPT4ag' \
--data "host[organization_id]=1" --data "host[location_id]=2"
}

CONSUMER_RPM=$(mktemp --suffix .rpm)
    curl --output $CONSUMER_RPM http://testhost.example.com/pub/katello-ca-consumer-latest.noarch.rpm
    yum localinstall $CONSUMER_RPM -y
    rm -f $CONSUMER_RPM

subscription-manager register --org=Default_Organization --activationkey="" 
    register_katello_host | bash
else
    register_host | bash
fi
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  8600  100  8600    0     0   133k      0 --:--:-- --:--:-- --:--:--  135k
Loaded plugins: product-id, search-disabled-repos, subscription-manager
This system is not registered with an entitlement server. You can use subscription-manager to register.
Examining /tmp/tmp.3kyMSSvKPs.rpm: katello-ca-consumer-testhost.example.com-1.0-1.noarch
/tmp/tmp.3kyMSSvKPs.rpm: does not update installed package.
Nothing to do
Error: Must specify an activation key
This system is not yet registered. Try 'subscription-manager register --help' for more information.
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   207    0   164  100    43    881    230 --:--:-- --:--:-- --:--:--   886
ERROR: not_found
Host was not found by the subscription UUID: '', this can happen if the host is registered already, but not to this Foreman
```

Seems like the AK is not supplied from the hostgroup to the template.

Btw. subscription-manager allows also registration without AK, with supplying just LC environment and content view, should that be supported in the template?