title: How to use the security group existing in horizon in heat template
body: <p>I'm newbies on heat yaml template loaded by OpenStack 
  I've got this command which works fine : </p>
  
  <pre><code>openstack server create --image RHEL-7.4   --flavor std.cpu1ram1 --nic net-id=network-name.admin-network --security-group security-name.group-sec-default   value instance-name
  </code></pre>
  
  <p>I tried to write this heat file with the command above  :</p>
  
  <pre><code>heat_template_version: 2014-10-16
  
  description: Simple template to deploy a single compute instance with an attached volume
  
  resources:
    my_instance:
      type: OS::Nova::Server
      properties:
        name: instance-name
        image: RHEL-7.4
        flavor: std.cpu1ram1
        networks:
          - network: network-name.admin-network
        security_group: 
          - security_group: security-name.group-sec-default
  
  security-group: 
    type: OS::Neutron::SecurityGroup
  properties:
    rules: security-name.group-sec-default
  
    my_volume:
      type: OS::Cinder::Volume
      properties:
        size: 10
  
    my_attachment:
        type: OS::Cinder::VolumeAttachment
        properties:
          instance_uuid:  { get_resource: my_instance }
          volume_id: { get_resource: my_volume }
          mountpoint: /dev/vdb
  </code></pre>
  
  <p>The stack creation failed with the following message error : </p>
  
  <pre><code> openstack stack create -t my_first.yaml First_stack
   openstack stack show First_stack
  .../...
     | stack_status_reason   | Resource CREATE failed: BadRequest: resources.my_instance: Unable to find security_group with name or id 'sec_group1' (HTTP 400) (Request-ID: req-1c5d041c-2254-4e43-8785-c421319060d0) 
  .../...
  </code></pre>
  
  <p>Thanks for helping,</p>