How to do it...

1. Update the group_vars/all.yml file with the following BGP information:

bgp_topo:
  rr: mxp01
  af:
  - inet
  - inet-vpn

2. For each node within our Ansible inventory, we create a file called bgp.yml under the host_vars directory. This file holds the BGP information and BGP peers for each node. This is the example for the mxpe01 device:

$ cat host_vars/mxpe01/bgp.yml

bgp_asn: 65400

bgp_peers:
  - local_as: 65400
    peer: 10.100.1.254
    remote_as: 65400

3. Create a new Jinja2 file, bgp.j2, under the templates/junos directory, with the following data:

$ cat roles/build_router_config/templates/junos/bgp.j2
 
 protocols {
{%  if bgp_peers is defined %}
    bgp {
        group Core {
            type internal;
            local-address {{ lo_ip[inventory_hostname] | ipaddr('address')}};
{%          if bgp_topo.rr == inventory_hostname %}
            cluster {{ lo_ip[inventory_hostname].split('/')[0] }};
{%          endif %}
{%          for af in bgp_topo.af %}
{%          if af == 'inet' %}
            family inet {
                unicast;
            }
{%          endif %}
{%          if af == 'inet-vpn' %}
            family inet-vpn {
                unicast;
            }
{%          endif %}
<--   Output Trimmed for brevity ------>
{%          endfor %}
{%          for p in bgp_peers %}
            neighbor {{ p.peer}};
{%          endfor %}
        }
    }
{%  endif %}
}

4. In the build_device_config.yml file inside the tasks folder, add the following highlighted task:

$ cat roles/build_router_config/tasks/build_device_config.yml

<-- Output Trimmed for brevity ------>

- name: "BGP Configuration"
  template:
    src: "{{Ansible_network_os}}/bgp.j2"
    dest: "{{config_dir}}/{{ inventory_hostname }}/04_bgp.cfg"