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netlab Custom Groups and Deployment Templates

Using custom templates to test IP anycast with MPLS was fun, but as I got into interesting discussions focusing on convoluted details, I found myself going through the same set of steps too many times.

It started with the need to specify individual devices in netlab config command to create new loopback interfaces on anycast servers but not on any other device in the lab. Wouldn’t it be nice to have a group of devices (similar to Ansible groups) that one could use in the limit parameter of netlab config?

Original topology file
module: [ ospf ]
defaults.device: eos
provider: clab

nodes: [ l1, l2, l3, s1, a1, a2, a3 ]

links: [ s1-l1, s1-l2, s1-l3, l2-a1, l2-a2, l3-a3 ]

A few hours later1, I had them. netlab now support custom device groups.

netlab create or netlab up automatically create additional groups in Ansible inventory, and I can use the anycast group to execute netlab config ospf-anycast-loopback.j2 --limit anycast.

Topology file using groups
module: [ ospf ]
defaults.device: eos
provider: clab

groups:
  anycast:
    members: [ a1, a2, a3 ]

nodes: [ l1, l2, l3, s1, a1, a2, a3 ]

links: [ s1-l1, s1-l2, s1-l3, l2-a1, l2-a2, l3-a3 ]

Next: wouldn’t it be cool to deploy additional configuration templates during lab creation time? How about specifying them in the topology file? Like this…

module: [ ospf ]
defaults.device: eos
provider: clab

groups:
  anycast:
    members: [ a1, a2, a3 ]
    config: [ ospf-anycast-loopback.j2 ]
  all:
    config: [ mpls-ldp.j2 ]

nodes: [ l1, l2, l3, s1, a1, a2, a3 ]

links: [ s1-l1, s1-l2, s1-l3, l2-a1, l2-a2, l3-a3 ]

When netlab up is executed, the ospf-anycast-loopback.j2 configuration template should be deployed on anycast devices to create additional loopback interfaces, and mpls-ldp.j2 template should be deployed on all lab devices to enable MPLS forwarding and LDP.

Another hour or two and I got it up and running. Now I can execute netlab up and get a fully functional anycast-with-MPLS lab in one go.

Finally, as I was getting annoyed by the clutter generated by the Ansible playbooks, I implemented the quiet flag in netlab up command. It sets ANSIBLE_STDOUT_CALLBACK to selective which really quiets down ansible-playbook.


  1. Obviously it would be easier and faster to execute those commands by hand for the next five years, but this was more fun. ↩︎

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1 comments:

  1. I don't think you meant Javascript "netlab config ospf-anycast-loopback.js --limit anycast" but Jinja2 instead ;)

    Replies
    1. Thank you. Fixed... although it WOULD be fun deploying JavaScript on network devices, wouldn't it?

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