Help, advice, opinion needed about a new module for a switch

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1

Hi all,

I had posted to this list a month or so ago about writing a module for an HP switch (HP V1910-24G Switch, Comware 5.0-based).

This has been quite a learning experience!

I reviewed this with my team today and there were some concerns that I might’ve taken the wrong approach.

I’ll explain what I’m dealing with:

  1. This switch has an ssh interface and web UI (no exposed REST API that I can find)

  2. This switch has a limited command-set that you have to enable (a “developer command-line mode”) if you want to do any useful work. Enabling means you type in a command, answer ‘Y’ to confirm, then type in a password (http://h30499.www3.hp.com/t5/Web-and-Unmanaged/How-limited-is-the-1910-CLI/td-p/5966697#.VCTQ-ktZsnj)

  3. This switch has a very specific command set and levels of views within it

  4. This switch doesn’t offer the ability, that I can find, to be able to do anything such as get a python binary on it (the Arista switch guys seem to do this)

What I wrote:

  1. I originally looked at a connection plugin, but the connection isn’t the problem
  2. The problem I had using either the default ssh or paramiko, I originally though was the ssh part. It isn’t, it is that Ansible attempts to create a temporary directory on the host it is running against. The switch can’t do this before turning on the “developer command-line mode”.
  3. I needed up writing a module that uses paramiko, but from within the module itself, so this module has to use “local_action” and supply a hostname, username, and password in the playbook to connect.

My playbooks appear like:

file: switch.yml

  • hosts: localhost
    tasks:
  • name: set switch in developer mode
    local_action:
    module: hpswitch
    developer_mode: true
    host: 192.168.x.x
    save: true
    username: admin
    password: xxx
    timeout: 30
    vlans:
  • name: VLAN 11
    id: 11
    interfaces:
  • GigabitEthernet1/0/9
  • GigabitEthernet1/0/10
    state: present
  • name: VLAN 12
    id: 12
    interfaces:
  • GigabitEthernet1/0/11
  • GigabitEthernet1/0/12
    state: present

Which would create two VLANs. Or, I can use this form:

file: switch.yml

  • hosts: localhost
    tasks:
  • name: set switch in developer mode
    hpswitch: developer_mode=true host=192.168.x.x name=admin password=xxxx

It was pointed out to me the way Arista does it as something to look at:

  tasks:
         - name: create vlan 999
           action: arista_vlan vlan_id=999 logging=true

         - name: create / edit vlan 999
           action: arista_vlan vlan_id=999 name=test logging=true

         - name: remove vlan 999
           action: arista_vlan vlan_id=999 state=absent logging=true

This is very nice, but the Arista router has completely different features and it seems some sort of posix shell as well as python to use. I need to be very particular in how I talk to my switch.

The paramiko code I used I had to specifically use channel.send(cmd) and then read everything I could with channel.read() (as opposed to running exec_command()).

So, it seems to me that I need to somehow “hijack” the connection and have developer mode turned on before Ansible creates the temporary directory – and evan that (temp dir) I don’t know will work.

So, first off -

  1. What are the thoughts on the way I did this?
  2. Is there a way to use inventory hostname such that my playbook, even though using a local action, will use a connection to the remote machine without having it be in the playbook?
  3. Is having a remote temp dir required? Can it be turned off?
  4. Has anyone out there done anything like this?

Thank you!

PS. My fork is: https://github.com/CaptTofu/ansible, the features/hp_switch branch (work in progress!)

2

small correction: channel.recv(size)

3
  1. The problem I had using either the default ssh or paramiko, I originally though was the ssh part. It isn’t, it is that Ansible attempts to create a temporary directory on the host it is running against. The switch can’t do this before turning on the “developer command-line mode”.

Does ansible do this even with the raw module? http://docs.ansible.com/raw_module.html

Cheers,
Paul

4

Per some IRC discussion, I don’t recommend connections for anything that does not have a Linux shell and filesystem, they are a conduit only for “normal” ansible modules.

In many cases,networking gear uses it’s own API to the switch via local_action, and if an API is available over basic commands, that’s a good idea.

It may also have to use paramiko or a socket from the ansible module, but they shouldn’t be connections.

How the F5 load balancer modules or Arista networking modules work are different examples of how a module executes on the control machine and then references the device to talk to.