Deploying Custom Device Configurations

netlab config uses an internal Ansible playbook (netsim/ansible/config.ansible) to deploy custom device configurations generated from the supplied Jinja2 template(s) to lab devices.


netlab config command does not need a topology file (so you don’t have to specify one even if you’re using a non-default topology name). It’s just a thin wrapper around an Ansible playbook that uses Ansible inventory created by the netlab create or netlab up command.


usage: netlab config [-h] [-r] [-v] [-q] template

Deploy custom configuration template

positional arguments:
  template       Configuration template or a directory with templates

  -h, --help     show this help message and exit
  -r, --reload   Reload saved device configurations
  -v, --verbose  Verbose logging (add multiple flags for increased verbosity)
  -q, --quiet    Report only major errors

All other arguments are passed directly to ansible-playbook

Selecting Configuration Template

When the configuration template specified in the netlab config command is not a Jinja2 template, the command tries to find the configuration template for individual lab devices using node name, netlab_device_type, and ansible_network_os Ansible variables, allowing you to create a set of templates to deploy the same functionality to lab devices running different network operating systems.

See Custom Deployment Templates and Finding Custom Configuration Templates for more details.

Limiting the Scope of Configuration Deployments

All unrecognized parameters are passed to the internal config.ansible Ansible playbook. You can use ansible-playbook CLI parameters to modify the configuration deployment, for example:

  • -l parameter to deploy device configurations on a subset of devices.

  • -C parameter to run the Ansible playbook in dry-run mode.

Restoring Saved Device Configurations

netlab config –reload implements the reload saved device configurations part of the netlab initial -r command. It waits for devices to become ready (because it’s used immediately after a lab has been started) and starts the initial configuration process on devices that need more than a replay of saved configuration (more details).

After that, it treats the saved device configurations as custom templates and uses the same process as the regular netlab config command.

Debugging Device Configurations

To display device configurations within the Ansible playbook without deploying them, use -v --tags test parameters after the template name.

The -v flag will trigger a debugging printout, and the bogus test flag will skip the actual configuration deployment.