Inspect Data Structures in Transformed Lab Topology

netlab inspect prints data structures in a transformed lab topology (more details). You can display data in YAML or JSON format and select a subset of data from the transformed topology or an individual node.

When selecting data from an individual node, netlab adds group variables to node data, effectively displaying what you would see in the Ansible inventory.

Note

The netlab inspect command is replicating the functionality of the netlab create -o yaml:expression command with a more convenient user interface.

Usage

usage: netlab inspect [-h] [--node NODE] [--all] [--format {yaml,json}] [-q]
                      [-i INSTANCE] [--snapshot [SNAPSHOT]] [-t TOPOLOGY]
                      [expr]

Inspect data structures in a lab topology

positional arguments:
  expr                  Data selection expression

options:
  -h, --help            show this help message and exit
  --node NODE           Display data for selected node(s)
  --all                 Add global Ansible variables to node data
  --format {yaml,json}  Select data presentation format
  -q, --quiet           Report only major errors
  -i, --instance INSTANCE
                        Specify lab instance to inspect
  --snapshot [SNAPSHOT]
                        Transformed topology snapshot file
  -t, --topology TOPOLOGY
                        Topology file or URL

The netlab inspect command gets its data from:

The topology file specified with the -t argument
The lab instance specified with the -i argument
The snapshot file specified with the --snapshot argument
The default snapshot file (netlab.snapshot.pickle)
The default lab topology file (topology.yml)

The netlab.snapshot.pickle snapshot file is created when a lab is started and deleted when you shut down the lab with the netlab down --cleanup command.

Topology Inspection Examples

To display this information…	…use this command
whole transformed topology	`netlab inspect`
node data	`netlab inspect nodes`
address pools	`netlab inspect addressing`

You can inspect any subset of the lab topology, for example:

To display this information…	…use this command
device data for device `eos`	`netlab inspect defaults.devices.eos`
valid attributes for the BGP module	`netlab inspect defaults.bgp.attributes`

Finally, the data selection argument is evaluated as a Python expression, so you can display most things that can be expressed as a one-line expression (don’t forget to quote the expression):

To display this information…	…use this command
node names	`netlab inspect 'list(nodes.keys())'`

Node Inspection Examples

You can use the --node parameter to inspect the data structure of a single node, a group of nodes (where all is equivalent to *), all nodes running the specified device type, or all nodes matching a wildcard (glob) expression. You can also specify multiple parameters separated by commas.

To display this information…	…use this command
data for node `r1`	`netlab inspect --node r1`
interface data for node `r1`	`netlab inspect --node r1 interfaces`
first interface on node `r1`	`netlab inspect --node r1 'interfaces[0]'`
BGP parameters on R1 and R2	`netlab inspect --node r1,r2 bgp`
BGP parameters of routers in group as65101	`netlab inspect --node as65101 bgp`
BGP parameters of FRR devices	`netlab inspect --node frr bgp`
BGP parameters of IOL and EOS devices	`netlab inspect --node iol,eos bgp`
VRFs on all nodes	`netlab inspect --node '*' vrfs`
VRFs on all nodes (alternate)	`netlab inspect --node all vrfs`
VLANs on all nodes start with ‘r’	`netlab inspect --node 'r*' vlans`

Warning

You can use Python expressions only when specifying a single node to inspect.

Node data includes Ansible group variables, for example:

$ netlab inspect --node r1
af:
  ipv4: true
ansible_connection: network_cli
ansible_host: 192.168.121.101
ansible_network_os: eos
ansible_ssh_pass: vagrant
ansible_user: vagrant
box: arista/veos
...

Tip

Use the --all option if you want to display the global variables available in Ansible playbooks (address pools, paths, named prefixes)

Data from multiple nodes is shown in a tabular format, for example:

$ netlab inspect --node r1,r2 loopback
┏━━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ r1                      ┃ r2                      ┃
┡━━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ ifindex: 0              │ ifindex: 0              │
│ ifname: Loopback0       │ ifname: Loopback0       │
│ ipv4: 10.0.0.1/32       │ ipv4: 10.0.0.2/32       │
│ neighbors: []           │ neighbors: []           │
│ type: loopback          │ type: loopback          │
│ virtual_interface: true │ virtual_interface: true │
└─────────────────────────┴─────────────────────────┘