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Inventory

To accommodate for smooth transition from lab deployment to subsequent automation activities, containerlab generates inventory files for different automation tools.

Ansible#

Ansible inventory is generated automatically for every lab. The inventory file can be found in the lab directory under the ansible-inventory.yml name.

Lab nodes are grouped under their kinds in the inventory so that the users can selectively choose the right group of nodes in the playbooks.

name: ansible
topology:
  nodes:
    r1:
      kind: crpd
      image: crpd:latest

    r2:
      kind: ceos
      image: ceos:latest

    r3:
      kind: ceos
      image: ceos:latest

    grafana:
      kind: linux
      image: grafana/grafana:7.4.3
all:
  children:
    crpd:
      hosts:
        clab-ansible-r1:
          ansible_host: <mgmt-ipv4-address>
    ceos:
      hosts:
        clab-ansible-r2:
          ansible_host: <mgmt-ipv4-address>
        clab-ansible-r3:
          ansible_host: <mgmt-ipv4-address>
    linux:
      hosts:
        clab-ansible-grafana:
          ansible_host: <mgmt-ipv4-address>

Removing ansible_host var#

If you want to use a plugin1 that doesn't play well with the ansible_host variable injected by containerlab in the inventory file, you can leverage the ansible-no-host-var label. The label can be set on per-node, kind, or default levels; if set, containerlab will not generate the ansible_host variable in the inventory for the nodes with that label.
Note that without the ansible_host variable, the connection plugin will use the inventory_hostname and resolve the name accordingly if network reachability is needed.

name: ansible
  topology:
    defaults:
      labels:
        ansible-no-host-var: "true"
    nodes:
      node1:
      node2:
all:
  children:
    linux:
      hosts:
        clab-ansible-node1:
        clab-ansible-node2:

User-defined groups#

Users can enforce custom grouping of nodes in the inventory by adding the ansible-inventory label to the node definition:

name: custom-groups
topology:
  nodes:
    node1:
      # <some node config data>
      labels:
        ansible-group: spine
    node2:
      # <some node config data>
      labels:
        ansible-group: extra_group

As a result of this configuration, the generated inventory will look like this:

  children:
    srl:
      hosts:
        clab-custom-groups-node1:
          ansible_host: 172.100.100.11
        clab-custom-groups-node2:
          ansible_host: 172.100.100.12
    extra_group:
      hosts:
        clab-custom-groups-node2:
          ansible_host: 172.100.100.12
    spine:
      hosts:
        clab-custom-groups-node1:
          ansible_host: 172.100.100.11

Topology Data#

Every time a user runs a deploy command, containerlab automatically exports information about the topology into topology-data.json file in the lab directory. Schema of exported data is determined based on a Go template specified in --export-template parameter, or a default template /etc/containerlab/templates/export/auto.tmpl, if the parameter is not provided.

Containerlab internal data that is submitted for export via the template, has the following structure:

type TopologyExport struct {
    Name        string                       `json:"name"`                  // Containerlab topology name
    Type        string                       `json:"type"`                  // Always 'clab'
    Clab        *CLab                        `json:"clab,omitempty"`        // Data parsed from a topology definitions yaml file
    NodeConfigs map[string]*types.NodeConfig `json:"nodeconfigs,omitempty"` // Definitions of nodes expanded with dynamically created data
}

To get the full list of fields available for export, you can export topology data with the following template --export-template /etc/containerlab/templates/export/full.tmpl. Note, some fields exported via full.tmpl might contain sensitive information like TLS private keys. To customize export data, it is recommended to start with a copy of auto.tmpl and change it according to your needs.

Example of exported data when using default auto.tmpl template:

name: srl02

topology:
  kinds:
    srl:
      type: ixr6
      image: ghcr.io/nokia/srlinux
  nodes:
    srl1:
      kind: srl
    srl2:
      kind: srl

  links:
    - endpoints: ["srl1:e1-1", "srl2:e1-1"]
{
  "name": "srl02",
  "type": "clab",
  "clab": {
    "config": {
      "prefix": "clab",
      "mgmt": {
        "network": "clab",
        "bridge": "br-<...>",
        "ipv4-subnet": "172.20.20.0/24",
        "ipv6-subnet": "2001:172:20:20::/64",
        "mtu": "1500",
        "external-access": true
      },
      "config-path": "<full path to a directory with srl02.clab.yml>"
    }
  },
  "nodes": {
    "srl1": {
      "index": "0",
      "shortname": "srl1",
      "longname": "clab-srl02-srl1",
      "fqdn": "srl1.srl02.io",
      "group": "",
      "labdir": "<full path to the lab node directory>",
      "kind": "srl",
      "image": "ghcr.io/nokia/srlinux",
      "mgmt-net": "",
      "mgmt-intf": "",
      "mgmt-ipv4-address": "172.20.20.3",
      "mgmt-ipv4-prefix-length": 24,
      "mgmt-ipv6-address": "2001:172:20:20::3",
      "mgmt-ipv6-prefix-length": 64,
      "mac-address": "",
      "labels": {
        "clab-mgmt-net-bridge": "br-<...>",
        "clab-node-group": "",
        "clab-node-kind": "srl",
        "clab-node-lab-dir": "<full path to the lab node directory>",
        "clab-node-name": "srl1",
        "clab-node-type": "ixr6",
        "clab-topo-file": "<full path to the srl02.clab.yml file>",
        "containerlab": "srl02"
      }
    },
    "srl2": {
      "index": "1",
      "shortname": "srl2",
      "longname": "clab-srl02-srl2",
      "fqdn": "srl2.srl02.io",
      "group": "",
      "labdir": "<full path to the lab node directory>",
      "kind": "srl",
      "image": "ghcr.io/nokia/srlinux",
      "mgmt-net": "",
      "mgmt-intf": "",
      "mgmt-ipv4-address": "172.20.20.2",
      "mgmt-ipv4-prefix-length": 24,
      "mgmt-ipv6-address": "2001:172:20:20::2",
      "mgmt-ipv6-prefix-length": 64,
      "mac-address": "",
      "labels": {
        "clab-mgmt-net-bridge": "br-<...>",
        "clab-node-group": "",
        "clab-node-kind": "srl",
        "clab-node-lab-dir": "<full path to the lab node directory>",
        "clab-node-name": "srl2",
        "clab-node-type": "ixr6",
        "clab-topo-file": "<full path to the srl02.clab.yml file>",
        "containerlab": "srl02"
      }
    }
  },
  "links": [
    {
      "a": {
        "node": "srl1",
        "interface": "e1-1",
        "mac": "<mac address>",
        "peer": "z"
      },
      "z": {
        "node": "srl2",
        "interface": "e1-1",
        "mac": "<mac address>",
        "peer": "a"
      }
    }
  ]
}

  1. For example Ansible Docker connection plugin. 



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