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generate command#


The generate command generates the topology definition file based on the user input provided via CLI flags.

With this command it is possible to generate definition file for a CLOS fabric by just providing the number of nodes on each tier. The generated topology can be saved in a file or immediately scheduled for deployment.

It is assumed, that the interconnection between the tiers is done in a full-mesh fashion. Such as tier1 nodes are fully meshed with tier2, tier2 is meshed with tier3 and so on.


containerlab [global-flags] generate [local-flags]

aliases: gen



With the global --name | -n flag a user sets the name of the lab that will be generated.


The user configures the CLOS fabric topology by using the --nodes flag. The flag value is a comma separated list of CLOS tiers where each tier is defined by the number of nodes, its kind and type. Multiple --node flags can be specified.

For example, the following flag value will define a 2-tier CLOS fabric with tier1 (leafs) consists of 4x SR Linux containers of IXR-D3 type and the 2x Arista cEOS spines:


Note, that the default kind is srl, so you can omit the kind for SR Linux node. The same nodes value can be expressed like that: 4:ixrd3,2:ceos


With --kind flag it is possible to set the default kind that will be set for the nodes which do not have a kind specified in the --nodes flag.

For example the following value will generate a 3-tier CLOS fabric of cEOS nodes:

# cEOS fabric
containerlab gen -n 3tier --kind ceos --nodes 4,2,1

# since SR Linux kind is assumed by default
# SRL fabric command is even shorter
containerlab gen -n 3tier --nodes 4,2,1


Use --image flag to specify the container image that should be used by a given kind.

The value of this flag follows the kind=image pattern. For example, to set the container image ceos:4.21.F for the ceos kind the flag will be: --image ceos=ceos:4.21.F.

To set images for multiple kinds repeat the flag: --image srl=srlinux:latest --image ceos=ceos:4.21.F or use the comma separated form: --image srl=srlinux:latest,ceos=ceos:latest

If the kind information is not provided in the image flag, the kind value will be taken from the --kind flag.


With --license flag it is possible to set the license path that should be used by a given kind.

The value of this flag follows the kind=path pattern. For example, to set the license path for the srl kind: --license srl=/tmp/license.key.

To set license for multiple kinds repeat the flag: --license <kind1>=/path1 --image <kind2>=/path2 or use the comma separated form: --license <kind1>=/path1,<kind2>=/path2


When --deploy flag is present, the lab deployment process starts using the generated topology definition file.

The generated definition file is first saved by the path set with --file or, if file path is not set, by the default path of <lab-name>.clab.yml. Then the equivalent of the deploy -t <file> --reconfigure command is executed.


With --max-workers flag it is possible to limit the amout of concurrent workers that create containers or wire virtual links. By default the number of workers equals the number of nodes/links to create.

If during the deployment of a large scaled lab you see errors about max number of opened files reached, limit the max workers with this flag.


With --file flag its possible to save the generated topology definition in a file by a given path.


With --node-prefix flag a user sets the name prefix of every node in a lab.

Nodes will be named by the following template: <node-prefix>-<tier>-<node-number>. So a node named node1-3 means this is the third node in a first tier of a topology.

Default prefix: node.


With --group-prefix it is possible to change the Group value of a node. Group information is used in the topology graph rendering.


With --network flag a user sets the name of the management network that will be created by container orchestration system such as docker.

Default: clab.

ipv4-subnet | ipv6-subnet#

With --ipv4-subnet and ipv6-subnet its possible to change the address ranges of the management network. Nodes will receive IP addresses from these ranges if they are configured with DHCP.


Generate topology for a 3-tier CLOS network#

Generate and deploy a lab topology for 3-tier CLOS network with 8 leafs, 4 spines and 2 superspines. All using Nokia SR Linux nodes with license and image provided.


The srl kind in the image and license flags can be omitted, as it is implied by default

containerlab generate --name 3tier --image srl=srlinux:latest \
                      --license srl=license.key \
                      --nodes 8,4,2 --deploy