Version-Specific Lab Topology Files¶
netlab offers two mechanisms you can use when working on projects that might be used in environments with unknown netlab versions:
Minimum netlab version required to run the lab topology.
Version-specific topology files
Minimum Netlab Version¶
You can specify minimum version required to run a lab topology in version attribute or in defaults.version attribute. The value of this attribute could be a simple version number (example:
1.6.4) or a Python version specifier (example:
For example, this is how you can ensure that netlab generates a useful error message when a user tries to run a lab topology that uses bgp.policy plugin (introduced in release 1.6.4):
module: [ bgp ] plugin: [ bgp.policy ] version: 1.6.4
The version attribute was introduced in netlab release 1.6.3. Prior netlab versions will report an invalid attribute.
Version-Specific Topology Files¶
Starting with netlab 1.6.4, netlab tries to find a topology file that is a best match for the installed netlab version.
When given a lab topology name (example:
topology.yml), netlab tries to find matching files that include a version number (example:
For example, when a directory contains
test.1.8.yml, netlab uses the following topology when you execute
netlab up test.yml
test.ymlfor releases prior to 1.6.4 (the version-specific topologies were introduced in 1.6.4)
test.1.6.3.ymlin releases starting from 1.6.4 and up to 1.8
test.1.8.ymlin releases starting from 1.8.0.
It’s highly recommended that you add version attribute to versioned topology files to ensure the user does not try to use a topology file not suitable for their netlab version
Using version-specific topology files can be confusing. To reduce the confusion, netlab prints a notice telling you which topology file it uses whenever it uses a version-specific topology file. You can also use the netlab inspect input command to display the topology file and all the default files netlab used to start the lab, for example:
$ netlab inspect input - /home/user/BGP/policy/6-med/topology.1.6.4.yml - /home/user/BGP/defaults.yml - /home/user/.netlab.yml - package:topology-defaults.yml