Implement default configuration deployment mode (sh/ns) for containers

[ipspace]

This change makes it the definition of Linux deployment scripts less error-prone as the 'clab' provider creates all the necessary node_config entries.

[ipspace]

@jbemmel -- what you asked for a while ago

[Copilot]

Pull request overview

This PR simplifies containerlab configuration by introducing a config_mode parameter that replaces explicit node_config dictionary entries. Instead of manually listing each module with its execution mode, devices can now specify a single config_mode value (e.g., 'sh' or 'ns'), and the clab provider automatically generates the necessary configuration entries.

Changes:

• Added add_default_config_mode() function to automatically populate _node_config based on the device's config_mode setting
• Replaced explicit node_config entries with config_mode: ns in linux.yml
• Replaced explicit node_config entries with config_mode: sh in bird.yml
• Updated documentation to explain the new config_mode parameter with examples

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
netsim/providers/clab.py	Implements add_default_config_mode() function and integrates it into the node transformation pipeline
netsim/devices/linux.yml	Simplifies configuration by using config_mode: ns instead of explicit node_config entries
netsim/daemons/bird.yml	Simplifies configuration by using config_mode: sh instead of explicit node_config entries
docs/dev/config/deploy.md	Documents the new config_mode parameter with usage examples and migration guidance

Comments suppressed due to low confidence (1)

netsim/providers/clab.py:1

• The 'ns' mode is not handled in the file_target assignment logic. Based on the old linux.yml configuration showing 'initial: :ns', the 'ns' mode should set file_target to an empty string (indicated by the colon with no path before it). However, the current code leaves file_target as an empty string for 'ns' mode implicitly rather than explicitly, which could be confusing. Consider adding an explicit elif clause for 'ns' mode or adding a comment explaining that empty file_target is intentional for 'ns' mode.

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[Copilot]

Extra space in 'clab.config_mode parameter**' - should be 'clab.config_mode** parameter'

Suggested change

	The **clab.config_mode parameter** can be used to replace these definitions with a simpler one:
	The **clab.config_mode** parameter can be used to replace these definitions with a simpler one: