Add Nokia SRL (Service Router Linux) Platform Driver

[jtdub]

Overview

Add a new platform driver for Nokia SRL (Service Router Linux) to enable hier_config to parse SRL configurations and generate accurate remediation commands. This is needed to support Nokia SR Linux devices in nautobot-app-golden-config.

Background

Nokia SR Linux uses a hierarchical CLI with indentation-based config blocks. SRL uses delete for negation (similar to VyOS's delete/set pattern), and has platform-specific sectional constructs for features like:

• network-instance (VRF-equivalent blocks)
• interface sub-configurations
• routing-policy / route-table blocks
• system config blocks

Required Changes

1. Add Platform Enum Entry

File: hier_config/models.py

Add NOKIA_SRL = auto() to the Platform enum.

2. Create Driver Module

New files:

hier_config/platforms/nokia_srl/
├── __init__.py
└── driver.py

driver.py must subclass HConfigDriverBase and implement _instantiate_rules() returning an HConfigDriverRules instance with Nokia SRL-specific rules. At minimum, investigate and configure:

• negation_prefix / declaration_prefix (SRL uses delete for removal)
• sectional_exiting rules (e.g., exit or quit within config blocks)
• idempotent_commands (e.g., IP address assignments within interfaces)
• per_line_sub (e.g., strip timestamps or auto-generated comments from info detail output)
• config_preprocessor() if SRL's hierarchical flat-format (info flat) needs normalization

3. Register Driver

File: hier_config/constructors.py

Import HConfigDriverNokiaSRL and add it to the platform_drivers dict in get_hconfig_driver().

4. Write Tests

New file: tests/test_driver_nokia_srl.py

Follow patterns from tests/test_driver_vyos.py and tests/test_driver_arista_eos.py. Cover:

• Basic remediation (add/remove/change config lines)
• Interface configuration remediation
• network-instance (VRF) block handling
• Sectional exiting behavior
• Negation behavior

5. Update Changelog

Add entry under ## [Unreleased] in CHANGELOG.md:

### Added
- Nokia SRL platform driver (`Platform.NOKIA_SRL`) (#<this issue number>)

Related Work

After this driver is merged, a follow-up PR to netutils will be needed with the following changes:

netutils: Add to hier_config lib mapper

• netutils/lib_mapper.py lines 420-430 — add "nokia_srl" to the hier_config platform list
• netutils/lib_mapper.py lines 595-605 — add the reverse mapping entry

netutils: Add to HCONFIG_PLATFORM_V2_TO_V3_MAPPING

Nokia SRL did not exist in hier_config v2, so there is no v2 equivalent to map from. However, the HCONFIG_PLATFORM_V2_TO_V3_MAPPING dict in netutils still requires a "nokia_srl" entry pointing to Platform.NOKIA_SRL so that the mapper remains complete for v3 consumers.

Nokia SRL CLI Reference

Key behaviors to validate during implementation:

• SRL config display format: info (hierarchical) vs info flat (flat/set-style)
• Negation syntax: delete prefix on leaf nodes
• Indentation: typically 4 spaces per level
• Config blocks end with exit or are implicitly closed by indentation

Acceptance Criteria

• Platform.NOKIA_SRL enum value exists
• HConfigDriverNokiaSRL driver implemented with appropriate rules
• Driver registered in get_hconfig_driver()
• Test file covers basic and platform-specific scenarios
• Full lint + test suite passes (poetry run ./scripts/build.py lint-and-test)
• 95% test coverage maintained
• CHANGELOG.md updated