[Phase 2] Build diff engine (current vs desired state) #7

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Damien · 2025-12-20T15:41:08Z

Damien commented

2025-12-20 15:41:08 +00:00

Description

Build the diff engine that compares current device state against desired state from NetBox.

Tasks

Normalize current state (from gNMI Get) into comparable format
Normalize desired state (from NetBox) into comparable format
Compute diff: what to CREATE, UPDATE, DELETE
Handle nested structures (VLANs within network-instance, etc.)
Generate human-readable diff output

Diff Types

class ChangeType(Enum):
    CREATE = "create"   # Exists in desired, not in current
    UPDATE = "update"   # Exists in both, values differ
    DELETE = "delete"   # Exists in current, not in desired
    NOOP = "noop"       # Identical

Example Output

Device: leaf1
  VLANs:
    + VLAN 40 (CREATE): name="test-l2-vxlan", vni=100040
    ~ VLAN 50 (UPDATE): name changed "old" -> "new"
    - VLAN 99 (DELETE): will be removed

Implementation Considerations

Deep comparison for nested YANG structures
Handle list ordering (YANG lists are often unordered)
Ignore operational state fields (only compare config)

Output

src/reconciler/diff.py

## Description Build the diff engine that compares current device state against desired state from NetBox. ## Tasks - [ ] Normalize current state (from gNMI Get) into comparable format - [ ] Normalize desired state (from NetBox) into comparable format - [ ] Compute diff: what to CREATE, UPDATE, DELETE - [ ] Handle nested structures (VLANs within network-instance, etc.) - [ ] Generate human-readable diff output ## Diff Types ```python class ChangeType(Enum): CREATE = "create" # Exists in desired, not in current UPDATE = "update" # Exists in both, values differ DELETE = "delete" # Exists in current, not in desired NOOP = "noop" # Identical ``` ## Example Output ``` Device: leaf1 VLANs: + VLAN 40 (CREATE): name="test-l2-vxlan", vni=100040 ~ VLAN 50 (UPDATE): name changed "old" -> "new" - VLAN 99 (DELETE): will be removed ``` ## Implementation Considerations - Deep comparison for nested YANG structures - Handle list ordering (YANG lists are often unordered) - Ignore operational state fields (only compare config) ## Output - `src/reconciler/diff.py`

Damien added the phase-2-minimal-reconciler label 2025-12-20 15:41:20 +00:00

Damien referenced this issue

2026-01-10 13:00:18 +00:00

[Phase 4] Create Kestra workflow for fabric reconciliation (plan/apply) #10

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Reference: Damien/fabric-orchestrator#7