confgraph

Adding a New OS Parser

This guide walks through every file you need to touch to add full support for a new network OS. Follow the steps in order — each step depends on the previous ones.

---

Step 0: Choose a parser pattern

There are three patterns in this codebase. Pick the one that matches the config format:

Config format	Pattern	Example
IOS-style indented text	Extend IOSParser	EOS, NX-OS
Non-IOS indented text (brace/hierarchical)	Extend BaseParser, write custom tokenizer	JunOS
XML document	Extend BaseParser, use xml.etree.ElementTree	PAN-OS

If the syntax is close enough to IOS that 80%+ of parse_* methods work unchanged, extend IOSParser and only override the methods that differ (see EOSParser). Otherwise extend BaseParser directly.

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Step 1: Add the OS type

File: confgraph/models/base.py

Add a value to the OSType enum:

class OSType(str, Enum):
    ...
    MYOS = "myos"

---

Step 2: Create the parser class

File: confgraph/parsers/myos_parser.py

Extend BaseParser (or IOSParser). You must implement these four abstract methods at minimum — the rest have default stubs that return empty lists:

from confgraph.parsers.base import BaseParser
from confgraph.models.base import OSType

class MyOSParser(BaseParser):
    def __init__(self, config_text: str) -> None:
        super().__init__(config_text, OSType.MYOS, syntax="ios")

    def parse_vrfs(self) -> list[VRFConfig]: ...
    def parse_interfaces(self) -> list[InterfaceConfig]: ...
    def parse_bgp(self) -> list[BGPConfig]: ...
    def parse_ospf(self) -> list[OSPFConfig]: ...
    def parse_route_maps(self) -> list[RouteMapConfig]: ...
    def parse_prefix_lists(self) -> list[PrefixListConfig]: ...

All parse_* methods are wired into BaseParser.parse() automatically via _PARSE_STEPS. You do not need to call them yourself.

If using CiscoConfParse (IOS-style), call self._get_parse_obj() to get the lazy-loaded parse object.

If NOT using CiscoConfParse (XML, custom tokenizer), override:

• _extract_hostname() — return hostname from your format
• _collect_unrecognized_blocks() — return []

---

Step 3: Export from the parsers package

File: confgraph/parsers/__init__.py

from confgraph.parsers.myos_parser import MyOSParser

__all__ = [..., "MyOSParser"]

---

Step 4: Wire into the CLI

File: confgraph/cli.py

Two changes:

# 1. Add alias mapping
_OS_ALIAS = {..., "myos": "myos"}

# 2. Add detection heuristic
def _detect_os(text: str) -> OSType:
    for sig in ("MyOS-specific-string",):
        if sig in text:
            return OSType.MYOS
    ...

# 3. Add dispatch
if detected == OSType.MYOS:
    from confgraph.parsers.myos_parser import MyOSParser
    parsed = MyOSParser(text).parse()

# 4. Add to --os option choices
@click.option("--os", type=click.Choice([..., "myos"]))

---

Step 5: Add node styles to the graph builder

File: confgraph/graph/builder.py

If your OS introduces new node types (e.g., PAN-OS added zone), add entries to NODE_STYLE and NODE_LABEL_PREFIX, and add a node-creation block in _add_defined_nodes().

If your OS reuses existing node types (interfaces, bgp_instance, etc.), no changes needed here.

---

Step 6: Add dependency edges

File: confgraph/analysis/dependency_resolver.py

If your OS introduces new cross-reference relationships (e.g., zone → interface), add a _resolve_myos_thing() method and call it from resolve():

def resolve(self) -> DependencyReport:
    links = [...]
    links.extend(self._resolve_myos_thing())
    ...

def _resolve_myos_thing(self) -> list[DependencyLink]:
    links = []
    for zone in self._config.zones:
        for iface in zone.interfaces:
            links.append(self._link("zone", zone.name, "interface", "interface", iface))
    return links

---

Step 7: Update the HTML exporter (optional)

File: confgraph/graph/exporters/html.py

If your OS adds new node types that should appear as sidebar clusters, add an entry to CLUSTER_DEFS and to the LARGE_TYPES set and layout roots arrays:

const CLUSTER_DEFS = [
  ...
  { id: 'mytype', label: 'My Type', rootType: 'mytype', color: '#...' },
];

---

Step 8: Create a sample config

File: samples/myos_sample.<ext>

Create a realistic sample that exercises all implemented parse methods. Then generate its HTML:

uv run confgraph map samples/myos_sample.cfg --os myos --output-dir samples/

Verify with:

uv run confgraph info samples/myos_sample.cfg --os myos
uv run confgraph map  samples/myos_sample.cfg --os myos --lint

---

Step 9: Write documentation

Create docs/MYOS_PARSER_SUPPORT.md following the structure of any existing OS doc (e.g., PANOS_PARSER_SUPPORT.md):

• Key syntax differences from IOS
• One section per supported protocol — syntax example, differences, supported attributes, parsing status
• Implemented methods summary table
• Known limitations
• Validated confgraph info output
• Auto-detection signals

Then add a row to PARSER_SUPPORT_MATRIX.md and update README.md.

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Checklist

[ ] models/base.py          — OSType enum value
[ ] parsers/myos_parser.py  — Parser class implementing parse_* methods
[ ] parsers/__init__.py     — Export MyOSParser
[ ] cli.py                  — Alias, detection, dispatch, --os choice
[ ] graph/builder.py        — Node styles + _add_defined_nodes (if new node types)
[ ] analysis/dependency_resolver.py — New edge resolvers (if new relationships)
[ ] graph/exporters/html.py — CLUSTER_DEFS (if new sidebar clusters)
[ ] samples/               — Sample config + generated HTML
[ ] docs/MYOS_PARSER_SUPPORT.md
[ ] docs/PARSER_SUPPORT_MATRIX.md
[ ] README.md

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