Network as Code: Automating BGP with Python and GoBGP

The Problem with "Conf t"

90% of network outages (like the recent Tier-1 route leak) are caused by human error. An engineer types router bgp 6500 instead of 65000, and suddenly traffic destined for YouTube is routed through a toaster in Nebraska.

We need to stop treating routers like pets and start treating them like cattle. Enter GoBGP.

What is GoBGP?

GoBGP is an open-source BGP implementation written in Go. Unlike Cisco/Juniper hardware, it is designed to be controlled via an API (gRPC). This allows us to write Python scripts that inject routes programmatically.

Practical Example: Safe Route Injection

Here is a Python script that connects to a GoBGP instance and advertises a prefix only if it passes validation checks.

import grpc
from api import gobgp_pb2, gobgp_pb2_grpc

def advertise_route(prefix, next_hop):
    # 1. Validation Logic
    if not validate_prefix_registry(prefix):
        raise ValueError(f"Prefix {prefix} is not owned by us!")

    # 2. Connect to Router
    channel = grpc.insecure_channel('localhost:50051')
    stub = gobgp_pb2_grpc.GobgpApiStub(channel)

    # 3. Construct Path
    nlri = gobgp_pb2.Family(afi=gobgp_pb2.AFI_IP, safi=gobgp_pb2.SAFI_UNICAST)
    # ... (Protobuf construction omitted for brevity)
    
    # 4. Push Route
    stub.AddPath(gobgp_pb2.AddPathRequest(path=path))
    print(f"Successfully advertised {prefix}")

CI/CD for Networking

Imagine a world where you update a YAML file in Git to change a route:

1. Engineer commits change to routes.yaml.
2. GitLab CI runs a simulation (using Batfish) to ensure no loops are created.
3. If tests pass, the Python script above pushes the config to the edge routers.

This is Network Reliability Engineering (NRE). It eliminates the "fat finger" problem and makes rollbacks instant.