smoke: simplify bgp test

[rjarry]

The previous test architecture was overly complex with two separate network namespaces simulating end hosts connected through routers. This complexity made the test harder to understand and maintain while not providing additional validation of BGP functionality.

Simplify the test to focus on the core requirement: verify that grout can learn BGP routes from an FRR peer and use them for forwarding. The test now uses an iBGP session between grout and a single FRR instance running in a network namespace. The FRR peer advertises a route to its loopback interface which grout must learn and use to successfully ping the remote address.

This reduces the number of interfaces from three to one and eliminates the need for two additional network namespaces and veth pairs.

Summary by CodeRabbit

• Tests
  • Streamlined BGP routing test: replaced multi-host topology with a single contained BGP peer namespace, moved interface and route setup into that namespace, and removed prior preconfigured host/loopback routing.
  • Simplified readiness and validation: replaced multi-step route-learning checks with a repeated route-presence loop and switched end-to-end validation to an in-namespace ping, improving reliability and speed.

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

The test replaces host-based BGP checks with an isolated FRR+Grout peer in the bgp-peer namespace. FRR is configured via vtysh with router-id 172.16.0.2, neighbor 172.16.0.1 remote-as 64512, and advertises 172.16.0.0/24 and 16.0.0.0/24. Interface x-p0 is assigned 172.16.0.2/24 and FRR loopback 16.0.0.1/24. Grout loopback preconfiguration and host routing are removed. Readiness uses a retry loop checking Grout for the learned 16.0.0.0/24 route (40 attempts, 0.5s sleep). Validation uses Grout grcli ping to 16.0.0.1.

Pre-merge checks

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'smoke: simplify bgp test' directly and clearly summarizes the main change—simplifying the BGP smoke test from a complex multi-namespace setup to a streamlined single-namespace FRR peer configuration.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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Reviewing files that changed from the base of the PR and between 15acc17 and 115a792.

📒 Files selected for processing (1)

• smoke/bgp_frr_test.sh (1 hunks)

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[maxime-leroy]

For vpn srv6 with bgp, it could be useful to have 2 netns to simulate 2 hosts.