From 41ffd07f3eb4a357405dd69c97f85e3db24a6fc2 Mon Sep 17 00:00:00 2001
From: Dmitry Kovba <dkovba@apple.com>
Date: Thu, 23 Apr 2026 08:05:25 -0700
Subject: [PATCH] Add a default route to the first interface only (#697)

Adds a default route to the first interface only.
---
 Sources/Containerization/LinuxContainer.swift | 7 ++++++-
 Sources/Containerization/LinuxPod.swift       | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/Sources/Containerization/LinuxContainer.swift b/Sources/Containerization/LinuxContainer.swift
index ab8c0fb..24924cb 100644
--- a/Sources/Containerization/LinuxContainer.swift
+++ b/Sources/Containerization/LinuxContainer.swift
@@ -590,12 +590,16 @@ extension LinuxContainer {
                     // For every interface asked for:
                     // 1. Add the address requested
                     // 2. Online the adapter
-                    // 3. If a gateway IP address is present, add the default route.
+                    // 3. For the first interface, add the default route
+                    var defaultRouteSet = false
                     for (index, i) in self.interfaces.enumerated() {
                         let name = "eth\(index)"
                         self.logger?.debug("setting up interface \(name) with address \(i.ipv4Address)")
                         try await agent.addressAdd(name: name, ipv4Address: i.ipv4Address)
                         try await agent.up(name: name, mtu: i.mtu)
+                        if defaultRouteSet {
+                            continue
+                        }
                         if let ipv4Gateway = i.ipv4Gateway {
                             if !i.ipv4Address.contains(ipv4Gateway) {
                                 self.logger?.debug("gateway \(ipv4Gateway) is outside subnet \(i.ipv4Address), adding a route first")
@@ -606,6 +610,7 @@ extension LinuxContainer {
                             self.logger?.debug("no gateway for \(name)")
                             try await agent.routeAddDefault(name: name, ipv4Gateway: nil)
                         }
+                        defaultRouteSet = true
                     }
 
                     // Setup /etc/resolv.conf and /etc/hosts if asked for.
diff --git a/Sources/Containerization/LinuxPod.swift b/Sources/Containerization/LinuxPod.swift
index a37ce06..035e1a8 100644
--- a/Sources/Containerization/LinuxPod.swift
+++ b/Sources/Containerization/LinuxPod.swift
@@ -444,12 +444,16 @@ extension LinuxPod {
                     // For every interface asked for:
                     // 1. Add the address requested
                     // 2. Online the adapter
-                    // 3. If a gateway IP address is present, add the default route.
+                    // 3. For the first interface, add the default route
+                    var defaultRouteSet = false
                     for (index, i) in self.interfaces.enumerated() {
                         let name = "eth\(index)"
                         self.logger?.debug("setting up interface \(name) with address \(i.ipv4Address)")
                         try await agent.addressAdd(name: name, ipv4Address: i.ipv4Address)
                         try await agent.up(name: name, mtu: i.mtu)
+                        if defaultRouteSet {
+                            continue
+                        }
                         if let ipv4Gateway = i.ipv4Gateway {
                             if !i.ipv4Address.contains(ipv4Gateway) {
                                 self.logger?.debug("gateway \(ipv4Gateway) is outside subnet \(i.ipv4Address), adding a route first")
@@ -460,6 +464,7 @@ extension LinuxPod {
                             self.logger?.debug("no gateway for \(name)")
                             try await agent.routeAddDefault(name: name, ipv4Gateway: nil)
                         }
+                        defaultRouteSet = true
                     }
 
                     // Setup /etc/resolv.conf and /etc/hosts for each container.