From a637ba532cb3be102e1678abc2937a46f1b5ba10 Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <5619885+DilumAluthge@users.noreply.github.com>
Date: Sat, 24 Oct 2026 00:56:33 -0400
Subject: [PATCH 1/2] Worker: Bind to the first non-link-local IPv4 address

This is a cherry-pick of https://github.com/JuliaLang/Distributed.jl/pull/137

(cherry picked from commit 3679026d7b510befdedfa8c6497e3cb032f9cea1)
---
 src/cluster.jl | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/src/cluster.jl b/src/cluster.jl
index 0e85bbb..12563ac 100644
--- a/src/cluster.jl
+++ b/src/cluster.jl
@@ -1656,6 +1656,28 @@ function terminate_all_workers()
     end
 end
 
+function choose_bind_addr()
+    # We prefer IPv4 over IPv6.
+    #
+    # We also prefer non-link-local over link-local.
+    # (This is because on HPC clusters, link-local addresses are usually not
+    # usable for communication between compute nodes.
+    #
+    # Therefore, our order of preference is:
+    # 1. Non-link-local IPv4
+    # 2. Non-link-local IPv6
+    # 3. Link-local IPv4
+    # 4. Link-local IPv6
+    addrs = getipaddrs()
+    i = something(
+        findfirst(ip -> !islinklocaladdr(ip) && ip isa IPv4, addrs), # first non-link-local IPv4
+        findfirst(ip -> !islinklocaladdr(ip) && ip isa IPv6, addrs), # first non-link-local IPv6
+        findfirst(ip -> ip isa IPv4, addrs), # first IPv4
+        findfirst(ip -> ip isa IPv6, addrs), # first IPv6
+    )
+    return addrs[i]
+end
+
 # initialize the local proc network address / port
 function init_bind_addr()
     opts = JLOptions()
@@ -1677,15 +1699,12 @@ function init_bind_addr()
             end
         end
     else
-        interfaces = _get_interfaces(IPv4)
-        if isempty(interfaces)
-            # Include IPv6 interfaces if there are no IPv4 ones
-            interfaces = _get_interfaces()
-        end
-
-        if isempty(interfaces)
-            # All networking is unavailable, initialize bind_addr to the loopback address.
-            # An exception will be raised later if even that is unavailable.
+        bind_port = 0
+        try
+            bind_addr = string(choose_bind_addr())
+        catch
+            # All networking is unavailable, initialize bind_addr to the loopback address
+            # Will cause an exception to be raised only when used.
             bind_addr = "127.0.0.1"
         else
             # Pick the interface with the highest negotiated speed, if any

From 482d74b00f82f4c994a2671d8ed4efb6667b950d Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <5619885+DilumAluthge@users.noreply.github.com>
Date: Sat, 24 Oct 2026 01:06:25 -0400
Subject: [PATCH 2/2] Re-do the conflict resolution, but this time stay more
 faithful to the way DistributedNext does things

---
 src/cluster.jl | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/src/cluster.jl b/src/cluster.jl
index 12563ac..7cde178 100644
--- a/src/cluster.jl
+++ b/src/cluster.jl
@@ -1656,7 +1656,7 @@ function terminate_all_workers()
     end
 end
 
-function choose_bind_addr()
+function possible_bind_interfaces()
     # We prefer IPv4 over IPv6.
     #
     # We also prefer non-link-local over link-local.
@@ -1668,14 +1668,24 @@ function choose_bind_addr()
     # 2. Non-link-local IPv6
     # 3. Link-local IPv4
     # 4. Link-local IPv6
-    addrs = getipaddrs()
-    i = something(
-        findfirst(ip -> !islinklocaladdr(ip) && ip isa IPv4, addrs), # first non-link-local IPv4
-        findfirst(ip -> !islinklocaladdr(ip) && ip isa IPv6, addrs), # first non-link-local IPv6
-        findfirst(ip -> ip isa IPv4, addrs), # first IPv4
-        findfirst(ip -> ip isa IPv6, addrs), # first IPv6
-    )
-    return addrs[i]
+    interfaces = _get_interfaces()
+    ipv4_nonlinklocal = filter(i -> !islinklocaladdr(i.ip) && i.ip isa IPv4, interfaces) # non-link-local IPv4
+    ipv6_nonlinklocal = filter(i -> !islinklocaladdr(i.ip) && i.ip isa IPv6, interfaces) # non-link-local IPv6
+    ipv4 = filter(i -> i.ip isa IPv4, interfaces) # IPv4
+    ipv6 = filter(i -> i.ip isa IPv6, interfaces) # IPv6
+    if !isempty(ipv4_nonlinklocal)
+        return ipv4_nonlinklocal
+    end
+    if !isempty(ipv6_nonlinklocal)
+        return ipv6_nonlinklocal
+    end
+    if !isempty(ipv4)
+        return ipv4
+    end
+    if !isempty(ipv6)
+        return ipv6
+    end
+    return Interface[]
 end
 
 # initialize the local proc network address / port
@@ -1699,12 +1709,10 @@ function init_bind_addr()
             end
         end
     else
-        bind_port = 0
-        try
-            bind_addr = string(choose_bind_addr())
-        catch
-            # All networking is unavailable, initialize bind_addr to the loopback address
-            # Will cause an exception to be raised only when used.
+        interfaces = possible_bind_interfaces()
+        if isempty(interfaces)
+            # All networking is unavailable, initialize bind_addr to the loopback address.
+            # An exception will be raised later if even that is unavailable.
             bind_addr = "127.0.0.1"
         else
             # Pick the interface with the highest negotiated speed, if any