test: add multi-node k8s test script for cross-node gRPC transfers

- workspace-tests/tests/k8s_multinode_tests.rs: Rust integration tests using
  the kube crate, all #[ignore] by default. 5 tests:
  - Cross-node gRPC transfer (default, 64KB, 4MB chunk sizes)
  - Transfer integrity with md5 content hash comparison
  - Multi-replica independent cache verification
- test_multinode_k8s.sh: minimal wrapper that builds the Docker image,
  distributes it via microk8s images import, and runs cargo test
- Adds kube ws feature and anyhow to workspace-tests dependencies

Signed-off-by: Nicolas 'Pixel' Noble <nicolas@nobis-crew.org>

Author: nicolasnoble

Cargo.lock

@@ -0,0 +1,59 @@
+#!/bin/bash
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+# Build the ModelExpress Docker image, distribute it to all cluster nodes,
+# and run the multi-node Kubernetes integration tests.
+#
+# The actual test logic lives in workspace-tests/tests/k8s_multinode_tests.rs.
+# This script only handles image preparation, which can't be done from Rust.
+#
+# Prerequisites:
+#   - Docker
+#   - A multi-node Kubernetes cluster (at least 2 schedulable nodes) with kubeconfig accessible
+#   - The modelexpress:multinode-test image must be available on all cluster nodes
+#
+# Image distribution:
+#   - microk8s: auto-detected, uses `microk8s images import` to distribute to all nodes
+#   - Other clusters: push the image to your registry and ensure nodes can pull it,
+#     or use your cluster's image distribution mechanism. Use --skip-build to skip
+#     the Docker build step if the image is already available.
+#
+# The tests themselves are cluster-agnostic: they discover nodes dynamically via
+# the Kubernetes API and only require standard kubeconfig access.
+#
+# Usage:
+#   ./test_multinode_k8s.sh [--skip-build] [-- cargo test args...]
+#
+# Examples:
+#   ./test_multinode_k8s.sh                              # Build + run all tests
+#   ./test_multinode_k8s.sh --skip-build                 # Skip image build, just run tests
+#   ./test_multinode_k8s.sh -- --test cross_node         # Run only cross_node tests
+
+set -e
+cd "$(dirname "$0")"
+
+SKIP_BUILD=false
+CARGO_ARGS=()
+
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        --skip-build) SKIP_BUILD=true; shift ;;
+        --) shift; CARGO_ARGS=("$@"); break ;;
+        *) CARGO_ARGS=("$@"); break ;;
+    esac
+done
+
+# Step 1: Build and distribute image
+if [ "$SKIP_BUILD" = false ]; then
+    echo "Building Docker image modelexpress:multinode-test..."
+    docker build -t modelexpress:multinode-test .
+
+    if command -v /snap/bin/microk8s &>/dev/null; then
+        echo "Distributing image to microk8s cluster nodes..."
+        docker save modelexpress:multinode-test | /snap/bin/microk8s images import -
+    fi
+fi
+
+# Step 2: Run the Rust k8s tests (ignored by default, --ignored enables them)
+cargo test --test k8s_multinode_tests -- --ignored "${CARGO_ARGS[@]}"

test_multinode_k8s.sh

@@ -22,6 +22,9 @@ serde_json = { workspace = true }
 tempfile = { workspace = true }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true }
+kube = { workspace = true, features = ["ws"] }
+k8s-openapi = { workspace = true }
+anyhow = { workspace = true }
 
 [dev-dependencies]
 criterion = { version = "0.6", features = ["html_reports"] }