ci: fail an S3 benchmark run on EC2 without a local instance store

Without an instance store the Raft Engine WAL of the R cells silently stayed
on the root EBS volume, so the run measured a different baseline. Only a smoke
run may keep it on the root volume now.

Signed-off-by: jeremyhi <fengjiachun@gmail.com>

.github/scripts/oswal-s3-bench-run.sh

@@ -33,6 +33,8 @@ pull_images() {
 wal_disk() {
     local root=$1 device
     device=$(lsblk -dnpo NAME,MODEL | awk '/Instance Storage/ {print $1; exit}')
+    # Only a smoke run may keep the Raft Engine WAL on the root volume.
+    [[ -n "$device" || "${SMOKE:-}" == true ]] || { echo 'No local NVMe instance store; choose an instance type with one' >&2; return 1; }
     sudo -n mkdir -p "$root"
     if [[ -n "$device" ]]; then
         sudo -n umount "$device" 2>/dev/null || true

tests/perf/test_oswal_s3_bench_scripts.py

@@ -264,6 +264,16 @@ class CellLifecycleTest(unittest.TestCase):  # the run script against fake docke
             self.assertEqual(log.count("docker stop -t 120 fakecid"), 2)
             self.assertEqual(log.count("docker rm -fv fakecid"), 2)
 
+    def test_an_ec2_run_without_an_instance_store_fails(self):
+        with tempfile.TemporaryDirectory() as directory:
+            (Path(directory) / "lsblk").write_text("#!/usr/bin/env bash\necho '/dev/nvme0n1 Amazon Elastic Block Store'\n")
+            (Path(directory) / "lsblk").chmod(0o755)
+            env = os.environ | {"PATH": f"{directory}:{os.environ['PATH']}", "SMOKE": "false"}
+            done = subprocess.run(["bash", str(SCRIPTS / "oswal-s3-bench-run.sh"), "wal-disk", f"{directory}/wal"],
+                                  env=env, capture_output=True, text=True, timeout=60)
+            self.assertNotEqual(done.returncode, 0)
+            self.assertIn("No local NVMe instance store", done.stderr)
+
     def test_a_failed_scrape_fails_a_successful_load(self):
         with tempfile.TemporaryDirectory() as directory:
             root = Path(directory)