fix(golden-image): add kernel-modules-extra to container disk image

build/golden-image/Containerfile

@@ -21,6 +21,7 @@ RUN dnf install -y \
     postgresql-server \
     iproute-tc \
     iptables-nft \
+    kernel-modules-extra \
     netperf \
     python3 \
     && dnf clean all \

build/golden-image/README.md

@@ -15,7 +15,8 @@ The golden image is based on `quay.io/containerdisks/fedora:41` and includes all
 - **python3** — HTTP file server for the tps workload's application-layer transfers
 - **postgresql-server** — PostgreSQL database with pgbench (database workload)
 - **procps-ng** — `ps`, `pkill`, `kill` for chaos-process
-- **iproute-tc** — Traffic control (`tc`) and the `sch_netem` kernel module hooks used by the chaos-network workload to inject latency and packet loss
+- **iproute-tc** — Traffic control (`tc`) used by the chaos-network workload to inject latency and packet loss
+- **kernel-modules-extra** — Provides the `sch_netem` kernel module required by chaos-network; pre-installing means the cloud-init `dnf install` completes instantly (package already present) instead of fetching over the network
 - **iptables-nft** — Firewall rules; reserved for future network partition / blackhole scenarios
 
 Additional tools like `fallocate` and `dd` (used by chaos-disk) are already present in the base Fedora image.

docs/chaos-workloads.md

@@ -133,7 +133,7 @@ workloads:
 
 ### Dependencies
 
-The workload installs `iproute-tc` and loads the `sch_netem` kernel module on start. The base Fedora container disk has both available; the golden image (`build/golden-image/`) pre-installs `iproute-tc` to avoid the first-boot package install. `sch_netem` is loaded from the `kernel-modules-extra` package, which the cloud-init runs `dnf install` for on first boot.
+The workload requires `iproute-tc` and the `sch_netem` kernel module. The golden image (`build/golden-image/`) pre-installs both `iproute-tc` and `kernel-modules-extra` (which provides `sch_netem`), so the cloud-init `dnf install` completes instantly (package already present) and no network fetch is needed. On the default Fedora container disk, cloud-init installs `iproute-tc` via `packages` and `kernel-modules-extra-$(uname -r)` via `runcmd`, which ensures the module version matches the running kernel. The start script runs `modprobe sch_netem` to load the module before applying the qdisc.
 
 ### Example
 

internal/workloads/chaos_network.go

@@ -92,7 +92,8 @@ func (w *ChaosNetworkWorkload) Name() string {
 }
 
 // CloudInitUserdata returns cloud-init YAML that configures tc/netem for network chaos
-// injection via systemd. Assumes iproute-tc is pre-installed (golden image dependency).
+// injection via systemd. The golden image pre-installs iproute-tc and kernel-modules-extra
+// (sch_netem); the start script runs modprobe as a fallback for non-golden images.
 func (w *ChaosNetworkWorkload) CloudInitUserdata() (string, error) {
 	startScript := fmt.Sprintf(chaosNetworkStartScript,
 		w.latencyMs(),

internal/workloads/chaos_network_test.go

@@ -4,6 +4,8 @@
 package workloads_test
 
 import (
+	"strings"
+
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
 
@@ -72,32 +74,30 @@ var _ = Describe("ChaosNetworkWorkload", func() {
 		Expect(parsed).To(HaveKey("runcmd"))
 		runcmds := parsed["runcmd"].([]interface{})
 
-		foundKernelModules := false
+		foundDnf := false
+		foundDaemonReload := false
 		foundEnable := false
-		kernelModulesIdx := -1
-		enableIdx := -1
-		for i, cmd := range runcmds {
+		for _, cmd := range runcmds {
 			cmdSlice := cmd.([]interface{})
-			if len(cmdSlice) >= 3 {
-				if cmdSlice[0] == "bash" && cmdSlice[1] == "-c" {
-					cmdStr := cmdSlice[2].(string)
-					if cmdStr == "dnf install -y kernel-modules-extra-$(uname -r)" {
-						foundKernelModules = true
-						kernelModulesIdx = i
-					}
-				}
-				if cmdSlice[0] == "systemctl" && cmdSlice[1] == "enable" {
-					foundEnable = true
-					enableIdx = i
-					Expect(cmdSlice[2]).To(Equal("--now"))
+			if len(cmdSlice) >= 3 && cmdSlice[0] == "bash" && cmdSlice[1] == "-c" {
+				script, _ := cmdSlice[2].(string)
+				if strings.Contains(script, "kernel-modules-extra") {
+					foundDnf = true
+					Expect(script).To(ContainSubstring("$(uname -r)"),
+						"should install kernel-modules-extra matching the running kernel")
 				}
 			}
+			if len(cmdSlice) >= 2 && cmdSlice[0] == "systemctl" && cmdSlice[1] == "daemon-reload" {
+				foundDaemonReload = true
+			}
+			if len(cmdSlice) >= 3 && cmdSlice[0] == "systemctl" && cmdSlice[1] == "enable" {
+				foundEnable = true
+				Expect(cmdSlice[2]).To(Equal("--now"))
+			}
 		}
-		Expect(foundKernelModules).To(BeTrue(), "should install kernel-modules-extra for running kernel")
-		Expect(foundEnable).To(BeTrue(), "should have systemctl enable command")
-		Expect(kernelModulesIdx).To(
-			BeNumerically("<", enableIdx),
-			"kernel modules install should come before service enable")
+		Expect(foundDnf).To(BeTrue(), "should have dnf install kernel-modules-extra")
+		Expect(foundDaemonReload).To(BeTrue(), "should have systemctl daemon-reload")
+		Expect(foundEnable).To(BeTrue(), "should have systemctl enable --now")
 	})
 
 	It("should produce valid YAML", func() {