kola/switch-kernel: test for switching between rt and default kernel

Supports --rpm-dir option for uploading the rt kernel rpms into the
cluster machine and adds a test that switches to target kernel with rpm-ostree, using logic
defined in https://github.com/openshift/machine-config-operator/blob/f363c7be6d2d506d900e196fa2e2d05ca08b93b6/pkg/daemon/update.go#L651.

Closes: https://issues.redhat.com/browse/GRPA-1439
Signed-off-by: Allen Bai <abai@redhat.com>

mantle/kola/tests/rhcos/switch-kernel.go

@@ -0,0 +1,167 @@
+// Copyright 2020 Red Hat, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package rhcos
+
+import (
+	"encoding/base64"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"regexp"
+
+	"github.com/coreos/mantle/kola/cluster"
+	"github.com/coreos/mantle/kola/register"
+	"github.com/coreos/mantle/platform"
+	"github.com/coreos/mantle/platform/conf"
+	"github.com/pkg/errors"
+)
+
+var (
+	homeDir = `/var/home/core`
+	switchKernelScript = `#!/usr/bin/env bash
+	# This script is a shameless translation of: https://github.com/openshift/machine-config-operator/blob/f363c7be6d2d506d900e196fa2e2d05ca08b93b6/pkg/daemon/update.go#L651
+	# Usage:
+	# switch-kernel oldkernel newkernel rt-kernel-repo
+	# {oldkernel, newkernel}: either of {default, rt-kernel}
+	# rt-kernel-repo (optional): repository of kernel-rt packages
+	set -xeuo pipefail
+	
+	FROM_KERNEL="${1:?old kernel should be either of \{default, rt-kernel\}}"
+	TO_KERNEL="${2:?new kernel should be either of \{default, rt-kernel\}}"
+	
+	DEFAULT_KERNEL_PKG="kernel kernel-core kernel-modules kernel-modules-extra"
+	RT_KERNEL_PKG="kernel-rt-core kernel-rt-modules kernel-rt-modules-extra"
+	
+	if [[ $FROM_KERNEL == "default" && $TO_KERNEL == "rt-kernel" ]]; then
+		# Switch from default to RT Kernel
+		# https://github.com/openshift/machine-config-operator/blob/master/pkg/daemon/update.go#L711
+		RT_KERNEL_REPO=$3
+		if [[ -z $(ls ${RT_KERNEL_REPO}) ]]; then
+			echo "No kernel-rt package available in the repo: ${RT_KERNEL_REPO}"
+			exit 1
+		fi
+	
+		ARGS="override remove ${DEFAULT_KERNEL_PKG}"
+		for RPM in $(ls ${RT_KERNEL_REPO})
+		do
+			ARGS+=" --install ${RT_KERNEL_REPO}/${RPM}"
+		done
+		rpm-ostree ${ARGS}
+	elif [[ $FROM_KERNEL == "rt-kernel" && $TO_KERNEL == "default" ]]; then
+		# Switch from RT Kernel to default
+		# https://github.com/openshift/machine-config-operator/blob/e246be62e7839a086bc4494203472349c406dcae/pkg/daemon/update.go#L667
+		ARGS="override reset ${DEFAULT_KERNEL_PKG}"
+		for PKG in $RT_KERNEL_PKG
+		do
+			ARGS+=" --uninstall $PKG"
+		done
+		rpm-ostree ${ARGS}
+	else
+		echo -e "Invalid options: $@" && exit 1
+	fi
+	`
+)
+
+func init() {
+	register.RegisterTest(&register.Test{
+		Run:         testSwitchKernel,
+		ClusterSize: 1,
+		Name:        `rhcos.switch-kernel`,
+		Flags:       []register.Flag{},
+		Distros:     []string{"rhcos"},
+		Platforms:   []string{"qemu"},
+		UserData: conf.Ignition(fmt.Sprintf(`{
+			"ignition": {
+				"version": "2.2.0"
+			},
+			"storage": {
+				"files": [
+					{
+						"filesystem": "root",
+						"path": "/var/home/core/switch-kernel.sh",
+						"contents": {
+							"source": "data:text/plain;base64,%s"
+						},
+						"mode": 110
+					}
+				]
+			}
+		}`, base64.StdEncoding.EncodeToString([]byte(switchKernelScript)))),
+	})
+}
+
+// Drops Kernel RT RPM files under the directory `localPath` to `$homeDir/kernel-rt-rpms` directory in m
+func dropRpmFilesAll(m platform.Machine, localPath string) error {
+	re := regexp.MustCompile(`^kernel-rt-.*\.rpm$`)
+	files, err := ioutil.ReadDir(localPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, f := range files {
+		filename := f.Name()
+		filepath := localPath + filename
+		targetPath := fmt.Sprintf("%s/kernel-rt-rpms/%s", homeDir, filename)
+		if re.MatchString(filename) {
+			in, err := os.Open(filepath)
+			if err != nil {
+				return err
+			}
+			if err := platform.InstallFile(in, m, targetPath); err != nil {
+				return errors.Wrapf(err, "uploading %s", filename)
+			}
+		}
+	}
+	return nil
+}
+
+func switchDefaultToRtKernel(c cluster.TestCluster, m platform.Machine) {
+	// run the script to switch from default kernel to rt kernel
+	c.MustSSH(m, "sudo "+homeDir+"/switch-kernel.sh default rt-kernel "+homeDir+"/kernel-rt-rpms/")
+
+	// reboot the machine to switch kernel
+	err := m.Reboot()
+	if err != nil {
+		c.Fatalf("Could not reboot machine: %v", err)
+	}
+
+	// check if the kernel has switched to rt kernel
+	c.MustSSH(m, "uname -v | grep -q 'PREEMPT RT'")
+}
+
+func switchRtKernelToDefault(c cluster.TestCluster, m platform.Machine) {
+	// run the script to switch from rt kernel to default
+	c.MustSSH(m, "sudo "+homeDir+"/switch-kernel.sh rt-kernel default")
+
+	// reboot the machine to switch kernel
+	err := m.Reboot()
+	if err != nil {
+		c.Fatalf("Could not reboot machine: %v", err)
+	}
+
+	// check if the kernel has switched back to default kernel
+	c.MustSSH(m, "! $(uname -v | grep -q 'PREEMPT RT')")
+}
+
+func testSwitchKernel(c cluster.TestCluster) {
+	m := c.Machines()[0]
+	kernelRtRpmDir := "/srv/kernel-rt/"
+	err := dropRpmFilesAll(m, kernelRtRpmDir)
+	if err != nil {
+		c.Fatal("Failed dropping Kernel RT RPM files: %v", err)
+	}
+	switchDefaultToRtKernel(c, m)
+	switchRtKernelToDefault(c, m)
+}