kubelet.go

/*
Copyright 2016 The Kubernetes Authors.

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 services

import (
	"flag"
	"fmt"
	"io/ioutil"
	"math/rand"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/golang/glog"

	"k8s.io/kubernetes/test/e2e/framework"
	"k8s.io/kubernetes/test/e2e_node/builder"
)

// TODO(random-liu): Replace this with standard kubelet launcher.

// args is the type used to accumulate args from the flags with the same name.
type args []string

// String function of flag.Value
func (a *args) String() string {
	return fmt.Sprint(*a)
}

// Set function of flag.Value
func (a *args) Set(value string) error {
	// Someone else is calling flag.Parse after the flags are parsed in the
	// test framework. Use this to avoid the flag being parsed twice.
	// TODO(random-liu): Figure out who is parsing the flags.
	if flag.Parsed() {
		return nil
	}
	// Note that we assume all white space in flag string is separating fields
	na := strings.Fields(value)
	*a = append(*a, na...)
	return nil
}

// kubeletArgs is the override kubelet args specified by the test runner.
var kubeletArgs args

func init() {
	flag.Var(&kubeletArgs, "kubelet-flags", "Kubelet flags passed to kubelet, this will override default kubelet flags in the test. Flags specified in multiple kubelet-flags will be concatenate.")
}

// RunKubelet starts kubelet and waits for termination signal. Once receives the
// termination signal, it will stop the kubelet gracefully.
func RunKubelet() {
	var err error
	// Enable monitorParent to make sure kubelet will receive termination signal
	// when test process exits.
	e := NewE2EServices(true /* monitorParent */)
	defer e.Stop()
	e.kubelet, err = e.startKubelet()
	if err != nil {
		glog.Fatalf("Failed to start kubelet: %v", err)
	}
	// Wait until receiving a termination signal.
	waitForTerminationSignal()
}

const (
	// Ports of different e2e services.
	kubeletPort         = "10250"
	kubeletReadOnlyPort = "10255"
	// Health check url of kubelet
	kubeletHealthCheckURL = "http://127.0.0.1:" + kubeletReadOnlyPort + "/healthz"
)

// startKubelet starts the Kubelet in a separate process or returns an error
// if the Kubelet fails to start.
func (e *E2EServices) startKubelet() (*server, error) {
	glog.Info("Starting kubelet")
	// Create pod manifest path
	manifestPath, err := createPodManifestDirectory()
	if err != nil {
		return nil, err
	}
	e.rmDirs = append(e.rmDirs, manifestPath)
	var killCommand, restartCommand *exec.Cmd
	var isSystemd bool
	// Apply default kubelet flags.
	cmdArgs := []string{}
	if systemdRun, err := exec.LookPath("systemd-run"); err == nil {
		// On systemd services, detection of a service / unit works reliably while
		// detection of a process started from an ssh session does not work.
		// Since kubelet will typically be run as a service it also makes more
		// sense to test it that way
		isSystemd = true
		unitName := fmt.Sprintf("kubelet-%d.service", rand.Int31())
		cmdArgs = append(cmdArgs, systemdRun, "--unit="+unitName, "--slice=runtime.slice", "--remain-after-exit", builder.GetKubeletServerBin())
		killCommand = exec.Command("systemctl", "kill", unitName)
		restartCommand = exec.Command("systemctl", "restart", unitName)
		e.logFiles["kubelet.log"] = logFileData{
			journalctlCommand: []string{"-u", unitName},
		}
		cmdArgs = append(cmdArgs,
			"--kubelet-cgroups=/kubelet.slice",
			"--cgroup-root=/",
		)
	} else {
		cmdArgs = append(cmdArgs, builder.GetKubeletServerBin())
		cmdArgs = append(cmdArgs,
			"--runtime-cgroups=/docker-daemon",
			"--kubelet-cgroups=/kubelet",
			"--cgroup-root=/",
			"--system-cgroups=/system",
		)
	}
	cmdArgs = append(cmdArgs,
		"--api-servers", getAPIServerClientURL(),
		"--address", "0.0.0.0",
		"--port", kubeletPort,
		"--read-only-port", kubeletReadOnlyPort,
		"--volume-stats-agg-period", "10s", // Aggregate volumes frequently so tests don't need to wait as long
		"--allow-privileged", "true",
		"--serialize-image-pulls", "false",
		"--pod-manifest-path", manifestPath,
		"--file-check-frequency", "10s", // Check file frequently so tests won't wait too long
		"--pod-cidr", "10.180.0.0/24", // Assign a fixed CIDR to the node because there is no node controller.
		"--eviction-pressure-transition-period", "30s",
		// Apply test framework feature gates by default. This could also be overridden
		// by kubelet-flags.
		"--feature-gates", framework.TestContext.FeatureGates,
		"--eviction-hard", "memory.available<250Mi,nodefs.available<10%,nodefs.inodesFree<5%", // The hard eviction thresholds.
		"--eviction-minimum-reclaim", "nodefs.available=5%,nodefs.inodesFree=5%", // The minimum reclaimed resources after eviction.
		"--v", LOG_VERBOSITY_LEVEL, "--logtostderr",
	)
	// Enable kubenet by default.
	cniDir, err := getCNIDirectory()
	if err != nil {
		return nil, err
	}
	cmdArgs = append(cmdArgs,
		"--network-plugin=kubenet",
		"--network-plugin-dir", cniDir)

	// Keep hostname override for convenience.
	if framework.TestContext.NodeName != "" { // If node name is specified, set hostname override.
		cmdArgs = append(cmdArgs, "--hostname-override", framework.TestContext.NodeName)
	}

	// Override the default kubelet flags.
	cmdArgs = append(cmdArgs, kubeletArgs...)

	// Adjust the args if we are running kubelet with systemd.
	if isSystemd {
		adjustArgsForSystemd(cmdArgs)
	}

	cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
	server := newServer(
		"kubelet",
		cmd,
		killCommand,
		restartCommand,
		[]string{kubeletHealthCheckURL},
		"kubelet.log",
		e.monitorParent,
		true /* restartOnExit */)
	return server, server.start()
}

// createPodManifestDirectory creates pod manifest directory.
func createPodManifestDirectory() (string, error) {
	cwd, err := os.Getwd()
	if err != nil {
		return "", fmt.Errorf("failed to get current working directory: %v", err)
	}
	path, err := ioutil.TempDir(cwd, "pod-manifest")
	if err != nil {
		return "", fmt.Errorf("failed to create static pod manifest directory: %v", err)
	}
	return path, nil
}

// getCNIDirectory returns CNI directory.
func getCNIDirectory() (string, error) {
	cwd, err := os.Getwd()
	if err != nil {
		return "", err
	}
	// TODO(random-liu): Make sure the cni directory name is the same with that in remote/remote.go
	return filepath.Join(cwd, "cni", "bin"), nil
}

// adjustArgsForSystemd escape special characters in kubelet arguments for systemd. Systemd
// may try to do auto expansion without escaping.
func adjustArgsForSystemd(args []string) {
	for i := range args {
		args[i] = strings.Replace(args[i], "%", "%%", -1)
		args[i] = strings.Replace(args[i], "$", "$$", -1)
	}
}