Add health-check-monitor

2026-08-23 22:26:27 +00:00 · 2020-05-27 14:08:42 -07:00
parent 1d03b66f15
commit 44dc4aa6c1
9 changed files with 630 additions and 2 deletions
@@ -0,0 +1,163 @@
+/*
+Copyright 2020 The Kubernetes Authors All rights reserved.
+
+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 healthchecker
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"os/exec"
+	"strings"
+	"time"
+
+	"github.com/golang/glog"
+
+	"k8s.io/node-problem-detector/cmd/healthchecker/options"
+	"k8s.io/node-problem-detector/pkg/healthchecker/types"
+)
+
+type healthChecker struct {
+	enableRepair    bool
+	healthCheckFunc func() bool
+	// The repair is "best-effort" and ignores the error from the underlying actions.
+	// The bash commands to kill the process will fail if the service is down and hence ignore.
+	repairFunc         func()
+	uptimeFunc         func() (time.Duration, error)
+	crictlPath         string
+	healthCheckTimeout time.Duration
+	coolDownTime       time.Duration
+}
+
+// NewHealthChecker returns a new health checker configured with the given options.
+func NewHealthChecker(hco *options.HealthCheckerOptions) (types.HealthChecker, error) {
+	hc := &healthChecker{
+		enableRepair:       hco.EnableRepair,
+		crictlPath:         hco.CriCtlPath,
+		healthCheckTimeout: hco.HealthCheckTimeout,
+		coolDownTime:       hco.CoolDownTime,
+	}
+	hc.healthCheckFunc = getHealthCheckFunc(hco)
+	hc.repairFunc = getRepairFunc(hco)
+	hc.uptimeFunc = getUptimeFunc(hco.SystemdService)
+	return hc, nil
+}
+
+// getUptimeFunc returns the time for which the given service has been running.
+func getUptimeFunc(service string) func() (time.Duration, error) {
+	return func() (time.Duration, error) {
+		out, err := execCommand(types.CmdTimeout, "systemctl", "show", service, "--property=ActiveEnterTimestamp")
+		if err != nil {
+			return time.Duration(0), err
+		}
+		val := strings.Split(out, "=")
+		if len(val) < 2 {
+			return time.Duration(0), errors.New("could not parse the service uptime time correctly")
+		}
+		t, err := time.Parse(types.UptimeTimeLayout, val[1])
+		if err != nil {
+			return time.Duration(0), err
+		}
+		return time.Since(t), nil
+	}
+}
+
+// getRepairFunc returns the repair function based on the component.
+func getRepairFunc(hco *options.HealthCheckerOptions) func() {
+	switch hco.Component {
+	case types.DockerComponent:
+		// Use "docker ps" for docker health check. Not using crictl for docker to remove
+		// dependency on the kubelet.
+		return func() {
+			execCommand(types.CmdTimeout, "pkill", "-SIGUSR1", "dockerd")
+			execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.SystemdService)
+		}
+	default:
+		// Just kill the service for all other components
+		return func() {
+			execCommand(types.CmdTimeout, "systemctl", "kill", "--kill-who=main", hco.SystemdService)
+		}
+	}
+}
+
+// getHealthCheckFunc returns the health check function based on the component.
+func getHealthCheckFunc(hco *options.HealthCheckerOptions) func() bool {
+	switch hco.Component {
+	case types.KubeletComponent:
+		return func() bool {
+			httpClient := http.Client{Timeout: hco.HealthCheckTimeout}
+			response, err := httpClient.Get(types.KubeletHealthCheckEndpoint)
+			if err != nil || response.StatusCode != http.StatusOK {
+				return false
+			}
+			return true
+		}
+	case types.DockerComponent:
+		return func() bool {
+			if _, err := execCommand(hco.HealthCheckTimeout, "docker", "ps"); err != nil {
+				return false
+			}
+			return true
+		}
+	case types.CRIComponent:
+		return func() bool {
+			if _, err := execCommand(hco.HealthCheckTimeout, hco.CriCtlPath, "--runtime-endpoint="+hco.CriSocketPath, "--image-endpoint="+hco.CriSocketPath, "pods"); err != nil {
+				return false
+			}
+			return true
+		}
+	}
+	return nil
+}
+
+// CheckHealth checks for the health of the component and tries to repair if enabled.
+// Returns true if healthy, false otherwise.
+func (hc *healthChecker) CheckHealth() bool {
+	healthy := hc.healthCheckFunc()
+	if healthy {
+		return true
+	}
+	// The service is unhealthy.
+	// Attempt repair based on flag.
+	if hc.enableRepair {
+		glog.Infof("health-checker: component is unhealthy, proceeding to repair")
+		// repair if the service has been up for the cool down period.
+		uptime, err := hc.uptimeFunc()
+		if err != nil {
+			glog.Infof("health-checker: %v\n", err.Error())
+		}
+		glog.Infof("health-checker: component uptime: %v\n", uptime)
+		if uptime > hc.coolDownTime {
+			hc.repairFunc()
+		}
+	}
+	return false
+}
+
+// execCommand executes the bash command and returns the (output, error) from command, error if timeout occurs.
+func execCommand(timeout time.Duration, command string, args ...string) (string, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, command, args...)
+	glog.Infof("health-checker: executing command : %v\n", cmd)
+	out, err := cmd.Output()
+	if err != nil {
+		glog.Infof("health-checker: command failed : %v, %v\n", err.Error(), out)
+		return "", err
+	}
+	return strings.TrimSuffix(string(out), "\n"), nil
+}
@@ -0,0 +1,118 @@
+/*
+Copyright 2020 The Kubernetes Authors All rights reserved.
+
+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 healthchecker
+
+import (
+	"testing"
+	"time"
+
+	"k8s.io/node-problem-detector/pkg/healthchecker/types"
+)
+
+var repairCalled bool
+
+func NewTestHealthChecker(repairFunc func(), healthCheckFunc func() bool, uptimeFunc func() (time.Duration, error), enableRepair bool) types.HealthChecker {
+	repairCalled = false
+	return &healthChecker{
+		enableRepair:       enableRepair,
+		healthCheckFunc:    healthCheckFunc,
+		repairFunc:         repairFunc,
+		uptimeFunc:         uptimeFunc,
+		healthCheckTimeout: time.Second,
+		coolDownTime:       2 * time.Second,
+	}
+}
+
+func healthyFunc() bool {
+	return true
+}
+
+func unhealthyFunc() bool {
+	return false
+}
+
+func repairFunc() {
+	repairCalled = true
+}
+
+func longServiceUptimeFunc() (time.Duration, error) {
+	return 1 * time.Hour, nil
+}
+
+func shortServiceUptimeFunc() (time.Duration, error) {
+	return 1 * time.Second, nil
+}
+
+func TestHealthCheck(t *testing.T) {
+	for _, tc := range []struct {
+		description     string
+		enableRepair    bool
+		healthy         bool
+		healthCheckFunc func() bool
+		uptimeFunc      func() (time.Duration, error)
+		repairFunc      func()
+		repairCalled    bool
+	}{
+		{
+			description:     "healthy component",
+			enableRepair:    true,
+			healthy:         true,
+			healthCheckFunc: healthyFunc,
+			repairFunc:      repairFunc,
+			uptimeFunc:      shortServiceUptimeFunc,
+			repairCalled:    false,
+		},
+		{
+			description:     "unhealthy component and disabled repair",
+			enableRepair:    false,
+			healthy:         false,
+			healthCheckFunc: unhealthyFunc,
+			repairFunc:      repairFunc,
+			uptimeFunc:      shortServiceUptimeFunc,
+			repairCalled:    false,
+		},
+		{
+			description:     "unhealthy component, enabled repair and component in cool dowm",
+			enableRepair:    true,
+			healthy:         false,
+			healthCheckFunc: unhealthyFunc,
+			repairFunc:      repairFunc,
+			uptimeFunc:      shortServiceUptimeFunc,
+			repairCalled:    false,
+		},
+		{
+			description:     "unhealthy component, enabled repair and component out of cool dowm",
+			enableRepair:    true,
+			healthy:         false,
+			healthCheckFunc: unhealthyFunc,
+			repairFunc:      repairFunc,
+			uptimeFunc:      longServiceUptimeFunc,
+			repairCalled:    true,
+		},
+	} {
+		t.Run(tc.description, func(t *testing.T) {
+			hc := NewTestHealthChecker(tc.repairFunc, tc.healthCheckFunc, tc.uptimeFunc, tc.enableRepair)
+			healthy := hc.CheckHealth()
+			if healthy != tc.healthy {
+				t.Errorf("incorrect health returned got %t; expected %t", healthy, tc.healthy)
+			}
+			if repairCalled != tc.repairCalled {
+				t.Errorf("incorrect repairCalled got %t; expected %t", repairCalled, tc.repairCalled)
+			}
+		})
+	}
+}
@@ -0,0 +1,37 @@
+/*
+Copyright 2020 The Kubernetes Authors All rights reserved.
+
+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 types
+
+import "time"
+
+const (
+	DefaultCoolDownTime        = 2 * time.Minute
+	DefaultHealthCheckTimeout  = 10 * time.Second
+	CmdTimeout                 = 10 * time.Second
+	DefaultCriCtl              = "/usr/bin/crictl"
+	DefaultCriSocketPath       = "unix:///var/run/containerd/containerd.sock"
+	KubeletComponent           = "kubelet"
+	CRIComponent               = "cri"
+	DockerComponent            = "docker"
+	ContainerdService          = "containerd"
+	KubeletHealthCheckEndpoint = "http://127.0.0.1:10248/healthz"
+	UptimeTimeLayout           = "Mon 2006-01-02 15:04:05 UTC"
+)
+
+type HealthChecker interface {
+	CheckHealth() bool
+}