From d169c81496b386d588fd5c25c4af34aed242d1a8 Mon Sep 17 00:00:00 2001
From: Ryan Phillips <rphillips@redhat.com>
Date: Wed, 3 Mar 2021 19:32:02 -0600
Subject: [PATCH] check log directory for restartCount

---
 .../kuberuntime/kuberuntime_container.go      | 53 +++++++++++++++++++
 .../kuberuntime/kuberuntime_container_test.go | 44 +++++++++++++++
 2 files changed, 97 insertions(+)

diff --git a/pkg/kubelet/kuberuntime/kuberuntime_container.go b/pkg/kubelet/kuberuntime/kuberuntime_container.go
index 5720576e07f..0ed4433246d 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_container.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_container.go
@@ -21,12 +21,15 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"math/rand"
 	"net/url"
 	"os"
 	"path/filepath"
+	"regexp"
 	goruntime "runtime"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -127,6 +130,40 @@ func (s *startSpec) getTargetID(podStatus *kubecontainer.PodStatus) (*kubecontai
 	return &targetStatus.ID, nil
 }
 
+func calcRestartCountByLogDir(path string) (int, error) {
+	// if the path doesn't exist then it's not an error
+	if _, err := os.Stat(path); err != nil {
+		return 0, nil
+	}
+	restartCount := int(0)
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		return 0, err
+	}
+	if len(files) == 0 {
+		return 0, err
+	}
+	restartCountLogFileRegex := regexp.MustCompile(`(\d+).log(\..*)?`)
+	for _, file := range files {
+		if file.IsDir() {
+			continue
+		}
+		matches := restartCountLogFileRegex.FindStringSubmatch(file.Name())
+		if len(matches) == 0 {
+			continue
+		}
+		count, err := strconv.Atoi(matches[1])
+		if err != nil {
+			return restartCount, err
+		}
+		count++
+		if count > restartCount {
+			restartCount = count
+		}
+	}
+	return restartCount, nil
+}
+
 // startContainer starts a container and returns a message indicates why it is failed on error.
 // It starts the container through the following steps:
 // * pull the image
@@ -150,6 +187,22 @@ func (m *kubeGenericRuntimeManager) startContainer(podSandboxID string, podSandb
 	containerStatus := podStatus.FindContainerStatusByName(container.Name)
 	if containerStatus != nil {
 		restartCount = containerStatus.RestartCount + 1
+	} else {
+		// The container runtime keeps state on container statuses and
+		// what the container restart count is. When nodes are rebooted
+		// some container runtimes clear their state which causes the
+		// restartCount to be reset to 0. This causes the logfile to
+		// start at 0.log, which either overwrites or appends to the
+		// already existing log.
+		//
+		// We are checking to see if the log directory exists, and find
+		// the latest restartCount by checking the log name -
+		// {restartCount}.log - and adding 1 to it.
+		logDir := BuildContainerLogsDirectory(pod.Namespace, pod.Name, pod.UID, container.Name)
+		restartCount, err = calcRestartCountByLogDir(logDir)
+		if err != nil {
+			klog.InfoS("Log directory exists but could not calculate restartCount", "logDir", logDir, "err", err)
+		}
 	}
 
 	target, err := spec.getTargetID(podStatus)
diff --git a/pkg/kubelet/kuberuntime/kuberuntime_container_test.go b/pkg/kubelet/kuberuntime/kuberuntime_container_test.go
index 51ad8c73c9a..1a1ae2b65e4 100644
--- a/pkg/kubelet/kuberuntime/kuberuntime_container_test.go
+++ b/pkg/kubelet/kuberuntime/kuberuntime_container_test.go
@@ -18,6 +18,8 @@ package kuberuntime
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -422,3 +424,45 @@ func TestStartSpec(t *testing.T) {
 		})
 	}
 }
+
+func TestRestartCountByLogDir(t *testing.T) {
+	for _, tc := range []struct {
+		filenames    []string
+		restartCount int
+	}{
+		{
+			filenames:    []string{"0.log.rotated-log"},
+			restartCount: 1,
+		},
+		{
+			filenames:    []string{"0.log"},
+			restartCount: 1,
+		},
+		{
+			filenames:    []string{"0.log", "1.log", "2.log"},
+			restartCount: 3,
+		},
+		{
+			filenames:    []string{"0.log.rotated", "1.log", "2.log"},
+			restartCount: 3,
+		},
+		{
+			filenames:    []string{"5.log.rotated", "6.log.rotated"},
+			restartCount: 7,
+		},
+		{
+			filenames:    []string{"5.log.rotated", "6.log", "7.log"},
+			restartCount: 8,
+		},
+	} {
+		tempDirPath, err := ioutil.TempDir("", "test-restart-count-")
+		assert.NoError(t, err, "create tempdir error")
+		defer os.RemoveAll(tempDirPath)
+		for _, filename := range tc.filenames {
+			err = ioutil.WriteFile(filepath.Join(tempDirPath, filename), []byte("a log line"), 0600)
+			assert.NoError(t, err, "could not write log file")
+		}
+		count, _ := calcRestartCountByLogDir(tempDirPath)
+		assert.Equal(t, count, tc.restartCount, "count %v should equal restartCount %v", count, tc.restartCount)
+	}
+}