Add /var/log/kern.log to kernel log files.

This file is present in most distros and provides most of the logs we're
looking for. We support the others if this one is not available.

utils/oomparser/oomparser.go

@@ -16,7 +16,7 @@ package oomparser
 
 import (
 	"bufio"
-	"errors"
+	"fmt"
 	"io"
 	"os"
 	"os/exec"
@@ -187,17 +187,20 @@ func trySystemd() (*OomParser, error) {
 
 }
 
+// List of possible kernel log files. These are prioritized in order so that
+// we will use the first one that is available.
+var kernelLogFiles = []string{"/var/log/kern.log", "/var/log/messages", "/var/log/syslog"}
+
 // looks for system files that contain kernel messages and if one is found, sets
 // the systemFile attribute of the OomParser object
 func getSystemFile() (string, error) {
-	const varLogMessages = "/var/log/messages"
-	const varLogSyslog = "/var/log/syslog"
-	if utils.FileExists(varLogMessages) {
-		return varLogMessages, nil
-	} else if utils.FileExists(varLogSyslog) {
-		return varLogSyslog, nil
+	for _, logFile := range kernelLogFiles {
+		if utils.FileExists(logFile) {
+			glog.Infof("OOM parser using kernel log file: %q", logFile)
+			return logFile, nil
+		}
 	}
-	return "", errors.New("neither " + varLogSyslog + " nor " + varLogMessages + " exists from which to read kernel errors")
+	return "", fmt.Errorf("unable to find any kernel log file available from our set: %v", kernelLogFiles)
 }
 
 // initializes an OomParser object and calls getSystemFile to set the systemFile