How can I get log4j to delete old rotating log files? - log4j

Question

How can I get log4j to delete old rotating log files? I know I can set up automated jobs (cron for UNIX and scheduled task for Windows), but I want it cross platform, and I want it in our application's log configuration as a part of our application, rather than in separate code outside in OS specific scripting languages. Our application is not written in OS scripting languages, and I don't want to do this part of it in them.

Answer 1

RollingFileAppender does this. You just need to set maxBackupIndex to the highest value for the backup file.

Answer 2

Logs rotate for a reason, so that you only keep so many log files around. In log4j.xml you can add this to your node:
<param name="MaxBackupIndex" value="20"/>
The value tells log4j.xml to only keep 20 rotated log files around. You can limit this to 5 if you want or even 1. If your application isn't logging that much data, and you have 20 log files spanning the last 8 months, but you only need a weeks worth of logs, then I think you need to tweak your log4j.xml "MaxBackupIndex" and "MaxFileSize" params.
Alternatively, if you are using a properties file (instead of the xml) and wish to save 15 files (for example)
log4j.appender.[appenderName].MaxBackupIndex = 15

Answer 3

There is no default value to control deleting old log files created by DailyRollingFileAppender. But you can write your own custom Appender that deletes old log files in much the same way as setting maxBackupIndex does for RollingFileAppender.
Simple instructions found here
From 1:
If you are trying to use the Apache Log4J DailyRollingFileAppender for a daily log file, you may need to want to specify the maximum number of files which should be kept. Just like rolling RollingFileAppender supports maxBackupIndex. But the current version of Log4j (Apache log4j 1.2.16) does not provide any mechanism to delete old log files if you are using DailyRollingFileAppender. I tried to make small modifications in the original version of DailyRollingFileAppender to add maxBackupIndex property. So, it would be possible to clean up old log files which may not be required for future usage.

Answer 4

You can achieve it using custom log4j appender.
MaxNumberOfDays - possibility to set amount of days of rotated log files.
CompressBackups - possibility to archive old logs with zip extension.
package com.example.package;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;
import java.io.File;
import java.io.FileFilter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.Optional;
import java.util.TimeZone;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
public class CustomLog4jAppender extends FileAppender {
private static final int TOP_OF_TROUBLE = -1;
private static final int TOP_OF_MINUTE = 0;
private static final int TOP_OF_HOUR = 1;
private static final int HALF_DAY = 2;
private static final int TOP_OF_DAY = 3;
private static final int TOP_OF_WEEK = 4;
private static final int TOP_OF_MONTH = 5;
private String datePattern = "'.'yyyy-MM-dd";
private String compressBackups = "false";
private String maxNumberOfDays = "7";
private String scheduledFilename;
private long nextCheck = System.currentTimeMillis() - 1;
private Date now = new Date();
private SimpleDateFormat sdf;
private RollingCalendar rc = new RollingCalendar();
private static final TimeZone gmtTimeZone = TimeZone.getTimeZone("GMT");
public CustomLog4jAppender() {
}
public CustomLog4jAppender(Layout layout, String filename, String datePattern) throws IOException {
super(layout, filename, true);
this.datePattern = datePattern;
activateOptions();
}
public void setDatePattern(String pattern) {
datePattern = pattern;
}
public String getDatePattern() {
return datePattern;
}
#Override
public void activateOptions() {
super.activateOptions();
if (datePattern != null && fileName != null) {
now.setTime(System.currentTimeMillis());
sdf = new SimpleDateFormat(datePattern);
int type = computeCheckPeriod();
printPeriodicity(type);
rc.setType(type);
File file = new File(fileName);
scheduledFilename = fileName + sdf.format(new Date(file.lastModified()));
} else {
LogLog.error("Either File or DatePattern options are not set for appender [" + name + "].");
}
}
private void printPeriodicity(int type) {
String appender = "Log4J Appender: ";
switch (type) {
case TOP_OF_MINUTE:
LogLog.debug(appender + name + " to be rolled every minute.");
break;
case TOP_OF_HOUR:
LogLog.debug(appender + name + " to be rolled on top of every hour.");
break;
case HALF_DAY:
LogLog.debug(appender + name + " to be rolled at midday and midnight.");
break;
case TOP_OF_DAY:
LogLog.debug(appender + name + " to be rolled at midnight.");
break;
case TOP_OF_WEEK:
LogLog.debug(appender + name + " to be rolled at start of week.");
break;
case TOP_OF_MONTH:
LogLog.debug(appender + name + " to be rolled at start of every month.");
break;
default:
LogLog.warn("Unknown periodicity for appender [" + name + "].");
}
}
private int computeCheckPeriod() {
RollingCalendar rollingCalendar = new RollingCalendar(gmtTimeZone, Locale.ENGLISH);
Date epoch = new Date(0);
if (datePattern != null) {
for (int i = TOP_OF_MINUTE; i <= TOP_OF_MONTH; i++) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(datePattern);
simpleDateFormat.setTimeZone(gmtTimeZone);
String r0 = simpleDateFormat.format(epoch);
rollingCalendar.setType(i);
Date next = new Date(rollingCalendar.getNextCheckMillis(epoch));
String r1 = simpleDateFormat.format(next);
if (!r0.equals(r1)) {
return i;
}
}
}
return TOP_OF_TROUBLE;
}
private void rollOver() throws IOException {
if (datePattern == null) {
errorHandler.error("Missing DatePattern option in rollOver().");
return;
}
String datedFilename = fileName + sdf.format(now);
if (scheduledFilename.equals(datedFilename)) {
return;
}
this.closeFile();
File target = new File(scheduledFilename);
if (target.exists()) {
Files.delete(target.toPath());
}
File file = new File(fileName);
boolean result = file.renameTo(target);
if (result) {
LogLog.debug(fileName + " -> " + scheduledFilename);
} else {
LogLog.error("Failed to rename [" + fileName + "] to [" + scheduledFilename + "].");
}
try {
this.setFile(fileName, false, this.bufferedIO, this.bufferSize);
} catch (IOException e) {
errorHandler.error("setFile(" + fileName + ", false) call failed.");
}
scheduledFilename = datedFilename;
}
#Override
protected void subAppend(LoggingEvent event) {
long n = System.currentTimeMillis();
if (n >= nextCheck) {
now.setTime(n);
nextCheck = rc.getNextCheckMillis(now);
try {
cleanupAndRollOver();
} catch (IOException ioe) {
LogLog.error("cleanupAndRollover() failed.", ioe);
}
}
super.subAppend(event);
}
public String getCompressBackups() {
return compressBackups;
}
public void setCompressBackups(String compressBackups) {
this.compressBackups = compressBackups;
}
public String getMaxNumberOfDays() {
return maxNumberOfDays;
}
public void setMaxNumberOfDays(String maxNumberOfDays) {
this.maxNumberOfDays = maxNumberOfDays;
}
protected void cleanupAndRollOver() throws IOException {
File file = new File(fileName);
Calendar cal = Calendar.getInstance();
int maxDays = 7;
try {
maxDays = Integer.parseInt(getMaxNumberOfDays());
} catch (Exception e) {
// just leave it at 7.
}
cal.add(Calendar.DATE, -maxDays);
Date cutoffDate = cal.getTime();
if (file.getParentFile().exists()) {
File[] files = file.getParentFile().listFiles(new StartsWithFileFilter(file.getName(), false));
int nameLength = file.getName().length();
for (File value : Optional.ofNullable(files).orElse(new File[0])) {
String datePart;
try {
datePart = value.getName().substring(nameLength);
Date date = sdf.parse(datePart);
if (date.before(cutoffDate)) {
Files.delete(value.toPath());
} else if (getCompressBackups().equalsIgnoreCase("YES") || getCompressBackups().equalsIgnoreCase("TRUE")) {
zipAndDelete(value);
}
} catch (Exception pe) {
// This isn't a file we should touch (it isn't named correctly)
}
}
}
rollOver();
}
private void zipAndDelete(File file) throws IOException {
if (!file.getName().endsWith(".zip")) {
File zipFile = new File(file.getParent(), file.getName() + ".zip");
try (FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(zipFile);
ZipOutputStream zos = new ZipOutputStream(fos)) {
ZipEntry zipEntry = new ZipEntry(file.getName());
zos.putNextEntry(zipEntry);
byte[] buffer = new byte[4096];
while (true) {
int bytesRead = fis.read(buffer);
if (bytesRead == -1) {
break;
} else {
zos.write(buffer, 0, bytesRead);
}
}
zos.closeEntry();
}
Files.delete(file.toPath());
}
}
class StartsWithFileFilter implements FileFilter {
private String startsWith;
private boolean inclDirs;
StartsWithFileFilter(String startsWith, boolean includeDirectories) {
super();
this.startsWith = startsWith.toUpperCase();
inclDirs = includeDirectories;
}
public boolean accept(File pathname) {
if (!inclDirs && pathname.isDirectory()) {
return false;
} else {
return pathname.getName().toUpperCase().startsWith(startsWith);
}
}
}
class RollingCalendar extends GregorianCalendar {
private static final long serialVersionUID = -3560331770601814177L;
int type = CustomLog4jAppender.TOP_OF_TROUBLE;
RollingCalendar() {
super();
}
RollingCalendar(TimeZone tz, Locale locale) {
super(tz, locale);
}
void setType(int type) {
this.type = type;
}
long getNextCheckMillis(Date now) {
return getNextCheckDate(now).getTime();
}
Date getNextCheckDate(Date now) {
this.setTime(now);
switch (type) {
case CustomLog4jAppender.TOP_OF_MINUTE:
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.MINUTE, 1);
break;
case CustomLog4jAppender.TOP_OF_HOUR:
this.set(Calendar.MINUTE, 0);
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.HOUR_OF_DAY, 1);
break;
case CustomLog4jAppender.HALF_DAY:
this.set(Calendar.MINUTE, 0);
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
int hour = get(Calendar.HOUR_OF_DAY);
if (hour < 12) {
this.set(Calendar.HOUR_OF_DAY, 12);
} else {
this.set(Calendar.HOUR_OF_DAY, 0);
this.add(Calendar.DAY_OF_MONTH, 1);
}
break;
case CustomLog4jAppender.TOP_OF_DAY:
this.set(Calendar.HOUR_OF_DAY, 0);
this.set(Calendar.MINUTE, 0);
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.DATE, 1);
break;
case CustomLog4jAppender.TOP_OF_WEEK:
this.set(Calendar.DAY_OF_WEEK, getFirstDayOfWeek());
this.set(Calendar.HOUR_OF_DAY, 0);
this.set(Calendar.MINUTE, 0);
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.WEEK_OF_YEAR, 1);
break;
case CustomLog4jAppender.TOP_OF_MONTH:
this.set(Calendar.DATE, 1);
this.set(Calendar.HOUR_OF_DAY, 0);
this.set(Calendar.MINUTE, 0);
this.set(Calendar.SECOND, 0);
this.set(Calendar.MILLISECOND, 0);
this.add(Calendar.MONTH, 1);
break;
default:
throw new IllegalStateException("Unknown periodicity type.");
}
return getTime();
}
}
}
And use this properties in your log4j config file:
log4j.appender.[appenderName]=com.example.package.CustomLog4jAppender
log4j.appender.[appenderName].File=/logs/app-daily.log
log4j.appender.[appenderName].Append=true
log4j.appender.[appenderName].encoding=UTF-8
log4j.appender.[appenderName].layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.[appenderName].layout.ConversionPattern=%-5.5p %d %C{1.} - %m%n
log4j.appender.[appenderName].DatePattern='.'yyyy-MM-dd
log4j.appender.[appenderName].MaxNumberOfDays=7
log4j.appender.[appenderName].CompressBackups=true