Do any one knows how to add a empty line in slf4j logs without its formatting.
To get empty log I have added empty string as log.
log.error("");
I need to get it with out formatting, Just empty line, Please help.
In your logback.xml, declare a "minimal" appender that doesn't embellish the log message with timestamps or log levels or anything like so:
<appender name="minimal" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%m%n</pattern>
</encoder>
</appender>
Then declare a logger that uses that appender like so:
<logger name="blank.line.logger" level="ALL" additivity="false">
<appender-ref ref="minimal"/>
</logger>
In your Java code where you'd like to produce empty log lines, you'll need a reference to that logger separate from whatever other logger you're using for regular log messages, something like
private static final Logger blankLineLogger = LoggerFactory.getLogger("blank.line.logger");
Then you can get your desired blank line in the log output with
blankLineLogger.info("");
The accepted answser is a bit tricky, for me I just use a simple log.error("\n") , or append a \n in the previous log line.
Related
I want to print the event severity in sentence case, in the logs instead of default Uppercase. I have modified the log4j2 xml like below,
<Console name="STDOUT" target="SYSTEM_OUT" direct=true>
<PatternLayout pattern="%level{WARN=Warning, DEBUG=Debug, ERROR=Error, TRACE=Trace, INFO=Info}"/>
</Console>
<Loggers>
<AsyncRoot level="INFO" includeLocation="false">
<AppenderRef ref="STDOUT">
</AsyncRoot>
</Loggers>
Current Event Severity Printed in Logs :
INFO / WARNING / DEBUG / ERROR / TRACE
Expected Event Severity Printed in Logs :
Info/ Warning / Debug / Error / Trace
I still see the event is getting printed in Uppercase in logs. Something else need to be changed ?
According to my reading of the org.apache.logging.log4j.core.pattern.LevelPatternConverter source code, Log4j2 should output the level replacement strings exactly as you gave them in the pattern.
If that's not happening, check that Log4j2 is actually using that config.
If that doesn't resolve the problem, you may need to use a debugger to figure out what is going on.
This is a Java question.
I have around 100 static functions that use a slf4j logger.
I want to add some metadata to standardise the logs - assume it's some kind of preamble that is a function of what processing is currently going on.
How can I get the logger to print that metadata without going in to each of the static functions and changing them to explicitly add in the metadata.
e.g.
static Logger logger; ...
void mainProcessing() {
String file = "current_file.txt";
int line = 3;
...
func1();
func2();
...
}
void func1() {
...
logger.warn("some warning");
}
I'd like to see "WARN: File current_file.txt, line 3, msg: some warning" in the logs.
Any ideas?
(Prefer not to have to change each of the func1() functions obviously, if possible)
Thanks in advance.
You need to specify print format. However beware, that obtaining line number and/or file will greatly decrease your application performance. This is not C++, Logback will probably create a Throwable object for each line, to retrieve the stacktrace and extract the line number and file name.
Regarding line:
L / line Outputs the line number from where the logging request was
issued.
Generating the line number information is not particularly fast. Thus,
its use should be avoided unless execution speed is not an issue.
Regarding file:
F / file Outputs the file name of the Java source file where the
logging request was issued.
Generating the file information is not particularly fast. Thus, its
use should be avoided unless execution speed is not an issue.
http://logback.qos.ch/manual/layouts.html#file
Sample logback.xml configuration would be:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
<encoder>
<pattern>%d{"yy-MM-dd HH:mm:ss,SSS"}: %-5p %F:%L [%t] %c{0}: %M - %m%n</pattern>
</encoder>
</appender>
<root level="INFO">
<appender-ref ref="console" />
</root>
</configuration>
Better to redesign your code, that messages are more verbose and not unique, containing the context and required data to debug it by a person that does not know the code very well (your future co-worker)
I have an appender in my logback xml config:
<encoder>
<pattern>%d{"yyyy-MM-dd HH:mm:ss"} [%thread] %-5level %logger{5} - %msg %n</pattern>
</encoder>
but it prints out the abbreviated package along with the class, even if I set it to %logger{1} like:
2019-12-19 10:26:16 [main] INFO o.f.d.d.u.Myclass - my message
I want it to just log the class MyClass like log4j does. How?
looks like the number you specify for %logger is some kind of special case and doesnt' exactly dictate size. Except it does dictate size, but never less than a minimum size which is the entire package path with the full class name. Unless you set it to "0" which is a special case to mean "don't include the package".
So if I set it to %logger{0} then I get just the class name, see http://logback.qos.ch/manual/layouts.html#conversionWord
2019-12-19 10:28:45 [main] INFO MyClass - my message
In log4j the equivalent would have been %c{1} or %logger{1} so I guess it's different.
This question already has answers here:
Logging for application in different environment Log4j
(2 answers)
Closed 5 years ago.
I have a log4j.xml config file. I want to change log level if environmental variables changes. I have multiple environmental which are DEVELOP, TEST, PREPROD etc. How can I do this?
DEVELOP:
<Loggers>
<Root level="debug">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
TEST:
<Loggers>
<Root level="error">
<AppenderRef ref="Console"/>
</Root>
</Loggers>
I would say create several appenders, one for each setting and with its own log level. Then decide at runtime which one to get, and fetch the logger accordingly.
For example:
log4j.rootLogger=WARN
log4j.com.yourcompany.package1= DEBUG, appender1, stdout
log4j.com.yourcompany.package2= INFO, appender2, stdout
Then define appender1 and 2 in the file. You can enter the same output file to the two appenders. When creating the logger in Java, you can choose between the two:
final Logger log = Logger.getLogger(package1.Class1.class);
// final Logger log = Logger.getLogger(package2.Class2.class);
I didn't test it, but I think it works. I believe you can also use class names instead of package names in log4j.xml definitions.
I came into the same situation and I did below,
Have separate log4j configurations with the suffix as the environment.
log4j-<ENVIRONMENT>.xml
In your logger factory class or in the minus d options pass the environment and pick the correct file,
String log4jFile = "/log4j-" + System.getProperty("ENVIRONMENT") + ".xml";
String url = LoggerFactory.class.getResource(log4jFile);
org.apache.log4j.xml.DOMConfigurator.configure(url);
Is it possible some how to use MDC to name the log file at run time.
I have a single web application which is being called by different names at the same time using tomcat docbase. So i need to have separate log files for each of them.
This can be accomplished in Logback, the successor to Log4J.
Logback is intended as a successor to the popular log4j project, picking up where log4j leaves off.
See the documentation for Sifting Appender
The SiftingAppender is unique in its capacity to reference and configure nested appenders. In the above example, within the SiftingAppender there will be nested FileAppender instances, each instance identified by the value associated with the "userid" MDC key. Whenever the "userid" MDC key is assigned a new value, a new FileAppender instance will be built from scratch. The SiftingAppender keeps track of the appenders it creates. Appenders unused for 30 minutes will be automatically closed and discarded.
In the example, they generate a separate log file for each user based on an MDC value.
Other MDC values could be used depending on your needs.
This is also possible with log4j. You can do this by implementing your own appender. I guess the easiest way is to
subclass AppenderSkeleton.
All logging events end up in the append(LoggingEvent event) method you have to implement.
In that method you can access the MDC by event.getMDC("nameOfTheKeyToLookFor");
Then you could use this information to open the file to write to.
It may be helpful to have a look at the implementation of the standard appenders like RollingFileAppender to figure out the rest.
I used this approach myself in an application to separate the logs of different threads into different log files and it worked very well.
I struggled for a while to find SiftingAppender-like functionality in log4j (we couldn't switch to logback because of some dependencies), and ended up with a programmatic solution that works pretty well, using an MDC and appending loggers at runtime:
// this can be any thread-specific string
String processID = request.getProcessID();
Logger logger = Logger.getRootLogger();
// append a new file logger if no logger exists for this tag
if(logger.getAppender(processID) == null){
try{
String pattern = "%d{yy/MM/dd HH:mm:ss} %p %c{2}: %m%n";
String logfile = "log/"+processID+".log";
FileAppender fileAppender = new FileAppender(
new PatternLayout(pattern), logfile, true);
fileAppender.setName(processID);
// add a filter so we can ignore any logs from other threads
fileAppender.addFilter(new ProcessIDFilter(processID));
logger.addAppender(fileAppender);
}catch(Exception e){
throw new RuntimeException(e);
}
}
// tag all child threads with this process-id so we can separate out log output
MDC.put("process-id", processID);
//whatever you want to do in the thread
LOG.info("This message will only end up in "+processID+".log!");
MDC.remove("process-id");
The filter appended above just checks for a specific process id:
public class RunIdFilter extends Filter {
private final String runId;
public RunIdFilter(String runId) {
this.runId = runId;
}
#Override
public int decide(LoggingEvent event) {
Object mdc = event.getMDC("run-id");
if (runId.equals(mdc)) {
return Filter.ACCEPT;
}
return Filter.DENY;
}
}
Hope this helps a bit.
As of 20-01-2020, this is now a default functionality of Log4j.
To achieve that you just need to use a RoutingAppender with MDC.
Example:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Appenders>
<Routing name="Analytics" ignoreExceptions="false">
<Routes>
<Script name="RoutingInit" language="JavaScript"><![CDATA[
// This script must return a route name
//
// Example from https://logging.apache.org/log4j/2.x/manual/appenders.html#RoutingAppender
// on how to get a MDC value
// logEvent.getContextMap().get("event_type");
//
// but as we use only one route with dynamic name, we return 1
1
]]>
</Script>
<Route>
<RollingFile
name="analytics-${ctx:event_type}"
fileName="logs/analytics/${ctx:event_type}.jsonl"
filePattern="logs/analytics/$${date:yyyy-MM}/analytics-${ctx:event_type}-%d{yyyy-dd-MM-}-%i.jsonl.gz">
<PatternLayout>
<pattern>%m%n</pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy/>
<SizeBasedTriggeringPolicy size="250 MB"/>
</Policies>
</RollingFile>
</Route>
</Routes>
<!-- Created appender TTL -->
<IdlePurgePolicy timeToLive="15" timeUnit="minutes"/>
</Routing>
</Appenders>
<Loggers>
<Logger name="net.bytle.api.http.AnalyticsLogger" level="debug" additivity="false">
<AppenderRef ref="Analytics"/>
</Logger>
</Loggers>
</Configuration>
To known more, see Log4j - How to route message to log file created dynamically.