CODEWITHSUNDEEP
java-8log4j
starFire
starFire

Reputation: 117

Log4j: Setting the generated log filename to include hostname

I am trying to generate logs using log4j. Logging part is working correctly, but I want to include the hostname (where the logs are generated) to be appended in the filename.

for eg: my current logfile name: logger.2019-06-12-06-14

what i want: logger_$HOST.2019-06-12-06-14 , where $HOST is the hostname

I have already seen other posts in stackoverflow and depending on that I have set the hostname in my Java code where I think its getting set before calling log4j

    static {
        try {
            HOST_NAME = InetAddress.getLocalHost().getCanonicalHostName();
        } catch (UnknownHostException e) {
            HOST_NAME = "localhost";
        }
        System.setProperty("hostname", HOST_NAME);
    }

and have modified the cfg file (where we have properties defined for all the loggers), to include the system property:

    *.*.log4j.appender.MyLogger.File=/logs/logger_$hostname;

But the resultant filename generated is logger_$hostname.2019-06-12-06-14 (which is literally $hostname instead of the property value)

In the posts, it does mention that the way to assign the variable in the cfg file is logger_${hostname} but while compiling it throws err with unexpected {, so I just put $hostname instead.

I have tried other ways too, like putting 

    *.*.log4j.appender.MyLogger.File=/logs/logger_$env:hostname;

    *.*.log4j.appender.MyLogger.File=$hostname;

    *.*.log4j.appender.MyLogger.File=/logs/logger_$HOST;
 (thinking since its running in unix, it might pick the HOST variable :( )

but no luck so far. Any ideas what I might be doing wrong?

BTW, I am calling the logger by this:

    private static Logger logger = Logger.getLogger("MyLogger");

So, is it possible to set the hostname from the class where I am logging. I do want to rotate my logs every minute, so dont want to mess with other log4j settings. My complete log4j appender properties:

    *.*.log4j.logger.myLogger=(INFO,MyLogger);
    *.*.log4j.additivity.myLogger=false; # this logger does not show up in main logs
    *.*.log4j.appender.MyLogger.File=/logs/logger_$hostname;
    *.*.log4j.appender.MyLogger.layout=org.apache.log4j.PatternLayout;
    # %n: new line for each entry
    *.*.log4j.appender.MyLogger.layout.ConversionPattern="%m%n";
    *.*.log4j.appender.MyLogger.Append=true;
    *.*.log4j.appender.MyLogger.ImmediateFlush=true;
    *.*.log4j.appender.MyLogger.Encoding=UTF8;

    # Enable 1 minute rotation
    *.*.log4j.appender.MyLogger.DatePattern="'.'yyyy-MM-dd-HH-mm";
    # Disable periodic flush since files will be flushed upon rotation that happens every minute
    *.*.log4j.appender.MyLogger.PeriodicFlush=false;

Any ideas to fix it will be very helpful. (And apologies since its kind of a repetitive question but I am not able to figure out the issue with the earlier posts :( )

Upvotes: 0

Views: 3100

Answers (2)

user167313
user167313

Reputation: 39

I have replaced ${hostname} by ${hostName} and it worked. <RollingFile name="LogToFile" fileName="${env:LOG_ROOT}/${env:LOG_RELEASE}/myFile.${hostName}.json" in log4j2.xml

Upvotes: 0

Nico
Nico

Reputation: 928

You can use the ${env:HOST} option in the log4j2.xml for environment lookup as mentioned in the documentation: https://logging.apache.org/log4j/2.0/manual/lookups.html#EnvironmentLookup

For example: 

<RollingRandomAccessFile name="CustomLoggerRandomFile"
                             fileName="logs/${env:HOST}_system.log"
                             filePattern="${env:HOST}_system-%d{yyyy-MM-dd}-%i.log.gz"
                             immediateFlush="false">

EDIT: I assumed that you are using log4j2 and the $HOST variable must be created in the host machine (where the logs are generated) as an environment variable.

Upvotes: 1

Related Questions