Logstash error - ERROR StatusLogger No log4j2 configuration file found

I always check logstash configuration file using command line before running logstash service.

After up gradation to Logstash 5, I encountered this error.

ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
Sending Logstash's logs to /var/log/logstash which is now configured via log4j2.properties
2017-01-18 14:29:52,358 main ERROR FileManager (/var/log/logstash/logstash-plain.log) java.io.FileNotFoundException: /var/log/logstash/logstash-plain.log (Permission denied) java.io.FileNotFoundException: /var/log/logstash/logstash-plain.log (Permission denied)
        at java.io.FileOutputStream.open0(Native Method)
        at java.io.FileOutputStream.open(FileOutputStream.java:270)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:133)
        at org.apache.logging.log4j.core.appender.rolling.RollingFileManager$RollingFileManagerFactory.createManager(RollingFileManager.java:430)
        at org.apache.logging.log4j.core.appender.rolling.RollingFileManager$RollingFileManagerFactory.createManager(RollingFileManager.java:403)
        at org.apache.logging.log4j.core.appender.AbstractManager.getManager(AbstractManager.java:73)
        at org.apache.logging.log4j.core.appender.OutputStreamManager.getManager(OutputStreamManager.java:81)
        at org.apache.logging.log4j.core.appender.rolling.RollingFileManager.getFileManager(RollingFileManager.java:103)
        at org.apache.logging.log4j.core.appender.RollingFileAppender.createAppender(RollingFileAppender.java:191)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
 
There were couple of mistakes.
1) I was running logstash on command line as a root. It is required to run it as "logstash" user.
2) I was not giving absolute path for --path.settings and -f options. An interesting discussion thread can be followed here - https://discuss.elastic.co/t/logstash-5-not-running/64449/47

So, if you wish to run logstash(ver 5.x) on command line, you should do this:

Test logstash configurations using command line
----------------------------------------------
[psj@desk joshi]# sudo -u logstash /usr/share/logstash/bin/logstash --path.settings /etc/logstash -f /etc/logstash/conf.d/redis-logstash.conf --config.test_and_exit --verbose


Run logstash on command line and not as a service
-----------------------------------------------------------------------------------
[psj@desk joshi]# sudo -u logstash /usr/share/logstash/bin/logstash --path.settings /etc/logstash -f /etc/logstash/conf.d/redis-logstash.conf

Important notes:

1) Make sure that the options that you give for path.settings and configuration file are absolute.
2) Don't add "/" at the end of directory setting for path.settings (i.e. - /etc/logstash)
3) Keep track of the generated logs under /var/log/logstash/logstash-plain.log

You can change the logging level in log4j2 configuration file by setting status to "info" instead of "error" and you will get to know what is the problem!

 [psj@desk joshi]#head /etc/logstash/log4j2.properties
status = info
name = LogstashPropertiesConfig

Now run logstash on command line - e.g.:

[psj@desk joshi]# sudo -u logstash /usr/share/logstash/bin/logstash --path.settings /etc/logstash -f /etc/logstash/conf.d/redis-logstash.conf