[jira] [Created] (LOG4J2-3621) Log4J 2.19 breaks contract of order of loading of System Properties

["Adwait Kumar Singh (Jira)" <ji...@apache.org>]

Adwait Kumar Singh created LOG4J2-3621:
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             Summary: Log4J 2.19 breaks contract of order of loading of System Properties
                 Key: LOG4J2-3621
                 URL: https://issues.apache.org/jira/browse/LOG4J2-3621
             Project: Log4j 2
          Issue Type: Bug
          Components: Configuration
    Affects Versions: 2.19.0, 2.19.1
            Reporter: Adwait Kumar Singh


[This change|https://github.com/apache/logging-log4j2/pull/742] broke one of our systems on upgrading to 2.19.

In our applications we had both LOG4J_CONFIGURATION_FILE environment variable as well as log4j.configurationFile system property set.

In version 2.17.2 "log4j.configurationFile" gets priority vs in 2.19 "LOG4J_CONFIGURATION_FILE" gets priority. This also breaks the contract mentioned in the [documentation|https://logging.apache.org/log4j/2.x/manual/configuration.html#SystemProperties].

This is happening because of the normalization code here, [https://github.com/apache/logging-log4j2/blob/release-2.x/log4j-api/src/main/java/org/apache/logging/log4j/util/PropertiesUtil.java#L503-L526]

 

When we are trying to normalize, we are checking if the source contains the normalKey. In case both log4j.configurationFile and LOG4J_CONFIGURATION_FILE are present, the following sequence happens,
 # log4j.configurationFile does not get inserted into the normalized map because the normal key is log4j2.configurationFile which is not present in the SystemPropertiesSource.
 # Then when we hit the EnvironmentPropertiesSource, log4j.configurationFile is normalized to LOG4J_CONFIGURATION_FILE and then an entry is made in the normalized map with key = log4j.configurationFile, but value of LOG4J_CONFIGURATION_FILE.
 # During look up with first look into normalized map, so now we got the wrong value (EnvironmentVariable instead of SystemProperty).

 

I can think of two ways to fix this,
 # We make an entry into the normalized map with the actual key if the normalized key is not present in the source.
 # While fetching we prefer literal map over normalized map.


Would like to know which of the approaches would be better, can raise a PR accordingly.



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