[HBASE-24309] Avoid introducing log4j and slf4j-log4j dependencies for modules other than hbase-assembly - ASF JIRA

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Type: Sub-task
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: None
Fix Version/s: 3.0.0-alpha-1, 2.3.0
Component/s: logging, pom
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Add a hbase-logging module, put the log4j related code in this module only so other modules do not need to depend on log4j at compile scope. See the comments of Log4jUtils and InternalLog4jUtils for more details.

Add a log4j.properties to the test jar of hbase-logging module, so for other sub modules we just need to depend on the test jar of hbase-logging module at test scope to output the log to console, without placing a log4j.properties in the test resources as they all (almost) have the same content. And this test module will not be included in the assembly tarball so it will not mess up the binary distribution.

Ban direct commons-logging dependency, and ban commons-logging and log4j imports in non-test code, to avoid mess up the downstream users logging framework. In hbase-logging module we do need to use log4j classes and the trick is to use full class name.

Add jcl-over-slf4j and jul-to-slf4j dependencies, as some of our dependencies use jcl or jul as logging framework, we should also redirect their log message to slf4j.

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Add a hbase-logging module, put the log4j related code in this module only so other modules do not need to depend on log4j at compile scope. See the comments of Log4jUtils and InternalLog4jUtils for more details. Add a log4j.properties to the test jar of hbase-logging module, so for other sub modules we just need to depend on the test jar of hbase-logging module at test scope to output the log to console, without placing a log4j.properties in the test resources as they all (almost) have the same content. And this test module will not be included in the assembly tarball so it will not mess up the binary distribution. Ban direct commons-logging dependency, and ban commons-logging and log4j imports in non-test code, to avoid mess up the downstream users logging framework. In hbase-logging module we do need to use log4j classes and the trick is to use full class name. Add jcl-over-slf4j and jul-to-slf4j dependencies, as some of our dependencies use jcl or jul as logging framework, we should also redirect their log message to slf4j.

Description

In general, a library should not force the down stream users to use a specific logging framework, and this is why there is a slf4j library.

For HBase, since we also publish the testing-util module which almost depends on all other sub modules, we should not introduce logging dependencies other than slf4j-api in these modules. We should only add log4j dependencies in hbase-assembly and ship it with our binary distribution.

This is also important for switching to log4j2.