HADOOP-8865. Log warning message when loading deprecated properties from resources

[zabetak]

Description of PR

The goal is to emit the warning message when deprecated properties are loaded from XML configuration files to inform users that obsolete properties are in use. Before this patch we only inform users when a set/get operation is performed on a deprecated property but this is not sufficient cause if the users/apps are using the new key to obtain the value they will never see the warning. As a result when the property is finally removed or stops taking effect the application will fail or showcase different behavior.

With this patch deprecated properties may be logged twice:

• when a deprecated prop is loaded from a resource
• when a deprecated prop is accessed via get/set; if the deprecated key is not accessed no additional log is generated

How was this patch tested?

mvn -pl hadoop-common-project/hadoop-common test -Dtest=TestConf*

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• [] Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• [] If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• [] If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[hadoop-yetus]

🎊 +1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	9m 48s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+0 🆗	detsecrets	0m 1s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ trunk Compile Tests _
+1 💚	mvninstall	24m 24s		trunk passed
+1 💚	compile	8m 36s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	compile	7m 32s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	checkstyle	0m 34s		trunk passed
+1 💚	mvnsite	0m 48s		trunk passed
+1 💚	javadoc	0m 42s		trunk passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 26s		trunk passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 26s		trunk passed
+1 💚	shadedclient	21m 51s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 34s		the patch passed
+1 💚	compile	8m 3s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javac	8m 3s		the patch passed
+1 💚	compile	7m 30s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	javac	7m 30s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
-0 ⚠️	checkstyle	0m 37s	/results-checkstyle-hadoop-common-project_hadoop-common.txt	hadoop-common-project/hadoop-common: The patch generated 4 new + 207 unchanged - 2 fixed = 211 total (was 209)
+1 💚	mvnsite	0m 57s		the patch passed
+1 💚	javadoc	0m 45s		the patch passed with JDK Ubuntu-11.0.27+6-post-Ubuntu-0ubuntu120.04
+1 💚	javadoc	0m 36s		the patch passed with JDK Private Build-1.8.0_452-8u452-gaus1-0ubuntu120.04-b09
+1 💚	spotbugs	1m 33s		the patch passed
+1 💚	shadedclient	22m 1s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	16m 46s		hadoop-common in the patch passed.
+1 💚	asflicense	0m 44s		The patch does not generate ASF License warnings.
		137m 28s

Subsystem	Report/Notes
Docker	ClientAPI=1.50 ServerAPI=1.50 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7737/1/artifact/out/Dockerfile
GITHUB PR	#7737
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux b5fe1c928b2a 5.15.0-136-generic #147-Ubuntu SMP Sat Mar 15 15:53:30 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
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Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7737/1/testReport/
Max. process+thread count	2152 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-common U: hadoop-common-project/hadoop-common
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-7737/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[slfan1989]

@zabetak Thanks for the contribution! @cnauroth Could you help review this PR? Thank you very much!

[cnauroth]

LGTM. Thank you @zabetak !

[cnauroth]

I committed this to trunk. @zabetak , thank you for the patch.

[zabetak]

Thanks for the review @cnauroth , much appreciated!

[cnauroth]

@zabetak and @slfan1989 , sorry, I think we may need to revert #7766 and #7737 . I noticed that all of the deprecation warnings are coming out in shell command output, which is unexpected and may break scripting. These are warnings for properties declared in core-default.xml, so they aren't easily within the user's control.

> bin/hadoop fs -ls gs://cnauroth-bucket
2025-08-29 21:08:04,116 INFO Configuration.deprecation: fs.default.name in core-default.xml is deprecated. Instead, use fs.defaultFS
2025-08-29 21:08:04,311 INFO Configuration.deprecation: fs.default.name in core-default.xml is deprecated. Instead, use fs.defaultFS
2025-08-29 21:08:04,397 INFO Configuration.deprecation: fs.default.name in core-default.xml is deprecated. Instead, use fs.defaultFS
2025-08-29 21:08:04,558 INFO Configuration.deprecation: fs.default.name in core-default.xml is deprecated. Instead, use fs.defaultFS
2025-08-29 21:08:04,724 INFO Configuration.deprecation: io.bytes.per.checksum in core-default.xml is deprecated. Instead, use dfs.bytes-per-checksum
2025-08-29 21:08:04,724 INFO Configuration.deprecation: fs.default.name in core-default.xml is deprecated. Instead, use fs.defaultFS
Found 80 items
...

[slfan1989]

@zabetak and @slfan1989 , sorry, I think we may need to revert #7766 and #7737 . I noticed that all of the deprecation warnings are coming out in shell command output, which is unexpected and may break scripting. These are warnings for properties declared in core-default.xml, so they aren't easily within the user's control.

@cnauroth Thank you for your feedback. I believe rolling back is a feasible option. @zabetak, we really appreciate your contributions, but it seems this has affected some functionality, and a rollback is necessary. If we find a better solution, we will assist with the review.

[zabetak]

@cnauroth @slfan1989 Thanks for the feedback. Not sure if we should keep discussing here or under a new JIRA ticket but here are few thoughts.

The fact that the built-in config files such as core-default.xml use deprecated properties seems problematic to me. I would argue that once a property is deprecated it shouldn't be used anywhere inside the project. If we agree on this then maybe we should invest some time to remove/replace existing usages of deprecated properties such as fs.default.name.

Moreover, the deprecation warnings can be disabled (or directed to another file) by end-users by changing the respective logging configuration. I am wondering if it is normal/expected to have all logs directed in the console for CLI utilities.