Backport "HBASE-27814 Add support for dump and process metrics servlet in REST InfoServer" to branch-2.6

[NihalJain]

Other changes:

• Ensure info server stops during stop()
• Extract header and footer. This would fix the log level page layout for rest web UI (See HBASE-20693)
• Add hostname in the landing page instead of just port similar to other web UIs

[NihalJain]

Backports #5215. Sorry for the mess-up in previous PR.

FYI @ndimiduk@bbeaudreault

[NihalJain]

Built code locally, extracted assembly, started a local cluster and started HBase REST server.

1. Verified the landing page has the right page title, all the tabs are visible, hostname is displayed instead of portnumber and no error in page rendering.
2. Verified /logLevel page is fixed with appropriate tabs, as expected and shown in HBASE-20693
3. Verified newly added http://localhost:9093/processRest.jsp works as expected
4. Verified newly added http://localhost:9093/dump page works as expected
5. Verified all other pages like /logs, /jmx, /conf works as before
6. Ran postman collection for basic CRUD test for REST at https://gist.github.com/NihalJain/7db91823bd140e41953a88eb3df56eae: All tests PASS

• 

[Apache-HBase]

🎊 +1 overall

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		_ Prechecks _
		_ branch-2.6 Compile Tests _
+1 💚	mvninstall	3m 2s	branch-2.6 passed
+1 💚	compile	0m 17s	branch-2.6 passed
+1 💚	shadedjars	5m 44s	branch has no errors when building our shaded downstream artifacts.
+1 💚	javadoc	0m 16s	branch-2.6 passed
		_ Patch Compile Tests _
+1 💚	mvninstall	2m 48s	the patch passed
+1 💚	compile	0m 17s	the patch passed
+1 💚	javac	0m 17s	the patch passed
+1 💚	shadedjars	5m 40s	patch has no errors when building our shaded downstream artifacts.
+1 💚	javadoc	0m 14s	the patch passed
		_ Other Tests _
+1 💚	unit	3m 39s	hbase-rest in the patch passed.
		24m 4s

Subsystem	Report/Notes
Docker	ClientAPI=1.43 ServerAPI=1.43 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-5729/1/artifact/yetus-jdk11-hadoop3-check/output/Dockerfile
GITHUB PR	#5729
Optional Tests	javac javadoc unit shadedjars compile
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versions	git=2.34.1 maven=3.8.6
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[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	1m 1s	Docker mode activated.
-0 ⚠️	yetus	0m 6s	Unprocessed flag(s): --brief-report-file --spotbugs-strict-precheck --whitespace-eol-ignore-list --whitespace-tabs-ignore-list --quick-hadoopcheck
		_ Prechecks _
		_ branch-2.6 Compile Tests _
+1 💚	mvninstall	2m 50s	branch-2.6 passed
+1 💚	compile	0m 20s	branch-2.6 passed
+1 💚	shadedjars	5m 2s	branch has no errors when building our shaded downstream artifacts.
+1 💚	javadoc	0m 19s	branch-2.6 passed
		_ Patch Compile Tests _
+1 💚	mvninstall	3m 25s	the patch passed
+1 💚	compile	0m 22s	the patch passed
+1 💚	javac	0m 22s	the patch passed
+1 💚	shadedjars	6m 7s	patch has no errors when building our shaded downstream artifacts.
+1 💚	javadoc	0m 16s	the patch passed
		_ Other Tests _
+1 💚	unit	5m 1s	hbase-rest in the patch passed.
		26m 1s

Subsystem	Report/Notes
Docker	ClientAPI=1.44 ServerAPI=1.44 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-5729/1/artifact/yetus-jdk8-hadoop2-check/output/Dockerfile
GITHUB PR	#5729
Optional Tests	javac javadoc unit shadedjars compile
uname	Linux c010f1fccae8 5.4.0-169-generic #187-Ubuntu SMP Thu Nov 23 14:52:28 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
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git revision	branch-2.6 / c8eb184
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modules	C: hbase-rest U: hbase-rest
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versions	git=2.34.1 maven=3.8.6
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[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	0m 38s	Docker mode activated.
		_ Prechecks _
+1 💚	dupname	0m 0s	No case conflicting files found.
+1 💚	hbaseanti	0m 0s	Patch does not have any anti-patterns.
+1 💚	@author	0m 0s	The patch does not contain any @author tags.
		_ branch-2.6 Compile Tests _
+1 💚	mvninstall	3m 52s	branch-2.6 passed
+1 💚	compile	0m 33s	branch-2.6 passed
+1 💚	checkstyle	0m 12s	branch-2.6 passed
+1 💚	spotless	0m 55s	branch has no errors when running spotless:check.
+1 💚	spotbugs	0m 39s	branch-2.6 passed
		_ Patch Compile Tests _
+1 💚	mvninstall	3m 39s	the patch passed
+1 💚	compile	0m 35s	the patch passed
-0 ⚠️	javac	0m 35s	hbase-rest generated 2 new + 164 unchanged - 2 fixed = 166 total (was 166)
+1 💚	checkstyle	0m 12s	the patch passed
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+1 💚	hadoopcheck	12m 31s	Patch does not cause any errors with Hadoop 2.10.2 or 3.3.6.
+1 💚	spotless	0m 51s	patch has no errors when running spotless:check.
+1 💚	spotbugs	0m 52s	the patch passed
		_ Other Tests _
+1 💚	asflicense	0m 11s	The patch does not generate ASF License warnings.
		27m 34s

Subsystem	Report/Notes
Docker	ClientAPI=1.44 ServerAPI=1.44 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-5729/1/artifact/yetus-general-check/output/Dockerfile
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Optional Tests	dupname asflicense javac spotbugs hadoopcheck hbaseanti spotless checkstyle compile
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[NihalJain]

Hey @ndimiduk could you please review this. This is exact same change as #5215 which you had earlier reviewed.

[ndimiduk]

Ran postman collection for basic CRUD test for REST at https://gist.github.com/NihalJain/7db91823bd140e41953a88eb3df56eae: All tests PASS

Do we not have this kind of basic functional test in the suite?

[ndimiduk]

LGTM

FYI, I don't usually request review of backport PRs, unless there's something particularly tricky/different between the master and backport changes. In this case, the diffs look basically identical (by my scan), so I would just make the PR to verify the build-bot is happy and move on.

[NihalJain]

Do we not have this kind of basic functional test in the suite?

I suppose we do but that must run inside minicluster. I run this by pointing to a node (local/distributed).

FYI, I don't usually request review of backport PRs, unless there's something particularly tricky/different between the master and backport changes.

Ah seems I am being extra cautious. Let me follow this approach going forward.

the diffs look basically identical

They are exactly same here.

Thanks for you review. I will merge this then.