[
https://issues.apache.org/jira/browse/KNOX-3246?focusedWorklogId=1002434&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-1002434
]
ASF GitHub Bot logged work on KNOX-3246:
----------------------------------------
Author: ASF GitHub Bot
Created on: 29/Jan/26 10:43
Start Date: 29/Jan/26 10:43
Worklog Time Spent: 10m
Work Description: smolnar82 opened a new pull request, #1141:
URL: https://github.com/apache/knox/pull/1141
[KNOX-3246](https://issues.apache.org/jira/browse/KNOX-3246) - Make Java
discovery deterministic on hosts with multiple JDKs
## What changes were proposed in this pull request?
Extend JAVA_VERSION_PATTERNS to include modern JDK layouts and
/usr/java/default. Follow symlinks during discovery and sort candidates to
ensure deterministic Java selection on hosts with multiple JDKs installed.
## How was this patch tested?
Tested on my cluster with mixed JDK versions.
```
$ cat smolnar_test.sh
#!/usr/bin/env bash
. /$KNOX_HOME/bin/knox-functions.sh
setVerbose "$@"
checkJava
```
Prior to my changes:
```
$ ./smolnar_test.sh --verbose
Found Java at /usr/java/jdk1.11.70.15-z.0_lu/bin/java
```
My changes included:
```
$ ./smolnar_test.sh --verbose
Found Java at /usr/java/default/bin/java
$ /usr/java/default/bin/java -version
openjdk version "17.0.11" 2024-04-16
OpenJDK Runtime Environment OpenLogic-OpenJDK (build
17.0.11+9-adhoc.root.jdk17u)
OpenJDK 64-Bit Server VM OpenLogic-OpenJDK (build
17.0.11+9-adhoc.root.jdk17u, mixed mode, sharing)
```
## Integration Tests
This issue is hard to reproduce in the existing docker-based framework. It
requires a multi JDK setup which usually happens at cluster upgrade time.
## UI changes
None
Issue Time Tracking
-------------------
Worklog Id: (was: 1002434)
Remaining Estimate: 0h
Time Spent: 10m
> Make Java discovery deterministic on hosts with multiple JDKs
> -------------------------------------------------------------
>
> Key: KNOX-3246
> URL: https://issues.apache.org/jira/browse/KNOX-3246
> Project: Apache Knox
> Issue Type: Improvement
> Components: Startup Scripts
> Affects Versions: 2.1.0, 3.0.0
> Reporter: Sandor Molnar
> Assignee: Sandor Molnar
> Priority: Critical
> Fix For: 3.0.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> h3. *Problem*
> Knox Java discovery is non-deterministic on hosts with multiple JDK
> installations.
> In environments where both Java 11 and Java 17 are installed, neither version
> is matched by the current {{{}JAVA_VERSION_PATTERNS{}}}. As a result, Java
> detection falls back to the generic {{/bin/java$}} pattern and selects the
> first match returned by {{{}find{}}}.
> Because the order of results from {{find}} is not guaranteed, different hosts
> in the same cluster may select different Java versions, leading to
> inconsistent and unpredictable behavior.
> ----
> h3. *Root Cause*
> * {{JAVA_VERSION_PATTERNS}} does not include patterns for Java 11 or Java 17
> installations.
> * {{{}/usr/java/default/bin/java{}}}, commonly used to define the
> system-preferred Java, is not recognized.
> * {{find}} is executed without {{{}-L{}}}, so symlinks are not followed.
> * The fallback selection uses {{head -n 1}} without stabilizing the result
> order.
> ----
> h3. *Example*
> On different hosts in the same cluster:
> /usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java
> /usr/java/jdk1.11.70.15-z.0_lu/bin/java
>
> or
> /usr/java/jdk1.11.70.15-z.0_lu/bin/java
> /usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java
>
> Depending on the host, Knox may start with Java 11 or Java 17.
> ----
> h3. *Proposed Fix*
> * Extend {{JAVA_VERSION_PATTERNS}} to explicitly recognize Java 11 and Java
> 17 layouts.
> * Add support for {{/usr/java/default/bin/java}} to honor the system default
> Java.
> * Use {{find -L}} to follow symlinks.
> * Sort Java candidates before selecting the first match to ensure
> deterministic behavior.
> ----
> h3. *Impact*
> Ensures consistent Java version selection across all nodes in a cluster,
> prevents unpredictable startup behavior, and aligns Knox Java discovery with
> common enterprise JDK layouts.
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