[
https://issues.apache.org/jira/browse/KNOX-3246?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sandor Molnar updated KNOX-3246:
--------------------------------
Description:
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$}} pattern and selects the
first match returned by {{{}find{}}}.
Because the order of results from {{find}} is not guaranteed, different hosts
in the same cluster may select different Java versions, leading to inconsistent
and unpredictable behavior.
----
h3. *Root Cause*
* {{JAVA_VERSION_PATTERNS}} does not include patterns for Java 11 or Java 17
installations.
* {{{}/usr/java/default/bin/java{}}}, commonly used to define the
system-preferred Java, is not recognized.
* {{find}} is executed without {{{}-L{}}}, so symlinks are not followed.
* The fallback selection uses {{head -n 1}} without stabilizing the result
order.
----
h3. *Example*
On different hosts in the same cluster:
{code:java}
/usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java
/usr/java/jdk1.11.70.15-z.0_lu/bin/java{code}
or
{code:java}
/usr/java/jdk1.11.70.15-z.0_lu/bin/java
/usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java{code}
Depending on the host, Knox may start with Java 11 or Java 17.
----
h3. *Proposed Fix*
* Extend {{JAVA_VERSION_PATTERNS}} to explicitly recognize Java 11 and Java 17
layouts.
* Add support for {{/usr/java/default/bin/java}} to honor the system default
Java.
* Use {{find -L}} to follow symlinks.
* Sort Java candidates before selecting the first match to ensure
deterministic behavior.
----
h3. *Impact*
Ensures consistent Java version selection across all nodes in a cluster,
prevents unpredictable startup behavior, and aligns Knox Java discovery with
common enterprise JDK layouts.
was:
h3. *Problem*
Knox Java discovery is non-deterministic on hosts with multiple JDK
installations.
In environments where both Java 11 and Java 17 are installed, neither version
is matched by the current {{{}JAVA_VERSION_PATTERNS{}}}. As a result, Java
detection falls back to the generic {{/bin/java$}} 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.
> 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:
> {code:java}
> /usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java
> /usr/java/jdk1.11.70.15-z.0_lu/bin/java{code}
>
> or
> {code:java}
> /usr/java/jdk1.11.70.15-z.0_lu/bin/java
> /usr/lib/jvm/jdk1.17.0.11.0-openjdk/bin/java{code}
>
> 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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