fix(docker): use absolute path to run s3mock.jar

Also copy to "/opt/" instead of the root directory.

Fixes #2827

Author: afranken

CHANGELOG.md

@@ -117,7 +117,7 @@ Whenever a 3rd party library is updated, S3Mock will update it's MINOR version.
 # PLANNED - 6.x - RELEASE TBD
 Version 6.x is JDK25 LTS bytecode compatible, with Docker integration.
 
-Probably released with Spring Boot 5.x, updating baselines etc. as Spring Boot 5.x requires.
+Will be released after Spring Boot 5.x, updating baselines etc. as Spring Boot 5.x requires.
 
 Any JUnit / direct Java usage support will most likely be dropped and only supported on a best-effort basis.
 (i.e., the modules will be deleted from the code base and not released anymore. It *may* be possible to
@@ -150,6 +150,7 @@ Version 5.x is JDK17 LTS bytecode compatible, with Docker and JUnit / direct Jav
 
 * Features and fixes
   * Get object with range now returns the same headers as non-range calls.
+  * Docker: Copy "s3mock.jar" to "/opt/", run with absolute path reference to avoid issues when working directory is changed. (fixes #2827)
 * Refactorings
   * Use Jackson 3 annotations and mappers.
   * AWS has deprecated SDK for Java v1 and will remove support EOY 2025.

docker/Dockerfile

@@ -59,7 +59,7 @@ ENV JAVA_HOME=/opt/java-minimal
 ENV PATH="$PATH:$JAVA_HOME/bin"
 
 COPY --from=staging_area "$JAVA_HOME" "$JAVA_HOME"
-COPY ./target/s3mock-exec.jar s3mock.jar
+COPY ./target/s3mock-exec.jar /opt/s3mock.jar
 
 ENV LANG=en_US.UTF-8
 ENV LANGUAGE=en_US:en
@@ -69,4 +69,4 @@ ENV root=/s3mockroot
 EXPOSE 9090 9191
 
 # run the app on startup
-ENTRYPOINT ["java", "--illegal-access=warn", "-Djava.security.egd=file:/dev/./urandom", "-XX:+UseZGC", "-XX:+ZGenerational", "-jar", "s3mock.jar" ]
+ENTRYPOINT ["java", "--illegal-access=warn", "-Djava.security.egd=file:/dev/./urandom", "-XX:+UseZGC", "-XX:+ZGenerational", "-jar", "/opt/s3mock.jar" ]