run entrypoint.sh directly as the entrypoint script, run the entrypoint.sh in debug mode -x, make entrypoint.sh executable +x, run java as non-elevated user

Dockerfile

@@ -18,4 +18,4 @@ VOLUME      /var/lib/mindustry/.mindustry
 
 COPY        ./entrypoint.sh /entrypoint.sh
 
-CMD         ["/bin/bash", "/entrypoint.sh"]
+ENTRYPOINT  /entrypoint.sh

entrypoint.sh

@@ -1,6 +1,6 @@
-#!/bin/bash
+#!/bin/bash -x
 # change ownership of home directory
 chown mindustry:mindustry -R ~mindustry
 
 # run server as non-elevated user
-su mindustry java -jar -Xms1G -Xmx2G Mindustry-server-4.0-alpha-56.jar host
+su mindustry bash -c 'java -jar -Xms1G -Xmx2G Mindustry-server-4.0-alpha-56.jar host'