Restore the GraalVM image variants (#4205)

build/ol/install-packages.sh

@@ -66,16 +66,12 @@ fi
 # Clean up DNF when done
 dnf clean all
 
-cat <<EOF > /usr/local/sbin/knockd
-#!/bin/sh
-
-echo "Auto-pause (using knockd) is currently unavailable on graalvm image variants"
-echo "Consider using a different image variant https://docker-minecraft-server.readthedocs.io/en/latest/versions/java/"
-echo "or mc-router's auto scale up/down feature https://github.com/itzg/mc-router#docker-auto-scale-updown"
-exit 2
-EOF
-chmod 755 /usr/local/sbin/knockd
-# TODO restore retrieval from https://github.com/Metalcape/knock when tar's "Cannot open: Invalid argument" is solved
+# Download and install patched knockd
+curl -fsSL -o /tmp/knock.tar.gz https://github.com/Metalcape/knock/releases/download/0.8.1/knock-0.8.1-$TARGET.tar.gz
+tar -xf /tmp/knock.tar.gz -C /usr/local/ && rm /tmp/knock.tar.gz
+ln -s /usr/local/sbin/knockd /usr/sbin/knockd
+ls -l /usr/local/sbin/knockd
+setcap cap_net_raw=ep /usr/local/sbin/knockd
 
 # Set git credentials globally
 cat <<EOF >> /etc/gitconfig

build/ol/setup-user.sh

@@ -1,2 +1,6 @@
+#!/bin/sh
+
+set -e
+
 groupadd --gid 1000 minecraft
 useradd --system --shell /bin/false --uid 1000 -g minecraft --home /data minecraft