puppetserver: Fix Cannot run program /bin/config-version.sh

Author: Krinkle

modules/profile/templates/puppet/server/default.erb

@@ -1,7 +1,13 @@
 JAVA_BIN="/usr/bin/java"
 
 # Modify this if you'd like to change the memory allocation, enable JMX, etc
-JAVA_ARGS="-Xms<%= @java_memory %> -Xmx<%= @java_memory %> -Djruby.logger.class=com.puppetlabs.jruby_utils.jruby.Slf4jLogger"
+#
+# * We use launchMechanism=vfork as of Marc 2025, because puppetserver suddenly became
+#   unable to execute the /bin/config-version.sh script without it.
+#   > Puppet Exception Cannot run program "/etc/puppet/code/environments/production/bin/config-version.sh" (in directory "."): error=0, Failed to exec spawn helper, exit value: 1.
+#   https://anton.dollmaier.name/2025/02/puppetserver-failed-to-exec-spawn-helper/
+#
+JAVA_ARGS="-Xms<%= @java_memory %> -Xmx<%= @java_memory %> -Djruby.logger.class=com.puppetlabs.jruby_utils.jruby.Slf4jLogger -Djdk.lang.Process.launchMechanism=vfork"
 
 # Modify this as you would JAVA_ARGS but for non-service related subcommands
 JAVA_ARGS_CLI="${JAVA_ARGS_CLI:-}"