[Bug]: Sending SIGHUP to a TrapperKeeper app before startup has finished will kill it

[Sharpie]

Is this a critical security issue?

• This is not a security issue.

Describe the Bug

TrapperKeeper applications, that is OpenVox Server and OpenVoxDB, go through a startup phase that is mostly driven from the run function in core.clj:

https://github.com/OpenVoxProject/trapperkeeper/blob/5.0.5/src/puppetlabs/trapperkeeper/core.clj#L151-L169

The first function call, boot-with-cli-data, blocks until the application has finished its start cycle. This can take several seconds, during which run is blocked. Once the start cycle is finished, internal/register-sighup-handler is executed to set up SIGHUP handling.

This order of operations means that while start is executing, the JVM default SIGHUP handler is in place and the process will exit if it receives a reload signal:

The JVM catches signals to implement shutdown hooks for unexpected termination. The JVM uses SIGHUP, SIGINT, and SIGTERM to initiate the running of shutdown hooks.
https://docs.oracle.com/en/java/javase/21/docs/specs/man/java.html#extra-options-for-java

Expected Behavior

Sending a reload signal to a TrapperKeeper process undergoing startup should not cause it to suddenly blink out of existence. The signal should either be ignored, or buffered and used to trigger a reload after start finishes.

Steps to Reproduce

1. Obtain a RedHat 10 VM

2. Install OpenVox Server:

dnf install -y https://yum.voxpupuli.org/openvox9-release-el-10.noarch.rpm
dnf install -y openvox-server-9.0.0~beta5

3. Use the following test script to start the puppetserver service and send it an early SIGHUP:

#!/bin/bash

printf '%s\n' 'Stopping service...'
systemctl stop puppetserver

touch /tmp/test-start-time

printf '%s\n' 'Watching logs...'
journalctl -f _SYSTEMD_UNIT=puppetserver.service + SYSLOG_IDENTIFIER=puppetserver &
log_watch_pid=$?

systemctl start --no-block puppetserver.service

while [ /tmp/test-start-time -nt /var/run/puppetlabs/puppetserver/puppetserver.pid ]; do
  sleep 1
done

pid=$(cat /var/run/puppetlabs/puppetserver/puppetserver.pid)

kill -HUP $pid
while kill -0 $pid &>/dev/null; do
  sleep 1
done

kill -HUP $log_watch_pid
wait

Environment

Version 8.x, 9.x
Platform ANY

Additional Context

No response

Relevant log output

# ./test-hup.sh
Stopping service...
Watching logs...
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,207 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFileNamingAndTriggeringPolicy@4e36bceb - The date pattern is 'yyyy-MM-dd' from file name pattern '/var/log/puppetlabs/puppetserver/puppetserver-access-%d{yyyy-MM-dd}.%i.log.gz'.
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,207 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFileNamingAndTriggeringPolicy@4e36bceb - Roll-over at midnight.
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,207 |-INFO in ch.qos.logback.core.rolling.SizeAndTimeBasedFileNamingAndTriggeringPolicy@4e36bceb - Setting initial period to 2026-08-20T22:02:34.126Z
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,208 |-INFO in ch.qos.logback.core.model.processor.ImplicitModelHandler - Assuming default type [ch.qos.logback.access.common.PatternLayoutEncoder] for [encoder] property
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - Active log file name: /var/log/puppetlabs/puppetserver/puppetserver-access.log
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - Setting currentFileLength to 783375 for /var/log/puppetlabs/puppetserver/puppetserver-access.log
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - File property is set to [/var/log/puppetlabs/puppetserver/puppetserver-access.log]
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.core.model.processor.AppenderRefModelHandler - Attaching appender named [FILE] to default
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.core.model.processor.DefaultProcessor@77f07a48 - End of configuration.
Aug 21 20:53:03 rocky-10-tst puppetserver[16545]: 20:53:03,218 |-INFO in ch.qos.logback.access.common.joran.JoranConfigurator@344227ba - Registering current configuration as safe fallback point

Aug 21 20:53:08 rocky-10-tst puppetserver[16695]: Background process 16755 exited before start had completed

Hangup