launch jenkins agent w/o jnlp, just via TCP

jenkins-node.service

[Unit]
Description=Jenkins Node

[Service]
ExecStart=/var/lib/jenkins/launch-tcp.sh
User=jenkins

launch-tcp.sh

#!/usr/bin/env bash

# launch agent w/o jnlp, just via TCP
# https://github.com/jenkinsci/remoting/blob/5a08bc5e5e/docs/inbound-agent.md#connect-directly-to-tcp-port
# -- ciis0, Apr 09, 2020

cd $(dirname $0)

# hudson.remoting.Base64.encode(org.jenkinsci.main.modules.instance_identity.InstanceIdentity.get().getPublic().getEncoded())
instance_id=

secret=
agent=

master=ci.example.com:50000

java -cp agent.jar hudson.remoting.jnlp.Main \
  -headless \
  -noreconnect \
  -workDir $HOME/jenkins \
  -direct $master \
  -protocols JNLP4-connect \
  -instanceIdentity @<(cat <<<$instance_id) \
  @<(cat <<<$secret) $agent