JDownloader configuration for DSM7

This document helps with the setup of a startup script for running JDownloader on Synology with DSM7

Intro

DSM7 uses systemd for services statup operations. Systemd allows additional scripts and complex chaining of these. While systemd can be irksume manytimes, it's quite powerful and it is better to use it. This ensures any future update of DSM7 won't break your script and the startup.

Prerequisites

This page will help you to configure your Synology to automatically start, restart, stop and reload your JDownloader. Although, it requires you the following:

• You need admin rights on your Synology
• Your Synology must be connected to internet
• You need a basic understand of how a terminal works
• You need already to have JDownloader installed on your Synology
• You need to be able to connect from your computer to the Synology using SSH (if on Windows, check Putty)

Usage

Setting up Java JRE/JDK locally

You can skip this section if you already have Java installed or you prefer to follow another documented method.

Any JRE/JDK can work. I personally use Azul Zulu which is based on OpenJDK

Login to your Synology using SSH and download the Java Runtime Environment with the following command

curl https://cdn.azul.com/zulu/bin/zulu21.32.17-ca-jre21.0.2-linux_x64.tar.gz -o azul.tgz

Now, uncompress the JDK into /usr/local as following

sudo tar -xzf azul.tgz -C /usr/local

If you wish, you can confirm the operation with the following command

sudo ls -ltd /usr/local/*

You should see a directory as zulu21.32.17-ca-jre21.0.2-linux_x64 I would suggest you to link the JRE as following:

sudo ln -sf /usr/local/zulu21.32.17-ca-jre21.0.2-linux_x64 /usr/local/java

You cna further confirm the operation with the following:

stefano@synology:~$ sudo ls -lt  /usr/local/
total 44
lrwxrwxrwx  1 root root   35 Feb 16 09:59 java -> zulu21.32.17-ca-jre21.0.2-linux_x64
drwxr-xr-x  6 root root 4096 Jan  9 19:42 zulu21.32.17-ca-jre21.0.2-linux_x64

Install the script

It's now time to install the script. Connect again to your Synology using SSH and run

sudo curl https://raw.githubusercontent.com/LunaticMuch/synology-jdownloader/develop/pkg-jdownloader.service \
-o /usr/local/lib/systemd/system/pkg-jdownloader.service

You should see the following:

sudo ls -l /usr/local/lib/systemd/system/pkg-jdownloader.service

-rw-r--r-- 1 root root  345 Jun 15 09:41 pkg-jdownloader.service

Test the script

Run the following:

sudo systemctl start pkg-jdownloader.service

This will run the script. Now you can check modules in the kernel with systemctl as

root@synology:/volume1/@appstore/JDownloader# systemctl status pkg-jdownloader.service -l
● pkg-jdownloader.service - JDownloader
   Loaded: loaded (/usr/local/lib/systemd/system/pkg-jdownloader.service; disabled; vendor preset: disabled)
   Active: active (running) since Wed 2022-06-15 09:43:40 BST; 7min ago
  Process: 16984 ExecStart=/volume1/@appstore/JDownloader/start.sh (code=exited, status=0/SUCCESS)
 Main PID: 16986 (java)
   Memory: 144.7M
   CGroup: /system.slice/pkg-jdownloader.service
           └─16986 java -jar JDownloader.jar

This means JDownloader is actually running

Enable the script

The script must run at startup, so you need to tell systemd to do it

systemctl enable pkg-jdownloader.service

If you now reboot, this script will run before docker and the container will find the old ACM tty.

Startup script (Source)

[Unit]
Description=JDownloader
After=syslog.target network.target

[Service]
SuccessExitStatus=143
Type=forking

WorkingDirectory=/volume1/@appstore/JDownloader
ExecStart=/volume1/@appstore/JDownloader/start.sh
TimeoutStartSec=3600
TimeoutStopSec=3600
RemainAfterExit=true
PIDFile=/volume1/@appstore/JDownloader/JDownloader.pid


[Install]
WantedBy=multi-user.target

Limits

The script can accep additional parameters but it's not so flexible right not. ExecStart is required to run a bash script with the full path because this is the requirement of systemd. I plan to improve it, but for now it's fine and it's actually a script that you create and forget because it works.

Frequently Asked Question

I made a change to the script file, but now it does not work anymore

If you change the script file, you need to reload systemd as following

sudo systemctl daemon-reload

How can I monitor what the service is doing?

You have few options here. The first is to run

sudo systemctl status pkg-jdownloader.service -l

This will return you the service status and the last few lines logged by the service. The log won't be complete. If you need something that allow you to keep an eye on the service, you can use the journalctl command as following

journalctl -fu pkg-jdownloader.service

This will remain in tail until you issue a CTRL-C

Disclaimer

USE THIS AT YOUR RISK