systemd

19
Aug
2021

How to automatically re-resolve DNS in Wireguard on Linux

When installing wireguard-tools on Linux, it includes a script called reresolve-dns.sh. This will take care of automatically re-resolving.

According to its documentation, you should run it every 30 seconds or so.

So we can just create a systemd timer to run it every 30 seconds.

Easy way

Use our script

wget -qO- https://techoverflow.net/scripts/install-wireguard-reresolve-dns.sh | sudo bash /dev/stdin

Now you need to enable it for each relevant interface separately, for example for wg0:

systemctl enable --now [email protected]

Hard way

Do manually what our script does.

Create /etc/systemd/system/[email protected]:

[Unit]
[email protected]

[Service]
Type=oneshot
ExecStart=/usr/share/doc/wireguard-tools/examples/reresolve-dns/reresolve-dns.sh %i

Create /etc/systemd/system/[email protected]:

[Unit]
[email protected] timer
[Timer]
[email protected]%i.service
OnCalendar=*-*-* *:*:00,30
Persistent=true
[Install]
WantedBy=timers.target

Now you need to enable it for each relevant interface separately, for example for wg0:

systemctl enable --now [email protected]
Posted by Uli Köhler in Networking, systemd, VPN, Wireguard
19
Aug
2021

How to run systemd timer every 30 seconds

The syntax to run a systemd timer every 30 seconds is:

OnCalendar=*-*-* *:*:00,30

i.e. run on the first (00) and 30th second of every minute.

Posted by Uli Köhler in Linux, systemd
19
Jun
2021

How to run Jupyter Hub (multi-user mode) using systemd

The following script will install Jupyter Hub in single user mode (i.e. only a single Linux user can login to Jupyter Hub using the web interface).

Prerequisites

First install Python & PIP, then NodeJS, then Jupyter Hub, then configurable-http-proxy :

curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
sudo apt-get install -y nodejs python3-pip
sudo pip3 install jupyterhub
sudo npm i -g configurable-http-proxy

Installing the Jupyter Hub systemd service

Run the following script using sudo!

#!/bin/bash
# This script installs and enables/starts the JupyterHub systemd service
export NAME=JupyterHub

# Create service file
cat >/etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=${NAME}

[Service]
Type=simple
ExecStart=/usr/bin/env jupyterhub --port=11569
User=root
Group=root

Restart=on-failure
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now ${NAME}

This script will install a systemd service named JupyterHub autostart it on boot. It is running on port 11569 by default.

Posted by Uli Köhler in Python, systemd
18
Jun
2021

How to run Jupyter Hub (single user mode) using systemd for autostart

Note: This will only allow a single (preconfigured) user to login to Jupyter lab! See How to run Jupyter Hub (multi-user mode) using systemd on how to deploy Jupyter Hub in multi-user mode using systemd, which allows any Unix user to login!

The following script will install Jupyter Hub in single user mode (i.e. only a single Linux user can login to Jupyter Hub using the web interface).

Prerequisites

First install Python & PIP, then NodeJS, then Jupyter Hub, then configurable-http-proxy :

curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
sudo apt-get install -y nodejs python3-pip
sudo pip3 install jupyterhub
sudo npm i -g configurable-http-proxy

Installing the Jupyter Hub systemd service

Run the following script as the user you want to be able to login! Do not run the script using sudo !

#!/bin/bash
# This script installs and enables/starts a systemd service
export NAME=JupyterHub-$USER
export GROUP=$(id -gn $USER)
# Create service file
sudo tee /etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=${NAME}

[Service]
Type=simple
ExecStart=/usr/bin/env jupyterhub

WorkingDirectory=$HOME
User=$USER
Group=$GROUP

Restart=on-failure
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now ${NAME}

This script will install a systemd service named JupyterHub-$USER (where $USER is the current user, e.g. uli) and autostart it on boot.

Running multiple services

If you run multiple services, you can run the script for each user and choose a unique port for each service by adding --port=7219 to the /usr/bin/env jupyter hub command, e.g.

ExecStart=/usr/bin/env jupyterhub --port=7192

Alternatively, you can run a single systemwide Jupyter Hub in multi-user mode where multiple users can log in.

Posted by Uli Köhler in Python, systemd
11
Jun
2021

How to run Jupyter Lab as systemd service

If you want to run your Jupyter Lab as a network service on any modern Linux distribution, you can install a systemd service that runs Jupyter. First, you need to install jupyter lab using

sudo pip3 install jupyterlab

In case you don’t have pip3, use sudo apt -y install python3-pip or the equivalent on your distribution.

Note that this script will run Jupyter without token authentication and without password and it will listen on any IP (--ip=0.0.0.0) by default. Either change the command line flags or be aware of the security implications !

#!/bin/bash
# This script installs and enables/starts a systemd service
export NAME=Jupyter

# Create service file
cat >/etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=${NAME}

[Service]
Type=simple
ExecStart=/usr/bin/env jupyter lab --ip=0.0.0.0 --port 17256 --LabApp.token=''

WorkingDirectory=/home/uli/jupyter
User=uli
Group=uli

Restart=on-failure
RestartSec=5s

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now ${NAME}

You need to change the following entries in the script in order to make it work for you:

WorkingDirectory=/home/uli/jupyter
User=uli
Group=uli

Set the WorkingDirectory to whatever directory you want Jupyter to run in. Note that anyone being able to access the webinterface will basically have full access to that directory!

Set User and Group to the user that should run. Note that running Jupyter as root is not allowed. In case you still want to do it, add the --allow-root flag to the command line options.

Now run the script as root to install the service:

sudo ./install-jupyter-service.sh

Now you can access Jupyter at http://[ip of the computer]:17256.

Changing the configuration

In order to change the configuration, I recommend to edit /etc/systemd/systemd/Jupyter.service (or /etc/systemd/systemd/${NAME}.service if you changed export NAME=Jupyter) directly. After that, run

sudo systemctl daemon-reload
sudo systemctl restart Jupyter

You can also change the installation script and re-run it, but you still need to run daemon-reload and restart.

Running multiple Jupyter instances

In order to run  multiple instances, just run multiple copies of the installation script with different names. For example, use

export NAME=Jupyter-DeepLearning

Debugging Jupyter Lab output

If you have problems with Juypter Lab starting up, use

sudo systemctl status Jupyter

in order to view the status and

sudo journalctl -xfu Jupyter

to view all the logs.

Status output example:

● Jupyter.service - Jupyter
     Loaded: loaded (/etc/systemd/system/Jupyter.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2021-06-11 03:44:28 CEST; 4s ago
   Main PID: 48753 (jupyter-lab)
      Tasks: 1 (limit: 14226)
     Memory: 51.7M
     CGroup: /system.slice/Jupyter.service
             └─48753 /usr/bin/python3 /usr/local/bin/jupyter-lab --ip=0.0.0.0 --port 17256 --LabApp.token=

Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.215 ServerApp] nbclassic | extension was successfully loaded.
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.216 LabApp] JupyterLab extension loaded from /usr/local/lib/python3.8/dist-packages/jupyterlab
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.216 LabApp] JupyterLab application directory is /usr/local/share/jupyter/lab
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.219 ServerApp] jupyterlab | extension was successfully loaded.
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.220 ServerApp] Serving notebooks from local directory: /dev/shm
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.220 ServerApp] Jupyter Server 1.8.0 is running at:
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.220 ServerApp] http://uli-desktop:17256/lab
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.220 ServerApp]     http://127.0.0.1:17256/lab
Jun 11 03:44:29 uli-desktop env[48753]: [I 2021-06-11 03:44:29.220 ServerApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
Jun 11 03:44:29 uli-desktop env[48753]: [W 2021-06-11 03:44:29.224 ServerApp] No web browser found: could not locate runnable browser.

Uninstalling the Jupyter Lab service

In order to just stop and disable autostart (but not uninstall) the jupyter lab service, use

sudo systemctl disable --now Jupyter

After that, you can just remove the service file in order to permanently uninstall the service:

sudo rm /etc/systemd/system/Jupyter.service

You can always reinstall using our installation script.

Note that if you have changed the export NAME=... line, you need to replace Jupyter by the value of Name

Posted by Uli Köhler in Python, systemd
11
Jun
2021

Autoinstall script for systemd timer and associated service

The following script will install a systemd .timer file and the associated .service file  into /etc/systemd/system/ and enable the timer (i.e. start on boot) and start the timer immediately.

#!/bin/bash
# This script installs and enables/starts a systemd timer
# It also installs the service file that is run by the given timer
export NAME=MyService

cat >/etc/systemd/system/${NAME}.service <<EOF
# ADD SYSTEMD SERVICE FILE CONTENT HERE
EOF

cat >/etc/systemd/system/${NAME}.timer <<EOF
# ADD SYSTEMD TIMER FILE CONTENT HERE
EOF

# Enable and start service
systemctl enable --now ${NAME}.timer

In order to modify the script for your systemd service, replace MyService by the desired name of your service in

export NAME=MyService

insert the content of your .service file at

# ADD SYSTEMD SERVICE FILE CONTENT HERE

and insert the content of your .timer file at

# ADD SYSTEMD TIMER FILE CONTENT HERE

Full example

The following complete example installs a systemd service named MyService that runs /usr/bin/python3 myscript.py every two hours:

#!/bin/bash
# This script installs and enables/starts a systemd timer
# It also installs the service file that is run by the given timer
export NAME=MyService

cat >/etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=${NAME}

[Service]
Type=oneshot
ExecStart=/usr/bin/python3 myscript.py
WorkingDirectory=/opt/myservice
EOF

cat >/etc/systemd/system/${NAME}.timer <<EOF
[Unit]
Description=${NAME} timer

[Timer]
OnCalendar=*-*-* 00,02,04,06,08,10,12,14,16,18,20,22:00:00
Persistent=true

[Install]
WantedBy=timers.target
EOF

# Enable and start service
systemctl enable --now ${NAME}.timer
Posted by Uli Köhler in systemd
11
Jun
2021

How to run systemd timer every five minutes

The syntax to run a systemd timer every minute is:

OnCalendar=*-*-* *:00,05,10,15,20,25,30,35,40,45,50,55:00

i.e. run it on the first second (:00) of every 5th minute (00,05,10,15,20,25,30,35,40,45,50,55).

Posted by Uli Köhler in systemd
11
Jun
2021

How to run systemd timer every three hours

The syntax to run a systemd timer every three hours is:

OnCalendar=*-*-* 00,03,06,09,12,15,18,21:00:00

i.e. run it on the first minute and first second (00:00) of every second hour (00,03,06,09,12,15,18,21).

Posted by Uli Köhler in systemd
11
Jun
2021

How to run systemd timer every two hours

The syntax to run a systemd timer every two hours is:

OnCalendar=*-*-* 00,02,04,06,08,10,12,14,16,18,20,22:00:00

i.e. run it on the first minute and first second (00:00) of every second hour (00,02,04,06,08,10,12,14,16,18,20,22).

Posted by Uli Köhler in systemd
11
Jun
2021

How to run systemd timer every minute

The syntax to run a systemd timer every minute is:

OnCalendar=*-*-* *:*:00

i.e. run it on the first second (00) every minute.

Posted by Uli Köhler in systemd
11
Jun
2021

Autoinstall script for systemd service

The following script will install a systemd service file into /etc/systemd/system/ and enable it (i.e. start on boot) and start it immediately.

#!/bin/bash
# This script installs and enables/starts a systemd service
export NAME=MyService

# Create service file
cat >/etc/systemd/system/${NAME}.service <<EOF
# ADD SYSTEMD SERVICE FILE CONTENT HERE
EOF

# Enable and start service
systemctl enable --now ${NAME}

In order to modify the script for your systemd service, replace MyService by the desired name of your service in

export NAME=MyService

and insert the content of your .service file at

# ADD SYSTEMD SERVICE FILE CONTENT HERE

Full example

The following complete example installs a systemd service named MyService that runs /usr/bin/python3 myscript.py:

#!/bin/bash
# This script installs and enables/starts a systemd service
export NAME=MyService

# Create service file
cat >/etc/systemd/system/${NAME}.service <<EOF
[Unit]
Description=MyService

[Service]
Type=oneshot
ExecStart=/usr/bin/python3 myscript.py
WorkingDirectory=/opt/myservice

[Install]
WantedBy=multi-user.target
EOF

# Enable and start service
systemctl enable --now ${NAME}

 

Posted by Uli Köhler in systemd