ddnsdaemon

A simple python script that gathers data from the clients on which it is installed for monitoring purposes

Crontab

install the daemon (short procedure)

• clone the project git clone https://github.com/takamaka-dev/ddnsdaemon.git
• enter the project directory cd ddnsaemon
• setup the virtual env python3.9 -m venv /home/ddns/ddnsdaemon/6FeetUnder
• activate the env
• install the required packages:
  • pip install wheel
  • pip install netifaces psutil
  • pip install requests flask_restful http configparser waitress
• Call python main.py The first call will fail by creating stubs of the configuration files
• update the *.properties files with the correct settings
• Call python main.py to run the server in foregroud

run service-like

Assuming to you have downloaded the daemon in the following path /home/ddns/ddnsdaemon and the virtual env with name 6FeetUnder inside the daemon folder

crontab -e

The call with execution every 5 minutes:

*/5 * * * * cd /home/ddns/ddnsdaemon && screen -d -m /home/ddns/ddnsdaemon/6FeetUnder/bin/python main.py

call update

The ddnsdaemon must be called periodically to collect data from the machine on which it is installed. This is a simple example of a timed call that takes advantage of the crontab daemon.

I create a file with the curl call to the update route.

#!/bin/bash
curl -X GET 'http://localhost:13131/cronjob'

Assuming to have created the file with name call.sh in the path /home/ddns/call.sh I proceed to assign it the execution permissions:

chmod 755 /home/ddns/call.sh

To finish I set the crontab call with the command:

crontab -e

The call with execution every minute:

* * * * * /home/ddns/call.sh

Install the daemon step-by-step

requirements

To be able to use this procedure, it is necessary to have a system-wide installation:

• the crond daemon
• the screen package

screen

yum install screen

python

sudo dnf install python3.9

Git

sudo dnf install git

crond

sudo dnf update
sudo dnf install crontabs

crond FEDORA

dnf install cronie cronie-anacron

verify cron

sudo systemctl start crond.service
sudo systemctl enable crond.service

Test installed daemon:

sudo systemctl status crond.service

result

● crond.service - Command Scheduler
     Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
     Active: active (running) since Thu 2021-09-02 17:17:58 CEST; 6 days ago
   Main PID: 1623299 (crond)
      Tasks: 1 (limit: 38304)
     Memory: 2.1M
        CPU: 4min 53.520s
     CGroup: /system.slice/crond.service
             └─1623299 /usr/sbin/crond -n

set 09 12:01:01 my-server CROND[2177336]: (root) CMDEND (run-parts /etc/cron.hourly)
set 09 13:01:01 my-server CROND[2180537]: (root) CMD (run-parts /etc/cron.hourly)
set 09 13:01:01 my-server CROND[2180535]: (root) CMDEND (run-parts /etc/cron.hourly)
set 09 14:01:01 my-server CROND[2183754]: (root) CMD (run-parts /etc/cron.hourly)
set 09 14:01:01 my-server CROND[2183752]: (root) CMDEND (run-parts /etc/cron.hourly)
set 09 15:01:01 my-server CROND[2186925]: (root) CMD (run-parts /etc/cron.hourly)
set 09 15:01:01 my-server CROND[2186923]: (root) CMDEND (run-parts /etc/cron.hourly)
set 09 16:01:01 my-server CROND[2200738]: (root) CMD (run-parts /etc/cron.hourly)
set 09 16:01:01 my-server CROND[2200736]: (root) CMDEND (run-parts /etc/cron.hourly)
set 09 16:48:01 my-server crond[1623299]: (ddns) RELOAD (/var/spool/cron/ddns)

login as root

After connecting to the server with the root user, create a user with standard permissions.

adduser ddns
su ddns

Using the newly created ddns user

From the user's home, clone the latest version of the ddns daemon.

# go to home
cd
# clone the last version of the software
git clone https://github.com/takamaka-dev/ddnsdaemon.git
# go to ddnsdaemon
cd ddnsdaemon
# create virtualenv
python3.9 -m venv /home/ddns/ddnsdaemon/6FeetUnder
# enable virtualenv
source 6FeetUnder/bin/activate
# upgrade pip
pip install --upgrade pip
# install the required dependencies
pip install wheel
pip install flask_restful requests configparser waitress 
pip install netifaces psutil

daemon setup

Edit the daemon config file:

nano /home/ddns/ddnsdaemon/config.properties

To save CTRL + X and than Y

test the daemon startup

# enter the project folder
cd /home/ddns/ddnsdaemon
# load the virtualenv
source 6FeetUnder/bin/activate
# run the daemon
python main.py

If all dependencies are met, the server will start in debug mode.

Pid File is /tmp/ddnsdaemon.pid file exists: True
PID: 2201431
Pid file value is: 2201431
Server is not running with expected configuration HTTPConnectionPool(host='localhost', port=13131): Max retries exceeded with url: /watchdog (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7fbcb9a71880>: Failed to establish a new connection: [Errno 111] Connection refused'))
pid exists and running False
expired pid file successfully deleted
My pid is 2201504
I'm launcher running on: Linux
APPDATA: None
PID: 7
Mode True
lion_67
debug
 * Serving Flask app 'main' (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on all addresses.
   WARNING: This is a development server. Do not use it in a production deployment.
 * Running on http://192.168.0.194:13131/ (Press CTRL+C to quit)

first daemon call

We now make the first call to the daemon and if everything is correctly configured, we get the following response from `curl.

request

curl -X GET http://localhost:13131/cronjob

response

{"result": "record updated", "request": "update-machine-registration"}

switch to production mode

We stop the daemon with CTRL + C in the shell where it was launched.

We edit the config.properties file to switch from the test server to the production server.

nano /home/ddns/ddnsdaemon/config.properties

Edit the debug line in the [app] section as follows

old value

[app]
debug = True

new value

[app]
debug = False

To save CTRL + X and than Y

the "daemon" part

We configure crontab to restart the server in the event of a malfunction or reboot.

It is also possible to create a service for systemctl but it is beyond the scope of this guide and would only apply to distros that use this service boot mode.

Assuming to you have downloaded the daemon in the following path /home/ddns/ddnsdaemon and the virtual env with name 6FeetUnder inside the daemon folder

crontab -e

The call with execution every 5 minutes:

*/5 * * * * cd /home/ddns/ddnsdaemon && screen -d -m /home/ddns/ddnsdaemon/6FeetUnder/bin/python main.py

the "update" part

nano /home/ddns/call.sh

We insert the following command in the file.

#!/bin/bash
curl -X GET 'http://localhost:13131/cronjob'

To save CTRL + X and than Y

The ddns daemon must be called periodically to collect data from the machine on which it is installed. This is a simple example of a timed call that takes advantage of the crontab daemon.

Assuming to have created the file with name call.sh in the path /home/ddns/call.sh I proceed to assign it the execution permissions:

chmod 755 /home/ddns/call.sh

To finish I set the crontab call with the command:

crontab -e

The call with execution every minute:

* * * * * /home/ddns/call.sh

verify the crontab

Crontab log

cat /var/log/cron

verify if the daemon server is running

Login as ddns

screen -ls

result

There is a screen on:
        2203249..my-server  (Detached)
1 Socket in /run/screen/S-ddns.