To whom it my concern. Anf for those who don't like to send their own data into clouds ;->
I'll operate influx and grafana locally in my private network.
And also triggered by a specific sensor problem with the need for an simple and robust (non-secure/pure http) influx client for my one of my Arduinos.
Find sample code on ArduinoUNO InfluxDB - Wokwi ESP32, STM32, Arduino Simulator
Due to lack of connectivity all Ethernet stuff is not used there and Client.println is replaced by Serial.println.
An improved example using an temperature and humidity sensor (DHT22)
You have to implement your own sensor readout, see String Data for example.
Due to Arduino Uno 's and Duemilanove's capacity it use http only. But that is OK in my local network.
Don't use this for critical data.
Find more advanced code later within the next weeks on my github repository.
Cu f41_ardu