Espruino did unexpectedly have a module to talk to InfluxDB directly: https://github.com/espruino/EspruinoDocs/blob/master/modules/InfluxDB.js. Given that it's a simple HTTP POST request (see previous blog entry), I should not have been surprised.

That simplifies data ingestion: no need for MQTT broker, no need for an MQTT-to-InfluxDB converter. The InfluxDB instance is on the local network this way since SSL is still not doable on an ESP8266.

This is the Espruino code:

// InfluxDB configuration
 var influxDBParams = {
    influxDBHost: "192.168.1.14",
    influxPort: 8086,
    influxDBName: "demo",
    influxUserName: "submit",  
    influxPassword: "submitpw",
    influxAgentName: "ESP32"
   };

var influxDB = require("InfluxDB").setup(influxDBParams);

// bme() is the function to read from the BME280 sensor
let temperature=bme.readTemperature()

let data="env "+temperature+"="+temperature;
influxDB.write(data);

That's it. As simple as MQTT.