[env:d1_mini]
build_flags = 
    -D WIFI_SSID=\"wifi ssid\"
    -D WIFI_PASS=\"wifi password\"
    -D MQTT_SERVER=\"mqtt broker address\"
    -D MQTT_PORT=mqtt port number
    -D MQTT_USER=\"mqttuser\"
    -D MQTT_PASS=\"mqttpass\"
    -D CA_CERT=\"-----BEGIN CERTIFICATE-----\nYOUR_CERT_HERE\n-----END CERTIFICATE-----\n\"