Flux influxdb.cardinality fails: influxdb provider requires a host to be specified

[russorat]

The following query works just fine in cloud, but when trying this in a 2.0.6 instance running in docker, i get the following error:

failed to initialize execute state: influxdb provider requires a host to be specified

import "influxdata/influxdb"

influxdb.cardinality(bucket: "telegraf", start: -1h)

When i try to add the host information, it fails with the same error:

import "influxdata/influxdb"

influxdb.cardinality(bucket: "telegraf", start: -1h, host: "http://influxdb:8086", token: "mytoken", orgID: "f89a598ed3c38f35")

here is my docker compose file:

version: '3'
services:
  influxdb:
    image: influxdb:2.0.6
    volumes:
      # Mount for influxdb data directory and configuration
      - influxdbv2:/.influxdbv2
    ports:
      - "8086:8086"
  # Use the influx cli to set up an influxdb instance.
  influxdb_cli:
    links:
      - influxdb
    image: influxdb:2.0.6
    # Use these same configurations parameters in your telegraf configuration, mytelegraf.conf.
    entrypoint: influx setup --bucket telegraf -t mytoken -o InfluxData --username=russ --password=something --host=http://influxdb:8086 -f
    # Wait for the influxd service in the influxdb container has fully bootstrapped before trying to setup an influxdb instance with the influxdb_cli service.
    restart: on-failure:10
    depends_on:
      - influxdb
  telegraf:
    image: telegraf:latest
    links:
      - influxdb
    volumes:
      # Mount for telegraf config
      - ./telegraf.conf:/etc/telegraf/telegraf.conf:ro
    depends_on:
      - influxdb_cli
volumes:
  influxdbv2:

and here is my telegraf config:

[[inputs.internal]]

# Read metrics from one or many prometheus clients
[[inputs.prometheus]]
  name_override = "influxdb_oss"
  ## An array of urls to scrape metrics from.
  urls = ["http://influxdb:8086/metrics"]

  ## Metric version controls the mapping from Prometheus metrics into
  ## Telegraf metrics.  When using the prometheus_client output, use the same
  ## value in both plugins to ensure metrics are round-tripped without
  ## modification.
  ##
  ##   example: metric_version = 1;
  ##            metric_version = 2; recommended version
  metric_version = 2

  ## HTTP Basic Authentication username and password. ('bearer_token' and
  ## 'bearer_token_string' take priority)
  # username = ""
  # password = ""

  ## Specify timeout duration for slower prometheus clients (default is 3s)
  # response_timeout = "3s"

  ## Optional TLS Config
  # tls_ca = /path/to/cafile
  # tls_cert = /path/to/certfile
  # tls_key = /path/to/keyfile
  ## Use TLS but skip chain & host verification
  # insecure_skip_verify = false

# Output Configuration for telegraf agent
[[outputs.influxdb_v2]]
  ## Point to your influxdb container
 urls = ["http://influxdb:8086"]
  ## Token for authentication; created with the influxdb_cli service.
  token = "mytoken"
  ## Organization is the name of the organization you wish to write to; created with the influxdb_cli service.
  organization = "InfluxData"
  ## Destination bucket to write into; created with the influxdb_cli service.
  bucket = "telegraf"

[nylocx]

From the docs:
https://docs.influxdata.com/influxdb/v2.0/reference/flux/stdlib/influxdb/cardinality/

InfluxDB Cloud supports the influxdb.cardinality() function, but InfluxDB OSS does not.

So currently no way to get the cardinality in the OSS Version?

-- EDIT --
I found this on the web and it seems to work even if I do not fully understand it.

import "influxdata/influxdb"

from(bucket: "your-bucket")
  |> range(start: -3y)
  |> first()
  |> group()
  |> count()