fluentd cannot log into influxdb as admin

[winnall]

First of all, apologies in advance because I am new to Fluentd, InfluxDB and Grafana, and I don't have a lot of experience with Docker either.

I'm trying to make fluentd-influxdb-grafana work as downloaded from here. Everything seems to start up OK and I can log into influxdb-1 and grafana-1 via their web interfaces without problem.

On starting the container fluentd-1 I get the following messages in its log. The problem seems to be that the user admin is not created for the container influxdb-1. Also, I'm not sure what the relationship of the file /fluentd/etc/fluent.conf is to the mount /FLUENTD/ETC/FLUENT.CONF, which points at a file on my real disk that contains something different.

I have tried creating the user admin and the database test in influxdb-1, but without success: influxdb-1 only lets me create a simple user when it is initialised, and calling that user admin does not help at all.

fluent:x:1000:1000::/home/fluent:
2022-09-14 13:38:56 +0000 [info]: parsing config file is succeeded path="/fluentd/etc/fluent.conf"
2022-09-14 13:38:57 +0000 [info]: using configuration file: <ROOT>
  <source>
    @type tail
    path "/var/log/logs.json"
    pos_file "/fluentd/logs.json.pos"
    tag "default.logs"
    format json
    <parse>
      @type json
    </parse>
  </source>
  <match default.logs>
deluser: can't find fluent in /etc/group
    @type influxdb
    host "influxdb"
    port 8086
    dbname "test"
    user "admin"
    password xxxxxx
    use_ssl false
    time_precision "ms"
    <buffer>
      @type "memory"
      flush_interval 5
    </buffer>
  </match>
</ROOT>
2022-09-14 13:38:57 +0000 [info]: starting fluentd-1.3.2 pid=8 ruby="2.5.2"
2022-09-14 13:38:57 +0000 [info]: spawn command to main:  cmdline=["/usr/bin/ruby", "-Eascii-8bit:ascii-8bit", "/usr/bin/fluentd", "-c", "/fluentd/etc/fluent.conf", "-p", "/fluentd/plugins", "--under-supervisor"]
2022-09-14 13:38:58 +0000 [info]: gem 'fluent-plugin-influxdb' version '2.0.0'
2022-09-14 13:38:58 +0000 [info]: gem 'fluentd' version '1.3.2'
2022-09-14 13:38:58 +0000 [info]: adding match pattern="default.logs" type="influxdb"
2022-09-14 13:38:58 +0000 [info]: adding source type="tail"
2022-09-14 13:38:58 +0000 [info]: #0 starting fluentd worker pid=38 ppid=8 worker=0
2022-09-14 13:38:58 +0000 [info]: #0 Connecting to database: test, host: influxdb, port: 8086, username: admin, use_ssl = false, verify_ssl = true

2022-09-14 13:38:58 +0000 [info]: #0 skip database presence check because 'admin' user doesn't have admin privilege. Check 'test' exists on influxdb

2022-09-14 13:38:58 +0000 [info]: #0 following tail of /var/log/logs.json
2022-09-14 13:38:58 +0000 [info]: #0 fluentd worker is now running worker=0