Connection refused if the [client] part is not configured when setting up a multi-target configuration with [client.<name>] parts

[ArtDev45]

Description

Hi there, I'm using this exporter in Kubernetes cluster to get MySQL/MariaDB metrics from databases. I have several databases, so in config.my-cnf file I configured several targets and named them, e.g.:

[client.host1]
host=somehost1.local
[client.host2]
host=somehost2.local
[client.host3]
host=somehost3.local

I see metrics from targets, everything working good. But, I noticed next in the logs:

ts=2024-05-05T22:16:20.639Z caller=exporter.go:152 level=error msg="Error pinging mysqld" err="dial tcp 127.0.0.1:3306: connect: connection refused"

It looks like mysqld-exporter tries to connect to the localhost MariaDB. But, I didn't specify localhost values anywhere.
My suggestion is, if I don't configure [client] part, then exporter get default values and tries to connect to the localhost.

So, the questions are: Is it possible to configure targets with name ([client.host1]) instead of [client]? Maybe have you already fixed this issue in newer versions? Or, is exporter has special argument to disable default client?

Host operating system: output of uname -a

It's docker container, the output of uname -a command:

Linux mysql-exporter-prometheus-mysql-exporter-64757ff665-ssb8m 5.14.0-362.24.1.el9_3.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Feb 15 07:18:13 EST 2024 x86_64 GNU/Linux

mysqld_exporter version: output of mysqld_exporter --version

mysqld_exporter, version 0.15.1 (branch: HEAD, revision: cc349684494b5038ec5a52233bdca9eb9291e6f2)
  build user:       root@d89c15b9f5ad
  build date:       20231212-07:55:09
  go version:       go1.21.5
  platform:         linux/amd64
  tags:             unknown

MySQL server version

I think, that I can ignore it, because the issue was not exactly with connection, but with configuration

mysqld_exporter command line flags

/bin/mysqld_exporter --config.my-cnf=/etc/cnf/my.cnf --collect.engine_innodb_status --collect.info_schema.clientstats --collect.info_schema.innodb_cmp --collect.info_schema.innodb_cmpmem --collect.info_schema.innodb_metrics --collect.info_schema.innodb_tablespaces --collect.info_schema.processlist --collect.info_schema.query_response_time --collect.info_schema.schemastats --collect.info_schema.tablestats --collect.info_schema.userstats --no-collect.slave_status

What did you do that produced an error?

In config file, don't describe [client] part, just configure multi-target parts, e.g:

[client.some-db-1]
host=mysqlhost1
port=3306
user=someuser
password=*****
database=temp
[client.some-db-2]
host=mysqlhost2
port=3306
user=someuser
password=*****
database=temp
...

What did you expect to see?

I expect that mysqld exporter won't try to connect to the localhost mysql if I won't configure [client] part, but will configure [client.<somename>] parts

What did you see instead?

ts=2024-05-05T22:16:20.639Z caller=exporter.go:152 level=error msg="Error pinging mysqld" err="dial tcp 127.0.0.1:3306: connect: connection refused"

Additional information

As I use this module inside of Kubernetes cluster, I use this Helm chart: https://artifacthub.io/packages/helm/prometheus-community/prometheus-mysql-exporter/2.4.0
Version of Helm Chart is 2.4.0