❓ Issue: mysqld_exporter fails to expose metrics when validate_password plugin is enabled (MySQL 8.0.30)

[dscarj]

Environment
mysqld_exporter version: 0.15.0

MySQL version: 8.0.30

Plugin: validate_password is enabled and cannot be disabled (security policy requirement)

OS: CentOS 7

Architecture: x86_64

Startup method: running binary directly

🧵 Description
I’m using mysqld_exporter to monitor a MySQL 8.0.30 instance that has the validate_password plugin enabled (mandatory in production due to security compliance). While the exporter starts up normally and listens on port 9104, accessing the /metrics endpoint immediately fails with the following error:

An error has occurred while serving metrics:

7 error(s) occurred:

• [from Gatherer Added docker file #2] collected metric "mysql_global_variables_validate_password_check_user_name" { gauge:{value:1}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_variables_validate_password_length" { gauge:{value:8}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_variables_validate_password_mixed_case_count" { gauge:{value:1}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_variables_validate_password_number_count" { gauge:{value:1}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_variables_validate_password_special_char_count" { gauge:{value:1}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_status_validate_password_dictionary_file_last_parsed" { untyped:{value:1.744627442e+09}} was collected before with the same name and label values
• [from Gatherer Added docker file #2] collected metric "mysql_global_status_validate_password_dictionary_file_words_count" { untyped:{value:0}} was collected before with the same name and label values
  This completely breaks Prometheus integration as no metrics can be scraped.

🔍 What I’ve Tried
Tried minimal --collect.* flags to avoid metric overlap (e.g. only global_status, global_variables)

Ensured exporter MySQL user has appropriate permissions (PROCESS, REPLICATION CLIENT, SELECT, and SELECT on performance_schema)

Verified exporter can connect to MySQL (no password issues)

Confirmed validate_password variables appear in SHOW GLOBAL VARIABLES

Cannot disable the plugin in our environment (production restriction)

❗ Critical Problem
This is not just a duplicate-metric warning — once the validate_password plugin is enabled, the exporter completely fails to serve /metrics, meaning the service becomes unusable for monitoring.

❓ Questions
Is this a known issue in mysqld_exporter 0.15.0?

Has this been fixed in 0.15.1 or a newer version?

Is there a way to exclude or skip certain MySQL variables like those from validate_password?

Are there any recommended workarounds or best practices for this case?