max_open_conns does not seem to work

[markusrydh]

Using mysql provider 1.9.0 and max_open_conns set to 2 I still see a massive amount of mysql connections being used.

Terraform Configuration Files

provider "mysql" {
  version = "~> 1.9.0"

  endpoint = "${module.database.endpoint}:3306"
  username = var.db_master_username
  password = var.db_master_password
  max_open_conns = 2
}

Expected Behavior

No more than 2 open connections from the mysql provider plugin at any time.

Actual Behavior

21 observed connections in parallel, then terraform halts due to too many mysql connections.

Steps to Reproduce

I reproduce this even with parallelism is set to 1.

1. terraform apply -parallelism=1

References

• Add parameters for mysql connection configuration #95

[stevehipwell]

@markusrydh did you find a resolution to this? We've got the exact same issue!

[markusrydh]

Not really, but a workaround was to increase the max number of connections on the DB side. I was using AWS RDS and even for small DBs it is possible to increase it from the (low) default to a level where this no longer was a problem.

[gilesrapkin]

Setting the max_conn_lifetime_sec to 10 seemed to work for me as a workaround. It feels like the provider isn't re-using existing connections on subsequent requests