Cannot "un-set" parameter group values

[hashibot]

This issue was originally opened by @chrisrlong as hashicorp/terraform#13321. It was migrated here as part of the provider split. The original body of the issue is below.

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Hi there,

Terraform Version

0.7.2 - Terraform v0.9.3-dev (0de008e07d41ad4635e7be7727b88109623f2828+CHANGES)

Affected Resource(s)

aws_db_parameter_group

If this issue appears to affect multiple resources, it may be an issue with Terraform's core, so please mention this.

Terraform Configuration Files

resource "aws_db_parameter_group" "default" {
  name = "${var.name}-db-parameter-group"
  family = "${var.rds_parameter_family}"
  description = "Database parameters for ${var.name}"
  parameter {
    name = "binlog_cache_size"
    value = "1048576"
    apply_method = "pending-reboot"
  }
  parameter {
    name = "binlog_checksum"
    value = "crc32"
    apply_method = "pending-reboot"
  }
  parameter {
    name = "binlog_format"
    value = "MIXED"
    apply_method = "pending-reboot"
  }
...

Expected Behavior

If a parameter has been set and now removed:
parameter.1212351445.name: "general_log" => ""
parameter.1918306725.name: "log_output" => ""
parameter.2107150943.name: "innodb_lru_scan_depth" => ""
parameter.3306308666.name: "log_queries_not_using_indexes" => ""
parameter.245681620.name: "max_allowed_packet" => ""

terraform apply should unset the values and finish normally.

Actual Behavior

terraform finishes normally, however the values are not changed, and the same removals are in the next plan/apply.

(to stop the cycle, I had to login to the AWS console and find the parameters, then check the "reset value" button)

Steps to Reproduce

Set some parameters in the parameter group.
remove some config (exapmles above) and run terraform apply.

References

Could be related to/with

• AWS Lambda layers not reference-able in lambda function #8818

[longwave]

Also run into this. I suspect that Terraform is just doing the equivalent of aws rds modify-db-parameter-group here, but for parameters that exist in state but have since been removed, it needs the equivalent of aws rds reset-db-parameter-group --no-reset-all-parameters.

[hegyre]

Just ran into the same issue.
Even the AWS console had the issue...

Need to use aws-cli:

aws rds reset-db-parameter-group --db-parameter-group-name <value> --parameters ParameterName="max_allowed_packet",ApplyMethod="immediate"

[robinbowes]

We're running into this quite a lot at the moment. Any chance of a fix?

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!