New variables: create_parameter_group and parameter_group_name

[y3ti]

what

• Add redis family suffix to parameter group name
• Add new variables: create_parameter_group and parameter_group_name

why

This module doesn't currently support major version upgrades of Redis (eg, 6.x to. 7.x) because:

• Parameter groups are major-version specific, so when a user changes var.family from redis6 to redis7, Terraform needs to create a new parameter group. Without create_before_destroy, Terraform tries to first destroy the old Param group which fails because it's currently in use
• Parameter groups must have unique names across families. When Terraform tries to create a new param group for redis7, it fails because it tries to do so using the same name as the old param group.

I have decided to add "redis cluster family" as a suffix. AWS follows a similar convention for default parameter groups, using names such as:

• default.redis6.x
• default.redis7

Since using . is not possible, I have opted to use - instead.

To prevent any breaking changes, I have introduced a new variable called parameter_group_name. By setting this variable to the current parameter group name, you can prevent any terraform configuration drift.

We can also reuse existing parameter groups.

If we want to use the default parameter group created by AWS (default.redis7)

create_parameter_group = false
engine                 = "redis7"

If we want to use any other existing parameter group:

create_parameter_group = false
parameter_group_name   = "existing-parameter-group-name"

references

Resolves https://github.com/cloudposse/terraform-aws-elasticache-redis/issues/178

I see that other people tried to solve this problem before (see references), but the pull requests were not merged yet:

• https://github.com/cloudposse/terraform-aws-elasticache-redis/pull/159
• https://github.com/cloudposse/terraform-aws-elasticache-redis/pull/189
• https://github.com/cloudposse/terraform-aws-elasticache-redis/pull/201
• https://github.com/cloudposse/terraform-aws-elasticache-redis/pull/208

[y3ti]

I added new variable create_parameter_group, the module can also use default parameter group.

[aknysh]

/terratest

[aknysh]

/terratest