The parameter CacheSubnetGroupName must be provided and must not be blank - amazon-web-services

Question

I use the module, https://github.com/cloudposse/terraform-aws-elasticache-redis to provision elasticache redis. Below are the errors when I run terraform apply. I have no clue of these errors.
Terraform version: v0.13.5
module.redis.aws_elasticache_parameter_group.default[0]: Creating...
module.redis.aws_elasticache_subnet_group.default[0]: Creating...
Error: Error creating CacheSubnetGroup: InvalidParameterValue: The parameter CacheSubnetGroupName must be provided and must not be blank.
status code: 400, request id: a1ab57b1-fa23-491c-aa7b-a2d3804014c9
Error: Error creating Cache Parameter Group: InvalidParameterValue: The parameter CacheParameterGroupName must be provided and must not be blank.
status code: 400, request id: 9abc80b6-bd3b-46fd-8b9e-9bf14d1913eb
redis.tf:
module "redis" {
source = "git::https://github.com/cloudposse/terraform-aws-elasticache-redis.git?ref=tags/0.25.0"
availability_zones = var.azs
vpc_id = module.vpc.vpc_id
allowed_security_groups = [data.aws_security_group.default.id]
subnets = module.vpc.private_subnets
cluster_size = var.redis_cluster_size #number_cache_clusters
instance_type = var.redis_instance_type
apply_immediately = true
automatic_failover_enabled = false
engine_version = var.engine_version
family = var.family
replication_group_id = var.replication_group_id
elasticache_subnet_group_name = var.elasticache_subnet_group_name
#enabled = true
enabled = var.enabled
#at-rest encryption is to increase data security by encrypting on-disk data.
at_rest_encryption_enabled = var.at_rest_encryption_enabled
#in-transit encryption protects data when it is moving from one location to another.
transit_encryption_enabled = var.transit_encryption_enabled
cloudwatch_metric_alarms_enabled = var.cloudwatch_metric_alarms_enabled
parameter = [
{
#Keyspace notifications send events for every operation affecting the Redis data space.
name = "notify-keyspace-events"
value = "lK"
}
]
context = module.this.context
}
context.tf:
module "this" {
source = "git::https://github.com/cloudposse/terraform-null-label.git?ref=tags/0.19.2"
enabled = var.enabled
namespace = var.namespace
environment = var.environment
stage = var.stage
name = var.name
delimiter = var.delimiter
attributes = var.attributes
tags = var.tags
additional_tag_map = var.additional_tag_map
label_order = var.label_order
regex_replace_chars = var.regex_replace_chars
id_length_limit = var.id_length_limit
context = var.context
}
variable "context" {
type = object({
enabled = bool
namespace = string
environment = string
stage = string
name = string
delimiter = string
attributes = list(string)
tags = map(string)
additional_tag_map = map(string)
regex_replace_chars = string
label_order = list(string)
id_length_limit = number
})
default = {
enabled = true
namespace = null
environment = null
stage = null
name = null
delimiter = null
attributes = []
tags = {}
additional_tag_map = {}
regex_replace_chars = null
label_order = []
id_length_limit = null
}
description = <<-EOT
Single object for setting entire context at once.
See description of individual variables for details.
Leave string and numeric variables as `null` to use default value.
Individual variable settings (non-null) override settings in context object,
except for attributes, tags, and additional_tag_map, which are merged.
EOT
}
variable "enabled" {
type = bool
default = true
description = "Set to false to prevent the module from creating any resources"
}
variable "namespace" {
type = string
default = null
description = "Namespace, which could be your organization name or abbreviation, e.g. 'eg' or 'cp'"
}
variable "environment" {
type = string
default = null
description = "Environment, e.g. 'uw2', 'us-west-2', OR 'prod', 'staging', 'dev', 'UAT'"
}
variable "stage" {
type = string
default = null
description = "Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release'"
}
variable "name" {
type = string
default = null
description = "Solution name, e.g. 'app' or 'jenkins'"
}
variable "delimiter" {
type = string
default = null
description = <<-EOT
Delimiter to be used between `namespace`, `environment`, `stage`, `name` and `attributes`.
Defaults to `-` (hyphen). Set to `""` to use no delimiter at all.
EOT
}
variable "attributes" {
type = list(string)
default = []
description = "Additional attributes (e.g. `1`)"
}
variable "tags" {
type = map(string)
default = {}
description = "Additional tags (e.g. `map('BusinessUnit','XYZ')`"
}
variable "additional_tag_map" {
type = map(string)
default = {}
description = "Additional tags for appending to tags_as_list_of_maps. Not added to `tags`."
}
variable "label_order" {
type = list(string)
default = null
description = <<-EOT
The naming order of the id output and Name tag.
Defaults to ["namespace", "environment", "stage", "name", "attributes"].
You can omit any of the 5 elements, but at least one must be present.
EOT
}
variable "regex_replace_chars" {
type = string
default = null
description = <<-EOT
Regex to replace chars with empty string in `namespace`, `environment`, `stage` and `name`.
If not set, `"/[^a-zA-Z0-9-]/"` is used to remove all characters other than hyphens, letters and digits.
EOT
}
variable "id_length_limit" {
type = number
default = null
description = <<-EOT
Limit `id` to this many characters.
Set to `0` for unlimited length.
Set to `null` for default, which is `0`.
Does not affect `id_full`.
EOT
}

Answer 1

Open up the context.tf and set variable "enabled" to true if you want the module to create resources for you, including the subnet group.
Otherwise, you have to create all per-requsite resources yourselves, which includes elasticache_subnet_group_name.

Answer 2

I found the problem. The default values of namespace/environment/stage/name in context.tf are null. That causes the problem. Set these values solved the problem.

Answer 3

You need to provide module input which can be found on the link you provided.
For instance :
Error: Error creating CacheSubnetGroup: InvalidParameterValue: The parameter CacheSubnetGroupName must be provided and must not be blank. status code: 400, request id: a1ab57b1-fa23-491c-aa7b-a2d3804014c9
In this case, you need to set elasticache_subnet_group_name, and so on: