Cloudformation - ElastiCache::SubnetGroup not honouring resource name - amazon-web-services

Question

I have a weird issue with CloudFormation that seems either to be a bug, or more likely - i've missed something pretty basic.
I have the following template (a snippet) defining two subnets and a subnet group as follow:
...
"redissubnet1": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"CidrBlock": "10.0.8.0/24",
"AvailabilityZone": "us-east-1c",
"VpcId": {
"Ref": "myVPC"
},
"Tags": [
{
"Key": "Name",
"Value": "redissubnet1"
}
]
}
},
"redissubnet2": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"CidrBlock": "10.0.9.0/24",
"AvailabilityZone": "us-east-1c",
"VpcId": {
"Ref": "myVPC"
},
"Tags": [
{
"Key": "Name",
"Value": "redissubnet2"
}
]
}
},
"SubnetGroupName": {
"Type": "AWS::ElastiCache::SubnetGroup",
"Properties": {
"Description": "Subnet group for main application redis elastic cache",
"SubnetIds": [
{
"Ref": "redissubnet1"
},
{
"Ref": "redissubnet2"
}
]
}
}
...
All resources are created, yet the SubnetGroup name - "SubnetGroupName" - is not honoured. AWS auto-assigns a name in the format [a-z]-[a-z]-[a-z0-9]
Has anyone encountered this?
What I'm actually trying to do is reference this subnet group by name in the creation of an ElastiCache::Cluster - however because the resource name is not honoured I can't do so.
Anyone have any ideas? All help gratefully received :)

Answer 1

Answer was to reference the subnet group name in the elastic cache resource, as follows:
{
"subnet1": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"CidrBlock": "10.0.8.0/24",
"AvailabilityZone": "us-east-1c",
"VpcId": {
"Ref": "myVPC"
},
"Tags": [{
"Key": "Name",
"Value": "subnet1"
}]
}
},
"subnet2": {
"Type": "AWS::EC2::Subnet",
"Properties": {
"CidrBlock": "10.0.9.0/24",
"AvailabilityZone": "us-east-1c",
"VpcId": {
"Ref": "myVPC"
},
"Tags": [{
"Key": "Name",
"Value": "subnet2"
}]
}
},
"redis1": {
"Type": "AWS::ElastiCache::SubnetGroup",
"Properties": {
"Description": "Subnet group for main application redis elastic cache",
"SubnetIds": [{
"Ref": "subnet1"
}, {
"Ref": "subnet2"
}]
}
},
"mainredis": {
"Type": "AWS::ElastiCache::CacheCluster",
"Properties": {
"AutoMinorVersionUpgrade": "true",
"CacheNodeType": "cache.t2.small",
"CacheSubnetGroupName": {
"Ref": "redis1"
},
"ClusterName": "mainredis",
"Engine": "redis",
"NumCacheNodes": "1",
"Port": "6379",
"Tags": [{
"Key": "Name",
"Value": "mainredis"
}, {
"Key": "Function",
"Value": "Main redis store"
}],
"VpcSecurityGroupIds": [
"redissecuritygroup"
]
}
}
}