CloudFormation conditional EMR instances - amazon-web-services

Question

I struggle a bit with the use of conditionals in CF templates, and I would like to conditionally specify EMR cluster instances groups or fleets in the most concise way.
This builds w/o error. It chooses to use instance groups if prod, or instance fleets if non-prod using two separate conditionals:
Parameters:
EnvironmentName:
Type: String
Description: 'Example: ci, qa, stage, prod'
Conditions:
IsPreProd: !Or
[!Equals [!Ref EnvironmentName, ci], !Equals [!Ref EnvironmentName, qa]]
IsProd: !Or
[!Equals [!Ref EnvironmentName, stage], !Equals [!Ref EnvironmentName, prod]]
Resources:
EMRCluster:
Type: 'AWS::EMR::Cluster'
Properties:
Instances:
CoreInstanceGroup:
!If
- IsProd
- InstanceCount: 1
InstanceType: m5.8xlarge
Market: ON_DEMAND
Name: CoreInstance
- !Ref "AWS::NoValue"
CoreInstanceFleet:
!If
- IsPreProd
- InstanceTypeConfigs:
- InstanceType: m5.8xlarge
TargetOnDemandCapacity: 1
TargetSpotCapacity: 1
LaunchSpecifications:
SpotSpecification:
TimeoutAction: SWITCH_TO_ON_DEMAND
TimeoutDurationMinutes: 10
- !Ref "AWS::NoValue"
I would like to use just a single conditional, like below, except the build fails telling me 'YAML not well-formed' on the line where the 'If' is. If I implement it like above, I would end up having four separate conditionals since I also have to add master instance groups or fleets as well. Is is possible to do it like this all as one conditional?
Parameters:
EnvironmentName:
Type: String
Description: 'Example: ci, qa, stage, prod'
Conditions:
IsProd: !Or
[!Equals [!Ref EnvironmentName, stage], !Equals [!Ref EnvironmentName, prod]]
Resources:
EMRCluster:
Type: 'AWS::EMR::Cluster'
Properties:
Instances:
- !If
- IsProd
- CoreInstanceGroup:
InstanceCount: 1
InstanceType: m5.8xlarge
Market: ON_DEMAND
Name: CoreInstance
- CoreInstanceFleet:
InstanceTypeConfigs:
- InstanceType: m5.8xlarge
TargetOnDemandCapacity: 1
TargetSpotCapacity: 1
LaunchSpecifications:
SpotSpecification:
BlockDurationMinutes: 60
TimeoutAction: SWITCH_TO_ON_DEMAND
TimeoutDurationMinutes: 10

Answer 1

Instances is not a list. You don't need - before !If:
Resources:
EMRCluster:
Type: 'AWS::EMR::Cluster'
Properties:
Instances:
!If
- IsProd
- CoreInstanceGroup:
InstanceCount: 1
InstanceType: m5.8xlarge
Market: ON_DEMAND
Name: CoreInstance
- CoreInstanceFleet:
InstanceTypeConfigs:
- InstanceType: m5.8xlarge
TargetOnDemandCapacity: 1
TargetSpotCapacity: 1
LaunchSpecifications:
SpotSpecification:
BlockDurationMinutes: 60
TimeoutAction: SWITCH_TO_ON_DEMAND
TimeoutDurationMinutes: 10