Conditionally define Elastic Beanstalk environment variable using CloudFormation - amazon-web-services

Question

I want to create an Elastic Beanstalk using CloudFormation template. I want to define an environment variable ENV_VAR_1 and set it's value to value of template parameter var1. But don't want ENV_VAR_1 to exist at all if var1 is an empty string. I.e. I don't want ENV_VAR_1 with no value.
First I tried the Conditions, but I get "Encountered unsupported property Condition" during creation of ElasticBeanstalkEnvironment resource.
Parameters:
var1:
Type: String
Conditions:
isVar1Empty: !Equals [ !Ref var1, "" ]
Resources:
ElasticBeanstalkEnvironment:
Type: 'AWS::ElasticBeanstalk::Environment'
Properties:
OptionSettings:
- Namespace: 'aws:elasticbeanstalk:application:environment'
Condition: isVar1Empty
OptionName: ENV_VAR_1
Value: !Ref var1
Then I tried AWS::NoValue
Parameters:
var1:
Type: String
Resources:
ElasticBeanstalkEnvironment:
Type: 'AWS::ElasticBeanstalk::Environment'
Properties:
OptionSettings:
- Namespace: 'aws:elasticbeanstalk:application:environment'
OptionName: ENV_VAR_1
Value: !If [[!Equals [ !Ref var1, "" ]], !Ref 'AWS::NoValue', !Ref var1]
and many permutation combinations of this. With the same result: When var1 is empty, Elastic Beanstalk gets created with ENV_VAR_1 set to ""

Answer 1

Conditions are going to be applied at the Resource level...currently, you cannot apply a condition to a specific property.
What you could do to satisfy these exact requirements (and this is a bit ugly), is create two conditions, one negating the other. Then with these two conditions, have them conditionally create the specific resource.
Parameters:
var1:
Type: String
Conditions:
isVar1Empty: !Equals [ !Ref var1, "" ]
isVar1NonEmpty: !Not [ !Equals [ !Ref var1, "" ] ]
Resources:
ElasticBeanstalkEnvironmentWithVar1:
Type: 'AWS::ElasticBeanstalk::Environment'
Condition: isVar1NonEmpty
Properties:
OptionSettings:
- Namespace: 'aws:elasticbeanstalk:application:environment'
OptionName: ENV_VAR_1
Value: !Ref var1
ElasticBeanstalkEnvironmentWithoutVar1:
Type: 'AWS::ElasticBeanstalk::Environment'
Condition: isVar1Empty
Properties:
OptionSettings:
- Namespace: 'aws:elasticbeanstalk:application:environment'
Like I said...a bit ugly. Note that this will only really work well if you have one or two variables like this. As soon as you add a second or third 'optional' parameter, this quickly starts spiraling out of control.
A better option might be to generate your CloudFormation template using a templating library like mustache.

Answer 2

Another workaround to handle conditions at option level:
Conditions:
CreateProdResources: !Equals [!Ref Env, "prod"]
EBEnvironment:
Type: AWS::ElasticBeanstalk::Environment
Properties:
OptionSettings:
- Namespace : "aws:elasticbeanstalk:command"
OptionName: Timeout
Value : 1200
- Namespace : !If [CreateProdResources, "aws:elbv2:listener:443", "aws:elasticbeanstalk:command"]
OptionName: !If [CreateProdResources, Protocol, Timeout]
Value : !If [CreateProdResources, HTTPS, 1200]
- Namespace : !If [CreateProdResources, "aws:elbv2:listener:443", "aws:elasticbeanstalk:command"]
OptionName: !If [CreateProdResources, SSLPolicy, Timeout]
Value : !If [CreateProdResources, "ELBSecurityPolicy-2016-08", 1200]
- Namespace : !If [CreateProdResources, "aws:elbv2:listener:443", "aws:elasticbeanstalk:command"]
OptionName: !If [CreateProdResources, SSLCertificateArns, Timeout]
Value : !If [CreateProdResources, !Ref ACMCertificate, 1200]
Repeated options are considered only once in Elastic Beanstalk.