How to pass a Troposphere object attribute conditionally?

Question

I'm using Troposphere to build CloudFormation stacks and would like to pass the Elastic Load Balancer

ConnectionSettings

attribute only if it's set in my configuration, otherwise I don't want to specify it.

If I set it to default

None

then I get an error about the value not being of the expected type of

troposphere.elasticloadbalancing.ConnectionSettings

.

I'd rather try to avoid setting an explicit default in the call because it might override other settings.

Idealy, I would like to be able to add attributes to an existing object, e.g.:

lb = template.add_resource(elb.LoadBalancer(

  ...

))



if condition:

  lb.add_attribute(ConnectionSettings = elb.ConnectionSettings(

    ...

  ))

Is there a way to achieve that?

UPDATE: I achieved it using a hidden

Troposphere

method, which works but I'm not happy with:

if condition:

  lb.__setattr__('ConnectionSettings', elb.ConnectionSettings(

    ....

  ))

I'm still interested in a solution which doesn't involve using a private method from outside the module.

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Answer 1

The main README eludes to just using the attribute names like this:

from troposphere import Template
import troposphere.elasticloadbalancing as elb

template = Template()
webelb = elb.LoadBalancer(
    'ElasticLoadBalancer',
    Listeners=[
        elb.Listener(
            LoadBalancerPort="80",
            InstancePort="80",
            Protocol="HTTP",
        ),
    ],
)

if True:
    webelb.ConnectionSettings = elb.ConnectionSettings(IdleTimeout=30)
elasticLB = template.add_resource(webelb)
print(template.to_json())

How to pass a Troposphere object attribute conditionally?

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