This question isn't really specific to typescript, but that's what i'm using for my project. I am looking for a way to either detect at runtime that a resource will be updated, or just create a dependent resource that will always replace when its source resource is updated. The former would be good enough, but the latter is what i'm trying to accomplish.

Hi Johnny, if you mean you want to encode a dependency between two resources in your program, would

dependsOn

achieve what you want?

based on my testing, that doesn't cause dependent resources to be replaced when upstream resource is updated. just affects order. is that not correct?

Ah I see -- when you say "source resource", you mean the actual cloud resource. So when that changes, you want Pulumi's state to be updated, is that right?

not refresh, no. imagine 2 resources. i update some property of resource 1, causing pulumi to determine that resource needs to be updated. i'd like resource 2 in this case to be replaced, though none of its properties changed. does that make sense?

Hm indeed I'm not sure there's a way to do this neatly at present 🤔

neatly is not a requirement thankfully 🙂

Well, currently I'm struggling to do it at all 😂

that's what i was worrying

I know for e.g.

pulumi.Command

there is

triggers

but that is specific to that resource

just gonna have to keep manually updating the description for the dependent resource. definitely introduces a heap of human error risk, but oh well

There is Pulumi Automation, but obviously that's a chunk of work

To force a replace (delete & recreate) I think you're looking for the replaceOnChanges resource option. There is a downside which is that some input to the dependent resource must depend on the first. Is it not possible to have Resource2's description be defined as an input property, derived from Resource1's outputs? Making these two resources concrete would be helpful, are they resources in AWS, elsewhere?

you could make some resources "reactive" with

intialize

method which is not properly documented here: https://github.com/pulumi/docs/issues/11432

@frial

replaceOnChanges

is definitely the surface area i'm looking to attack. but apart from doing something really heavy handed like sha-ing the entire configuration for

resourceA

and injecting the hash in to the description field for

resourceB

or whatever, there is no mechanism i can devise to ensure that the

replaceOnChanges

field i'm targeting updates if and only if

resourceA

will be created or updated

It would be helpful to make this example a bit more concrete - what is it we're trying to accomplish by destroying and recreating Resource B?

resourceA is an aws lambda, and resourceB is a lambda version. this is only an issue with

aws-native

as

aws

has

publish: true

directly on the lambda resource which works great. but with

aws-native

, the lambda and lambda version being 2 separate resources means it only publishes the initial version, then does not create a new version unless the version resource itself is updated, whereas i need a new version to be created every time any property of the lambda changes (an environment variable, say)

Ah, that makes sense - that seems like a bug in the AWS native provider and a weird quirk. So on the

aws_native.lambda.Function

you pass it in a changing zipFile or other code, but it is a separate

aws_native.lambda.Version

resource that creates a new instance using the current code of the lambda. Would you be able to switch to using the

aws

package's lambda function? It seems like it'll be better behaved. In the mean time I'll flag this issue with the providers team that owns AWS Native for them to create an issue.