Hi folks, I'm trying to create custom resources in a Pulumi script written in Python using dynamic resource providers. But I can't figure out how to add outputs that aren't also inputs. The Pulumi documentation is not really helpful and I can't find a Python example of a dynamic resource with additional outputs. I found a good explanation on how to write dynamic providers on YouTube but it's in TypeScript. Does someone know how to do this?

The second parameter to

CreateResult

is just a map object. So you should be able to do something like:

class MyProvider(ResourceProvider):
    def create(self, inputs):
        outputs = {}
        outputs["x"] = inputs["x"]
        outputs["y]" = "some value"
        return CreateResult("SomeID", outputs)

I already did this, but then I'll get the error, that the resource object (not the provider object), doesn't have this attribute.

Oh right, I think you need to declare the attributes on the resource object. Something like:

class X(dyn.Resource):
    x: Output[str]
    y: Output[str]

Makes sense. But now I get a completely strange error:

error: Exception calling application: unsupported operand type(s) for <<: 'int' and 'float'

Well that's somewhere is expecting an int and you've got a float value. That may be due to pulumi deserialsing the outputs to a float because it didn't know you wanted an int because you we're missing an annotation. Hard to say without seeing the code.

I only added the additional lines. I never use any

int

or

float

, apart from an input (

length

) that did not produce this error previously. In the create method I set set it to

"test"

as you described above.

class RSAKeyPair(Resource):
    file_name: Output[str]
    file_location: Output[str]
    length: Output[int]
    public_key_data: Output[str]

    def __init__(self, name: str, args: RSAKeyPairInputs, opts = None):
        ins = vars(args)
        ins["public_key_data"] = None
        super().__init__(RSAKeyPairProvider(), name, ins, opts)

That looks ok. Is there anywhere in your code that using the shift operator (

<<

)? I'd look around that and maybe add some type casts

I have found the issue: For some reason an input gets type casted to a

float

, and therefor a method expecting an

int

creates that error. But that only happens once the initial error - the missing attribute of the resource - is resolved. That confused me. Now it works perfectly. Thank you very much! 🙂