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Title
# general
g

gray-knife-50817

09/19/2023, 3:19 PM
Hey all, Wondering if anyone can help advise on this scenario: Objective: Use an 
Output
from 
project A/stack A
in 
project B/stack B
, 
project C/stack C
in multiple files as inputs to resources (keeping things DRY) Current Setup: • Function declared in 
A
which uses 
StackReference
to get an 
Output
from 
A
(seems odd to use 
StackReference
for the current stack but is there a better way?) • Files in 
B
and 
C
import the function from 
A
and save the 
Output
to a variable • The variable gets passed as input for creating resources in 
B
and 
C
• The CI pipeline runs a 
preview
on all stacks (
A
, 
B
, 
C
etc) and fails on 
B
because it doesn't recognise the variable which is dependent on the 
Output
from 
A
, since 
A
hasn't had an 
up
yet to actually produce the 
Output
Am I missing something here in terms of the dependency? Happy to provide more context if helpful. Thanks in advance ✌️
b

billowy-army-68599

09/19/2023, 3:20 PM
Are Stack A, B and C from the same Pulumi project?
g

gray-knife-50817

09/19/2023, 3:23 PM
good question, I should've clarified that - they're each in separate projects. we're using a module approach within the organisation. I'll update the post!
b

billowy-army-68599

09/19/2023, 3:25 PM
So in stack A, wouldn’t you just export an output, then reference it in Stack B and Stack C as a stack reference?
which language SDK are you using?
g

gray-knife-50817

09/19/2023, 3:29 PM
using Python. the thinking was I didn't want to repeat the same code writing the 
StackReference
in multiple places to get the same 
Output
so my logic was to create a function in the module where it came from, to be reused in multiple places elsewhere
b

billowy-army-68599

09/19/2023, 3:36 PM
Generally that’s a 1 line code, but I will often abstract that away into a class, something like this:
Copy code
class VpcStackInfo(pulumi.StackReference):
    vpc_id = pulumi.Output[Any]
    private_subnet_ids = pulumi.Output[Any]
    public_subnet_ids = pulumi.Output[Any]
    cidr_block = pulumi.Output[Any]

    def __init__(self, stack_name: str):
        super().__init__(f"ignistech/vpc/{stack_name}")

        self.vpc_id = self.require_output("vpc_id")  # type: ignore
        self.private_subnet_ids = self.require_output("private_subnet_ids")  # type: ignore
        self.public_subnet_ids = self.require_output("public_subnet_ids")  # type: ignore
        self.cidr_block = self.require_output("cidr_block")  # type: ignore
Then reference it like this:
Copy code
vpc = stackinfo.VpcStackInfo(STACK)
I really try not to use cross referenced functions, you run into lots of issues that way
g

gray-knife-50817

09/19/2023, 4:00 PM
thanks for your help and suggestions I'll give that a go!
I've used the class approach and I think it's better, thanks! the 
preview
is still failing for 
B
because 
A
hasn't been 
up
'd yet I think. But all the changes are going together in the pipeline. Is there something I'm missing for dependency on 
A
by 
B
that needs to be declared for the 
preview
to work?
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