https://pulumi.com
Join Slack
Hi, in python aws I'm struggling creating subnets with ipv6_cidr_block (/64) from vpc (/56) ```vpc =...
# getting-started
d
Hi, in python aws I'm struggling creating subnets with ipv6_cidr_block (/64) from vpc (/56)
Copy code
vpc = aws.ec2.Vpc(assign_generated_ipv6_cidr_block=True,...)
I'm looping over AZs
Copy code
for idx, zone in enumerate(availability_zones.names):
    aws.ec2.Subnet(...,
       ipv6_cidr_block = vpc.ipv6_cidr_block.apply(lambda ipv6_block: assign_ipv6_cidr_block(idx,ipv6_block)))
using a utility function:
Copy code
def assign_ipv6_cidr_block(subnet_idx, vpc_ipv6_cidr):
    vpc_ipv6_network = ipaddress.IPv6Network(vpc_ipv6_cidr)
    subnet_ipv6_cidr = list(vpc_ipv6_network.subnets(new_prefix=64))[subnet_idx]
    return str(subnet_ipv6_cidr)
However, I get InvalidSubnet.Conflict, probably because this async stuff causes last value of idx to be used in the call to Subnet(... assign_ipv6_cidr_block(idx)). So, how to fix this code using seperate values of idx (as in a sync world) - or even better use some pulumi built-in functions that just works. Thanks for your help
d
this is a quirk in python that's caught me out before; essentially the lambda references the last assignment of idx. ``````
quick proof of concept in pure python:
Copy code
l = ["a", "b", "c"]
funcs = []
for idx, item in enumerate(l):
    funcs.append(lambda: print(idx, item))

for f in funcs:
    f()
# prints 2 c 2 c 2 c
just checking if something will work, but you might be able to do this to bring forward the idx reference into the loop:
Copy code
Output.all(idx, vpc.ipv6_cidr_block).apply(assign_ipv6_cidr_block)
actually, simpler way is to set idx using a kwarg on the lambda:
Copy code
vpc.ipv6_cidr_block.apply(lambda ipv6_block, idx=idx: assign_ipv6_cidr_block(idx,ipv6_block)))
d
damn, this was just pure python that got me. Thanks a lot Anthony! Saved my day. I ended up using Output.all as above, but had to change my helper function to:
Copy code
def assign_ipv6_cidr_block(arg):
    subnet_idx, vpc_ipv6_cidr = arg
    ...
Again, thank you so much!
d
Aye, it catches many out the first time they encounter the issue
I wonder if Ruff (python's defacto linter) has rules for it
10 Views
Open in Slack
PreviousNext
Powered by

Pulumi Community

No matter how you like to participate in developer communities, Pulumi wants to meet you there. If you want to meet other Pulumi users to share use-cases and best practices, contribute code or documentation, see us at an event, or just tell a story about something cool you did with Pulumi, you are part of our community.

Powered by