Subnets are not associated with VPCs when using AWS

[Michael Fraenkel]

When I attempted to bootstrap juju on AWS, it failed with the following:

ERROR fetching hosted model spaces: adding subnet "10.0.1.0/24": subnet "10.0.1.0/24" already exists
2017-06-22 18:01:20 DEBUG cmd supercommand.go:459 error stack:
github.com/juju/juju/state/subnets.go:225: subnet "10.0.1.0/24" already exists
github.com/juju/juju/state/subnets.go:238:
github.com/juju/juju/state/subnets.go:238: adding subnet "10.0.1.0/24"
github.com/juju/juju/state/spacesdiscovery.go:78:
github.com/juju/juju/state/spacesdiscovery.go:51:
github.com/juju/juju/agent/agentbootstrap/bootstrap.go:221: fetching hosted model spaces
github.com/juju/juju/cmd/jujud/agent/agent.go:102:
2017-06-22 18:01:20 DEBUG juju.cmd.jujud main.go:186 jujud complete, code 0, err <nil>
14:01:21 ERROR juju.cmd.juju.commands bootstrap.go:499 failed to bootstrap model: subprocess encountered error code 1

My account has 4 VPCs and 17 subnets across them. The subnet failure above is owned by one of the other VPCs (not the default one).
I added some debug code,
2017-06-22 18:01:20 INFO XXX subnets.go:209 AddSubnet state.SubnetInfo{ProviderId:"subnet-9c429dfb", ProviderNetworkId:"", CIDR:"10.0.1.0/24", VLANTag:0, AvailabilityZone:"us-east-1a", SpaceName:""}

The ProviderNetworkId is "". The comment states that

// ProviderNetworkId holds the provider id of the network
// containing this subnet, for example VPC id for EC2.

Something is amiss.

[Michael Fraenkel (mfraenkel)]

I added some debug and it becomes more obvious what the issue is.
Like I stated, I have 4 VPCs, there are subnets across them that have identical CIDR ranges. The list of subnets to add are coming from mutiple VPCs. When they are added, a duplicate is detected because only the CIDR is taken into consideration.
Here are the subnets being added, I have set the NetworkId to be the VPC id.

AddSubnet() state.SubnetInfo{ProviderId:"subnet-9c429dfb", ProviderNetworkId:"vpc-327dc555", CIDR:"10.0.1.0/24", VLANTag:0, AvailabilityZone:"us-west-2b", SpaceName:""}
AddSubnet() state.SubnetInfo{ProviderId:"subnet-2bb24773", ProviderNetworkId:"vpc-c29f1da6", CIDR:"10.0.1.0/24", VLANTag:0, AvailabilityZone:"us-west-2c", SpaceName:""}

Subnet() &state.subnetDoc{DocID:"45cb8652-b8ea-4daf-8edd-68aa5b87e4ce:10.0.1.0/24", ModelUUID:"45cb8652-b8ea-4daf-8edd-68aa5b87e4ce", Life:0, ProviderId:"subnet-9c429dfb", ProviderNetworkId:"vpc-327dc555", CIDR:"10.0.1.0/24", VLANTag:0, AvailabilityZone:"us-west-2b", IsPublic:false, SpaceName:""}

[John A Meinel (jameinel)]

https://github.com/juju/juju/pull/7565