[WIP] f/ipam-subnet-reservations: Support VPC Resource Planning IPAM Pools + IPAM Subnet Reservations

[rohank25]

Rollback Plan

If a change needs to be reverted, we will publish an updated version of the library.

Changes to Security Controls

None

Description

• Support provisioning of VPC Resource Planning IPAM Pools
• Support provisioning of subnet cidrs from IPAM Pools
• Graceful deletion of IPAM pool cidrs with VPC / Subnet allocations.

Notes

I faced issues when attempting to delete ipam pool cidrs (to simulate a full end-to-end configuration) because of eventual consistency issues with ipam pool allocations. My attempt at resolving this is to check which vpc / subnet allocations are within the cidr, and wait for those to be released (takes 20 mins).

I still need to fix eventual consistency issues when provisioning vpc / subnet resources across accounts / regions.

Unfortunately, running acceptance tests takes a while since IPAM is restricted to 1 per account. If you have any suggestions on how to overcome this issue, please let me know, thanks!

Relations

Closes #34615

References

Output from Acceptance Testing

WIP

% make testacc TESTS=TestAccIPAMPool_serial PKG=ec2                                  
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
make: Running acceptance tests on branch: 🌿 f-ipam-subnet-reservations 🌿...
TF_ACC=1 go1.24.8 test ./internal/service/ec2/... -v -count 1 -parallel 20 -run='TestAccIPAMPool_serial'  -timeout 360m -vet=off
2025/10/19 18:08:37 Creating Terraform AWS Provider (SDKv2-style)...
2025/10/19 18:08:37 Initializing Terraform AWS Provider (SDKv2-style)...
=== RUN   TestAccIPAMPool_serial
=== PAUSE TestAccIPAMPool_serial
=== CONT  TestAccIPAMPool_serial
=== RUN   TestAccIPAMPool_serial/ResourcePlanningVPC
=== RUN   TestAccIPAMPool_serial/ResourcePlanningVPC/ipv4
=== RUN   TestAccIPAMPool_serial/ResourcePlanningVPC/ipv6
=== RUN   TestAccIPAMPool_serial/ResourcePlanningVPC/sourceResourceUpdate
--- PASS: TestAccIPAMPool_serial (3459.31s)
    --- PASS: TestAccIPAMPool_serial/ResourcePlanningVPC (3459.31s)
        --- PASS: TestAccIPAMPool_serial/ResourcePlanningVPC/ipv4 (1145.17s)
        --- PASS: TestAccIPAMPool_serial/ResourcePlanningVPC/ipv6 (1148.48s)
        --- PASS: TestAccIPAMPool_serial/ResourcePlanningVPC/sourceResourceUpdate (1165.66s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/ec2        3463.725s...

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