google_alloydb_instance: fix permadiff on network_config.enable_public_ip

[BBBmau]

Description

Fixes a permadiff issue where google_alloydb_instance continuously shows a diff adding network_config { enable_public_ip = false } even after it has been applied.

Upstream issue: hashicorp/terraform-provider-google#22197

Root Cause

The AlloyDB API omits networkConfig entirely from GET responses when both enable_public_ip and enable_outbound_public_ip are false (the default). This created a perpetual diff cycle:

1. User sets network_config { enable_public_ip = false } and applies
2. On expand, false is treated as an empty value by IsEmptyValue and is not sent to the API
3. API returns nil for networkConfig in subsequent reads
4. Flatten returns nil → state is cleared (network_config = [])
5. Next plan: config has the block, state is empty → diff shown forever

This is the same pattern that was previously fixed for connection_pool_config.

Fix

mmv1/products/alloydb/Instance.yaml:

• Added custom_flatten pointing to a new template for networkConfig
• Added send_empty_value: true to enablePublicIp and enableOutboundPublicIp so that false is sent explicitly to the API (changes expand logic from !IsEmptyValue check to != nil)
• Added default_from_api: true to those same fields so they are treated as computed in state

mmv1/templates/terraform/custom_flatten/alloydb_instance_networkconfig_flatten.go.tmpl (new):

• When the API returns nil or empty networkConfig, preserves the existing state values instead of clearing the block — eliminates the permadiff

Testing

Manually reproduced the scenario described in the issue:

• Set network_config { enable_public_ip = false }
• Without fix: subsequent terraform plan shows the block being added
• With fix: no diff on subsequent plans

Related

• Mirrors the existing fix for connectionPoolConfig: mmv1/templates/terraform/custom_flatten/alloydb_instance_connectionpoolconfig_flatten.go.tmpl

Release Notes

alloydb: fixed permadiff on `network_config` for `google_alloydb_instance` when `enable_public_ip` is set to `false`

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes for commit 0e0db27:

Diff report

Your PR generated the following diffs in downstream repositories:

Repository	Diff Link	Changes
google provider	View Diff	1 file changed, 17 insertions(+), 6 deletions(-)
google-beta provider	View Diff	2 files changed, 99 insertions(+), 6 deletions(-)
terraform-google-conversion	View Diff	2 files changed, 18 insertions(+), 18 deletions(-)

Test report

Analytics

Total Tests	Passed	Skipped	Affected
91	77	3	11

Affected Service Packages

• alloydb

Learn how VCR tests work

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Step 1: Replaying Mode

Action taken

Found 11 affected test(s) by replaying old test recordings. Starting RECORDING based on the most recent commit.

Click here to see the affected tests

• TestAccAlloydbInstance_ObservabilityConfig_Update
• TestAccAlloydbInstance_clientConnectionConfig
• TestAccAlloydbInstance_connectionPoolConfig
• TestAccAlloydbInstance_networkConfigNoPublicIpNoDiff
• TestAccAlloydbInstance_secondaryInstanceUpdateDatabaseFlag
• TestAccAlloydbInstance_secondaryInstanceUpdateMachineConfig
• TestAccAlloydbInstance_secondaryInstanceUpdateQueryInsightConfig
• TestAccAlloydbInstance_stopstart
• TestAccAlloydbInstance_update
• TestAccAlloydbInstance_updateInstanceWithPscInterfaceConfigs
• TestAccAlloydbInstance_updatePscInstanceConfig

View the replaying VCR build log

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Step 2: Recording Mode

Recording Mode	Replaying Rerun	Test Name
✅ Log	✅	TestAccAlloydbInstance_ObservabilityConfig_Update
✅ Log	✅	TestAccAlloydbInstance_clientConnectionConfig
✅ Log	✅	TestAccAlloydbInstance_connectionPoolConfig
✅ Log	✅	TestAccAlloydbInstance_networkConfigNoPublicIpNoDiff
✅ Log	✅	TestAccAlloydbInstance_secondaryInstanceUpdateDatabaseFlag
✅ Log	✅	TestAccAlloydbInstance_secondaryInstanceUpdateMachineConfig
✅ Log	✅	TestAccAlloydbInstance_secondaryInstanceUpdateQueryInsightConfig
✅ Log	✅	TestAccAlloydbInstance_stopstart
✅ Log	✅	TestAccAlloydbInstance_update
✅ Log	✅	TestAccAlloydbInstance_updateInstanceWithPscInterfaceConfigs
✅ Log	✅	TestAccAlloydbInstance_updatePscInstanceConfig

🟢 All tests passed!

View the recording VCR build log or the debug logs folder for detailed results.

@BBBmau VCR tests complete for 0e0db27!