r/aws_db_instance: Always pass existing param group from blue to green

[Bexanderthebex]

Rollback Plan

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

Changes to Security Controls

No changes to existing security controls

Description

Pameter groups from a blue deployment are not being passed down to a green deployment if the parameter group did not change creating a drift in the state. This PR fixes that by always passing in the target parameter group to the green deployment

Relations

Closes #49132

References

Output from Acceptance Testing

% make testacc PKG=rds T=TestAccRDSInstance_BlueGreenDeployment
make: Verifying source code with gofmt...
==> Checking that code complies with gofmt requirements...
make: Validating schemas
ok      github.com/hashicorp/terraform-provider-aws/internal/provider/sdkv2     (cached)
ok      github.com/hashicorp/terraform-provider-aws/internal/provider/framework (cached)
make: Running acceptance tests on branch: 🌿 b-aws_db_instance-bg-deploy-target-db-param-group-name-fix 🌿...
TF_ACC=1 go1.26.5 test ./internal/service/rds/... -v -count 1 -parallel 20 -run='TestAccRDSInstance_BlueGreenDeployment'  -timeout 360m -vet=off -buildvcs=false
2026/07/29 17:36:43 Creating Terraform AWS Provider (SDKv2-style)...
2026/07/29 17:36:43 Initializing Terraform AWS Provider (SDKv2-style)...
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateEngineVersion
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateEngineVersion
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateParameterGroup
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateParameterGroup
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateParameterGroupNonTFamilyInstances
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateParameterGroupNonTFamilyInstances
=== RUN   TestAccRDSInstance_BlueGreenDeployment_tags
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_tags
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateInstanceClass
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateInstanceClass
=== RUN   TestAccRDSInstance_BlueGreenDeployment_customParamGroupAndUpdateInstanceClass
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_customParamGroupAndUpdateInstanceClass
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateAndPromoteReplica
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateAndPromoteReplica
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateAndEnableBackups
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateAndEnableBackups
=== RUN   TestAccRDSInstance_BlueGreenDeployment_deletionProtectionBypassesBlueGreen
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_deletionProtectionBypassesBlueGreen
=== RUN   TestAccRDSInstance_BlueGreenDeployment_passwordBypassesBlueGreen
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_passwordBypassesBlueGreen
=== RUN   TestAccRDSInstance_BlueGreenDeployment_updateWithDeletionProtection
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_updateWithDeletionProtection
=== RUN   TestAccRDSInstance_BlueGreenDeployment_outOfBand
=== PAUSE TestAccRDSInstance_BlueGreenDeployment_outOfBand
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateEngineVersion
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateAndPromoteReplica
=== CONT  TestAccRDSInstance_BlueGreenDeployment_tags
=== CONT  TestAccRDSInstance_BlueGreenDeployment_passwordBypassesBlueGreen
=== CONT  TestAccRDSInstance_BlueGreenDeployment_outOfBand
=== CONT  TestAccRDSInstance_BlueGreenDeployment_deletionProtectionBypassesBlueGreen
=== CONT  TestAccRDSInstance_BlueGreenDeployment_customParamGroupAndUpdateInstanceClass
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateInstanceClass
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateAndEnableBackups
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateWithDeletionProtection
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateParameterGroupNonTFamilyInstances
=== CONT  TestAccRDSInstance_BlueGreenDeployment_updateParameterGroup
--- PASS: TestAccRDSInstance_BlueGreenDeployment_passwordBypassesBlueGreen (644.95s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_tags (730.10s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_deletionProtectionBypassesBlueGreen (762.86s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateParameterGroup (1974.71s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateInstanceClass (2085.53s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_outOfBand (2292.62s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateAndEnableBackups (2355.47s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateEngineVersion (2336.85s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateWithDeletionProtection (2461.48s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateParameterGroupNonTFamilyInstances (2502.28s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_customParamGroupAndUpdateInstanceClass (2828.31s)
--- PASS: TestAccRDSInstance_BlueGreenDeployment_updateAndPromoteReplica (3166.37s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/rds        3166.37s
...

[github-actions]

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[github-actions]

✅ Thank you for correcting the previously detected issues! The maintainers appreciate your efforts to make the review process as smooth as possible.