chore(infra): reconcile production database upgrade

[tasoo-oos]

Description

• 운영 RDS의 PostgreSQL 18.4 Blue/Green 전환 결과를 Terraform에 반영합니다.
• PostgreSQL 18 운영 파라미터 그룹과 보관 중인 PostgreSQL 14 논리 복제 파라미터 그룹을 관리합니다.
• 운영 DB 스토리지를 30 GiB gp3, autoscaling 최대 100 GiB로 맞춥니다.
• 전환 완료 후 wal_receiver_timeout을 RDS 기본값 30초로 복원합니다.

Additional context

• timeout 복원 plan은 파라미터 그룹 in-place 변경 1건이며 리소스 교체·삭제가 없습니다.
• 적용 후 전체 terraform plan 결과는 No changes입니다.
• 운영 DB는 available, 파라미터 그룹은 in-sync 상태입니다.
• PostgreSQL 14 파라미터 그룹은 old blue 보관 기간 종료 후 별도 승인으로 제거합니다.

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Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines
• Read the Contributing Guidelines and follow the Commit Convention
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves.
• Run relevant validation: terraform fmt -check, terraform validate, and full terraform plan.

Closes TAS-2888

Summary by CodeRabbit

• Infrastructure
  • Upgraded the application database to PostgreSQL 18.4.
  • Increased available database storage capacity from 10–25 GB to 30–100 GB.
  • Added migration and compatibility settings to support a controlled database upgrade with minimal disruption.
  • Improved database replication configuration for the upgrade process and ongoing PostgreSQL 18 operation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 6fc487ed-1293-4da5-b56d-6727c6d8a35d

📥 Commits

Reviewing files that changed from the base of the PR and between 3d2b2b8 and e155921.

📒 Files selected for processing (1)

• infra/aws/storage/database.tf

💤 Files with no reviewable changes (1)

• infra/aws/storage/database.tf

Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review.

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📝 Walkthrough

Walkthrough

The change adds PostgreSQL 14 and PostgreSQL 18 parameter groups for logical replication. It upgrades the RDS instance to PostgreSQL 18.4, increases storage limits, and attaches the PostgreSQL 18 parameter group.

Changes

PostgreSQL migration

Layer / File(s)	Summary
Replication parameter groups infra/aws/storage/database.tf	Adds PostgreSQL 14 source settings and PostgreSQL 18 target settings for logical replication and SSL. The PostgreSQL 18 group omits wal_receiver_timeout.
RDS target upgrade infra/aws/storage/database.tf	Updates the instance to PostgreSQL 18.4, changes storage from 10–25 GB to 30–100 GB, and attaches the PostgreSQL 18 parameter group.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to e1559

This PR records the completed PostgreSQL upgrade, storage settings, retained legacy replication configuration, and timeout restoration in Terraform. With validation complete and the database reported healthy, no actionable merge-blocking risk remains beyond normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: reconciling the production database upgrade in infrastructure. It is concise and specific enough for repository history.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch t2888-db-migration

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[doyoon323]

수고하셨습니다~