Pundi cara nangani database migrations ing CI/CD?

Question

Accepted Answer

**Database migrations** (perubahan schema) minangka salah sawijining bagian sing paling angel ing CI/CD — beda karo kode aplikasi sing stateless, basis data nampung **state** sing ora bisa diganti utawa dibatalke. Nangani migrations kanthi ati-ati (otomasi, backward compatibility, pola sing aman) kaharusan kanggo deployment sing bisa dipercaya.

## Napa database migrations iku angel

```text
App code is stateless (replace it, roll back freely). DATABASES hold STATE:
  → can't just "roll back" a migration that dropped a column or transformed data
    (the data may be gone) → rollbacks are risky/impossible for destructive changes
  → during deployment, OLD and NEW app code may run SIMULTANEOUSLY (rolling deploy) —
    both must work with the database schema at that moment
→ Schema changes need careful coordination with code deployment.
```

## Ngotomasi migrations ing pipeline

```text
→ Migrations defined as CODE (versioned migration files; Flyway, Liquibase, ORM tools)
→ Run migrations as a pipeline STEP (apply pending migrations on deploy)
→ Migrations are versioned and applied in order, idempotently
→ Test migrations in staging before production
```

## Pola migration sing aman (backward compatibility)

```text
KEY PRINCIPLE: make migrations BACKWARD-COMPATIBLE so old AND new code both work during
the transition. Use the EXPAND-CONTRACT (parallel change) pattern:
  1. EXPAND → add the new schema (e.g. add a new column) — old code still works
  2. MIGRATE → deploy code that writes to both / reads new; backfill data
  3. CONTRACT → once all code uses the new schema, remove the old (in a LATER deploy)
→ NEVER drop/rename in the same deploy that needs it gone — split across deploys.
→ This enables zero-downtime deploys and safe rollbacks.
```

## Napa iki penting

Pamahaman babagan cara nangani database migrations ing CI/CD kapentig amerga **migrations minangka salah sawijining bagian sing paling angel lan beras tinggi ing automated deployment**, dadi iki pengetahuan praksis sing berharga kanggo delivery sing bisa dipercaya.

Challenge inti yaiku, beda karo kode aplikasi stateless (sing bisa diganti lan dibatalke kanthi bebas), **basis data nampung state** — dadi migration sing ngilangi kolom utawa ngobah data **ora bisa mung dibatalke** (data bisa ilang), nggawe perubahan destruktif iki beras tinggi utawa ora bisa dibatalke, lan sajroning rolling deployments **kode lawas lan anyar mlaku bareng**, loro-lorone kudu gawé karo schema ing saat kuwi.

Iki nggawe perubahan schema butuh koordinasi sing ati-ati, beda karo bagian CI/CD liyane.

Pamahaman babagan cara **ngotomasi migrations** (menehi katrangan minangka kode version nganggo tools kaya Flyway, Liquibase, utawa ORM migrations, njalanake minangka langkah pipeline sing diterapake kanthi urutan lan idempotent, lan nyoba ing staging dhisik) nggawe migrations dadi bagian saka automated pipeline kanthi aman.

Sing paling penting, pamahaman babagan **pola migration sing aman** — nggawe migrations **backward-compatible** supaya kode lawas lan anyar loro-lorone gawé sajroning transisi, nganggo **expand-contract pattern (parallel change)** (expand: tambahaké schema anyar tanpa ngrusak kode lawas; migrate: alihake kode lan isi maneh data; contract: ilangake schema lawas ing deploy sabanjure) lan **aja ngilangi/ngalangi alangngan bisa dikarepke ing deploy sing padha** — iki skill kunci sing ndadekake **zero-downtime deployments lan rollbacks sing aman** senadyan sifat stateful basis data.

Iki bener-bener angel, pengetahuan penting real-world sing mbedakake sing bisa deploy perubahan basis data kanthi aman saka sing nyebabake outages utawa kehilangan data.

Amarga database migrations minangka bagian angel, beras tinggi, ora bisa dihindari saka deploy aplikasi karo basis data, lan amarga nangani kanthi ati-ati (otomasi plus pola expand-contract backward-compatible) kaharusan kanggo deployments sing bisa dipercaya lan zero-downtime, pamahaman database migrations ing CI/CD minangka pengetahuan penting lan praksis — ngatasi salah sawijining aspek paling angel saka continuous delivery lan nggambaraké maturity sing dibutuhake kanggo deploy aplikasi stateful kanthi aman.