DiunDashboard/.planning/phases/03-postgresql-support/03-02-SUMMARY.md

phase, plan, subsystem, tags, dependency_graph, tech_stack, key_files, decisions, metrics

phase	plan	subsystem	tags	dependency_graph	tech_stack	key_files	decisions	metrics
03-postgresql-support	02	wiring	postgresql sqlite database docker-compose branching	requires provides affects 03-01 DATABASE_URL branching postgres docker profile NewTestPostgresServer cmd/diunwebhook/main.go compose.yml compose.dev.yml pkg/diunwebhook/diunwebhook.go	added patterns DATABASE_URL env var branching Docker Compose profiles build-tagged test helpers	created modified pkg/diunwebhook/postgres_test.go cmd/diunwebhook/main.go pkg/diunwebhook/diunwebhook.go compose.yml compose.dev.yml	DATABASE_URL present activates PostgreSQL path; absent falls back to SQLite with DB_PATH postgres Docker service uses profiles: [postgres] so default compose up remains SQLite-only UNIQUE detection uses strings.ToLower for case-insensitive matching across SQLite and PostgreSQL Build tag //go:build postgres gates postgres_test.go so standard test runs have no pgx dependency	duration completed tasks_completed files_changed ~2 minutes 2026-03-24T08:13:21Z 2 5

Phase 03 Plan 02: Wire PostgreSQL Support and Deployment Infrastructure Summary

DATABASE_URL branching in main.go routes to PostgresStore or SQLiteStore at startup; Docker Compose postgres profile enables optional PostgreSQL; build-tagged test helper and cross-dialect UNIQUE detection complete the integration.

What Was Built

Updated main.go (cmd/diunwebhook/main.go)

• DATABASE_URL env var check: when set, opens pgx connection, runs RunPostgresMigrations, creates NewPostgresStore, logs "Using PostgreSQL database"
• When absent: existing SQLite path using RunSQLiteMigrations (renamed in Plan 01), NewSQLiteStore, logs "Using SQLite database at {path}"
• Blank import _ "github.com/jackc/pgx/v5/stdlib" registers the "pgx" driver name
• All route wiring and graceful shutdown logic unchanged

Cross-dialect UNIQUE detection (pkg/diunwebhook/diunwebhook.go)

• TagsHandler now uses strings.Contains(strings.ToLower(err.Error()), "unique") for 409 Conflict detection
• SQLite errors: UNIQUE constraint failed: tags.name (uppercase UNIQUE)
• PostgreSQL errors: duplicate key value violates unique constraint "tags_name_key" (lowercase unique)
• Both backends now return 409 correctly

Docker Compose postgres profiles

• compose.yml: postgres service added with profiles: [postgres], healthcheck via pg_isready, DATABASE_URL env var in app service, conditional depends_on with required: false, postgres-data volume
• compose.dev.yml: same postgres service with port 5432 exposed on host for direct psql access during development
• Default docker compose up (no profile) unchanged — SQLite only, no new services start

Build-tagged test helper (pkg/diunwebhook/postgres_test.go)

• //go:build postgres tag — only compiled with go test -tags postgres
• NewTestPostgresServer() constructs a *Server backed by PostgreSQL using TEST_DATABASE_URL env var (defaults to postgres://diun:diun@localhost:5432/diundashboard_test?sslmode=disable)
• Calls RunPostgresMigrations and NewPostgresStore — mirrors the production startup path

Decisions Made

Decision	Rationale
DATABASE_URL presence-check (not a separate DB_DRIVER var)	Simpler UX; empty string = SQLite, any value = PostgreSQL
profiles: [postgres] in compose files	Standard Docker Compose pattern for optional services; default deploy unchanged
required: false in depends_on	App can start without postgres service (SQLite fallback); Docker Compose v2.20+ required
//go:build postgres tag on test helper	Prevents pgx import at test time for standard go test ./... runs; explicit opt-in
strings.ToLower for UNIQUE check	SQLite and PostgreSQL use different cases in constraint error messages

Deviations from Plan

None — plan executed exactly as written. The export_test.go rename (RunMigrations -> RunSQLiteMigrations) was already completed as a deviation in Plan 01, as noted in the objective.

Verification Results

• go build ./... exits 0
• go test -count=1 ./pkg/diunwebhook/ passes (all 20+ SQLite tests, postgres_test.go skipped)
• docker compose config validates without errors
• docker compose --profile postgres config shows postgres service
• grep -c "DATABASE_URL" cmd/diunwebhook/main.go returns 1
• grep "strings.ToLower" pkg/diunwebhook/diunwebhook.go shows case-insensitive UNIQUE check

Known Stubs

None — this plan wires implementation code, no UI stubs.

Self-Check: PASSED