008: personal database iwanhae owned by admin role

README.md

@@ -48,6 +48,7 @@ For a private repo you need an auth strategy:
 | 005 | mount-pgdata               | /dev/sdb (20G) -> /var/lib/postgresql, fstab  |
 | 006 | install-postgres           | PG 18 via PGDG repo, cluster on the disk     |
 | 007 | postgres-admin-role        | iwanhae OS user -> PG superuser (peer auth)  |
+| 008 | create-db-iwanhae          | database `iwanhae` owned by admin role       |
 
 ## Roadmap
 

migrations/008-create-db-iwanhae.sh

@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+# 008-create-db-iwanhae - Create the personal database `iwanhae` owned by
+# the admin role from 007, so plain `psql` works without -d.
+# up:   CREATE DATABASE iwanhae OWNER iwanhae (skip if it already exists)
+# down: DROP DATABASE - refuses while it contains user objects (data safety)
+set -euo pipefail
+
+DB=iwanhae
+ROLE=iwanhae
+
+db_exists() {
+  runuser -u postgres -- psql -v ON_ERROR_STOP=1 -tAc \
+    "SELECT 1 FROM pg_database WHERE datname='$DB'" | grep -q 1
+}
+
+user_object_count() {
+  runuser -u postgres -- psql -v ON_ERROR_STOP=1 -d "$DB" -tAc \
+    "SELECT count(*) FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace
+      WHERE n.nspname NOT IN ('pg_catalog', 'information_schema')
+        AND c.relkind IN ('r', 'p', 'v', 'm', 'S', 'f')" | tr -d ' '
+}
+
+case "${1:-}" in
+  up)
+    if db_exists; then
+      echo "    database $DB already exists - skipping"
+    else
+      runuser -u postgres -- psql -v ON_ERROR_STOP=1 -qc \
+        "CREATE DATABASE $DB OWNER $ROLE"
+      echo "    database $DB created, owner $ROLE"
+    fi
+    ;;
+  down)
+    if ! db_exists; then
+      echo "    database $DB does not exist - nothing to do"
+      exit 0
+    fi
+    if [[ $(user_object_count) -gt 0 ]]; then
+      echo "refusing to drop $DB - it contains user objects (data would be lost)" >&2
+      echo "drop it manually if you really want: runuser -u postgres -- psql -c 'DROP DATABASE $DB WITH (FORCE)'" >&2
+      exit 1
+    fi
+    runuser -u postgres -- psql -v ON_ERROR_STOP=1 -qc \
+      "DROP DATABASE $DB WITH (FORCE)"   # FORCE: kick lingering psql sessions
+    echo "    database $DB dropped (was empty)"
+    ;;
+esac