add example pg_backup.sh script

pg_backup.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+
+set -e
+
+BACKUP_FILE='/var/lib/postgresql/data/backup.sql'
+
+function backup {
+  export PGPASSWORD=$(cat $POSTGRES_PASSWORD_FILE)
+  pg_dump -U ${POSTGRES_USER} ${POSTGRES_DB} > $BACKUP_FILE
+}
+
+function restore {
+    cd /var/lib/postgresql/data/
+    restore_config(){
+        # Restore allowed connections
+        cat pg_hba.conf.bak > pg_hba.conf
+        su postgres -c 'pg_ctl reload'
+    }
+    # Don't allow any other connections than local
+    cp pg_hba.conf pg_hba.conf.bak
+    echo "local all all trust" > pg_hba.conf
+    su postgres -c 'pg_ctl reload'
+    trap restore_config EXIT INT TERM
+
+    # Recreate Database
+    psql -U ${POSTGRES_USER} -d postgres -c "DROP DATABASE ${POSTGRES_DB} WITH (FORCE);" 
+    createdb -U ${POSTGRES_USER} ${POSTGRES_DB}
+    psql -U ${POSTGRES_USER} -d ${POSTGRES_DB} -1 -f $BACKUP_FILE
+
+    trap - EXIT INT TERM
+    restore_config
+}
+
+$@