Export PG* envs when restoring postgres from backup

{{cookiecutter.project_slug}}/compose/production/postgres/maintenance/restore

@@ -37,7 +37,10 @@ if [[ "${POSTGRES_USER}" == "postgres" ]]; then
     exit 1
 fi
 
+export PGHOST="postgres"
+export PGUSER="${POSTGRES_USER}"
 export PGPASSWORD="${POSTGRES_PASSWORD}"
+export PGDATABASE="${POSTGRES_DB}"
 
 message_info "Dropping all connections to the database..."
 # Source: http://dba.stackexchange.com/a/11895
@@ -54,23 +57,12 @@ psql \
     --command="${drop_postgres_connections_sql}"
 
 message_info "Dropping the database..."
-dropdb \
-    --host=postgres \
-    --username="${POSTGRES_USER}" \
-    "${POSTGRES_DB}"
+dropdb "${PGDATABASE}"
 
 message_info "Creating a new database..."
-createdb \
-    --host=postgres \
-    --username="${POSTGRES_USER}" \
-    --owner="${POSTGRES_USER}" \
-    "${POSTGRES_DB}"
+createdb --owner="${POSTGRES_USER}"
 
 message_info "Applying the backup to the new database..."
-gunzip -c "${backup_filename}" \
-    | psql \
-        --host=postgres \
-        --username="${POSTGRES_USER}" \
-        "${POSTGRES_DB}"
+gunzip -c "${backup_filename}" | psql "${POSTGRES_DB}"
 
 message_success "The '${POSTGRES_DB}' database has been restored from the '${backup_filename}' backup."