use DATABASE_URL for node api

05-example-web-application/api-node/Makefile

@@ -1,10 +1,6 @@
 .PHONY: run-local
 run-local:
-	PGUSER=postgres \
-    PGHOST=localhost \
-    PGPASSWORD=foobarbaz \
-    PGDATABASE=postgres \
-    PGPORT=5432 \
+	DATABASE_URL=postgres://postgres:foobarbaz@localhost:5432/postgres \
     node ./src/index.js
 
 .PHONY: build-naive

05-example-web-application/api-node/src/db.js

@@ -1,6 +1,8 @@
 const { Pool } = require('pg');
 
-const pool = new Pool();
+const pool = new Pool({
+  connectionString: process.env.DATABASE_URL,
+});
 
 // the pool will emit an error on behalf of any idle clients
 // it contains if a backend error or network partition happens