PostgreSQL node example (#26)

Add a function to perform a query on a PostgreSQL database using Node.
---------
Co-authored-by: Thomas TACQUET <thomas@tacquet.net>
Co-authored-by: Andy Méry <amery@scaleway.com>

Author: 3 people

README.md

@@ -42,6 +42,7 @@ Table of Contents:
 | **[Redis TLS](functions/redis-tls/README.md)** <br/> How to connect a function to a Scaleway Redis cluster with TLS enabled.                       | python310 | [Serverless Framework] |
 | **[Rust MNIST](functions/rust-mnist/README.md)** <br/> A Rust function to recognize hand-written digits with a simple neural network.              | rust165   | [Serverless Framework] |
 | **[Terraform Python](functions/terraform-python-example/README.md)** <br/> A Python function deployed with Terraform.                              | python310 | [Terraform]            |
+| **[PostgeSQL Node](functions/postgre-sql-node/README.md)** <br/> A Node function to connect and interact with PostgreSQL database.                 | node18    | [Serverless Framework]         |
 
 ### 📦 Containers
 

functions/postgre-sql-node/README.md

@@ -0,0 +1,60 @@
+# Interact with a PostgreSQL database using functions
+
+## Requirements
+
+This example assumes that you are familiar with some products of Scaleway's ecosystem: 
+ * how serverless functions work. If needed, you can check [Scaleway official documentation](https://www.scaleway.com/en/docs/serverless/functions/quickstart/).
+ * how a managed database for PostgreSQL works, and especially how to create a database and create users with appropriate permissions. Please refer to scaleway's documentation [here](https://www.scaleway.com/en/docs/managed-databases/postgresql-and-mysql/quickstart/).
+
+This example uses the Scaleway Serverless Framework Plugin. Please set up your environment with the requirements stated in the [Scaleway Serverless Framework Plugin](https://github.com/scaleway/serverless-scaleway-functions) before trying out the example.
+
+
+## Context
+
+This example shows how to connect to a managed PostgreSQL database and perform a query on it. This example can be extended to adding, deleting, or processing data within a database.
+
+
+## Description
+
+The function connects to a PostgreSQL database and performs an example query on it. This example uses Node 18 runtime. Used packages are specified in `package.json`.
+
+## Setup
+
+### Create a managed PostgreSQL database 
+
+Create a PostgreSQL database and a user profile with appropriate access permissions.
+
+### Fill environment variables
+
+Fill your secrets within `serverless.yml` file:
+
+```
+secret:
+    PG_HOST: "your host IP address"
+    PG_USER: "your database username"
+    PG_DATABASE: "your database name"
+    PG_PASSWORD: "your databse user password"
+    PG_PORT: "your database port"
+```
+
+### Install npm modules
+
+Once your environment is set up, you can install `npm` dependencies from `package.json` file using:
+
+```
+npm install
+```
+
+### Deploy and call the function
+
+Then deploy your function and get its URL using:
+
+```
+serverless deploy
+```
+
+From the given function URL, you can run your function using:
+
+```
+curl <function URL>
+```

functions/postgre-sql-node/handler.js

@@ -0,0 +1,53 @@
+const pg = require('pg')
+
+const PG_HOST=process.env.PG_HOST;
+const PG_USER=process.env.PG_USER;
+const PG_DATABASE=process.env.PG_DATABASE;
+const PG_PASSWORD=process.env.PG_PASSWORD;
+const PG_PORT=parseInt(process.env.PG_PORT,10);
+
+const pool = new pg.Pool({
+  user: PG_USER,
+  host: PG_HOST,
+  database: PG_DATABASE,
+  password: PG_PASSWORD,
+  port: PG_PORT
+})
+
+exports.handle = async (event, context, callback) => {
+  try {
+      const { rows } = await query("SELECT * FROM table LIMIT 10")
+      console.log(JSON.stringify(rows[0]))
+      const response = {
+          "statusCode": 200,
+          "headers": {
+              "Content-Type" : "application/json"
+          },
+          "body": JSON.stringify(rows),
+          "isBase64Encoded": false
+      };
+      callback(null, response);
+  } catch (err) {
+      console.log('Database ' + err)
+      callback(err);
+  }
+  };
+
+async function query (q) {
+  const client = await pool.connect()
+  let res
+  try {
+    await client.query('BEGIN')
+    try {
+      res = await client.query(q)
+      await client.query('COMMIT')
+    } catch (err) {
+      await client.query('ROLLBACK')
+      throw err
+    }
+  } finally {
+    client.release()
+  }
+
+  return res
+}

functions/postgre-sql-node/package.json

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+{
+  "name": "postgreSQL-node-example",
+  "version": "1.0.0",
+  "main": "handler.js",
+  "type": "commonjs",
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "pg": "^8.10.0"
+  },
+  "devDependencies": {
+    "serverless-scaleway-functions": "^0.4.6"
+  }
+}

functions/postgre-sql-node/serverless.yml

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+service: scaleway-node18
+configValidationMode: off
+singleSource: false
+provider:
+  name: scaleway
+  runtime: node18
+
+  secret:
+    PG_HOST: "your host IP address"
+    PG_USER: "your database username"
+    PG_DATABASE: "your database name"
+    PG_PASSWORD: "your databse user password"
+    PG_PORT: "your database port"
+
+plugins:
+  - serverless-scaleway-functions
+
+package:
+  patterns:
+    - '!.gitignore'
+    - '!.git/**'
+
+functions:
+ get-all-from-table
+    handler: handler.handle