feat(functions): PostgreSQL Python example (#28)

Add example of pythonic serverless function to connect and perform a query on PostgreSQL database.

Author: redanrd

README.md

@@ -41,6 +41,7 @@ Table of Contents:
 | **[Python Dependencies](functions/python-dependencies/README.md)** <br/> Example showing how to use Python requirements with Serverless Framework. | python310 | [Serverless Framework] |
 | **[Redis TLS](functions/redis-tls/README.md)** <br/> How to connect a function to a Scaleway Redis cluster with TLS enabled.                       | python310 | [Terraform]            |
 | **[Rust MNIST](functions/rust-mnist/README.md)** <br/> A Rust function to recognize hand-written digits with a simple neural network.              | rust165   | [Serverless Framework] |
+| **[PostgreSQL Python](functions/postgre-sql-python/README.md)** <br/> A Python function to perform a query on a PostgreSQL managed database.       | python310 | [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]         |
 

functions/postgre-sql-python/README.md

@@ -0,0 +1,61 @@
+# Interact with a PostgreSQL database using pythonic 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 Python 3.10 runtime. Used packages are specified in `package.json`. As a requirement for this example we use a pre-compiled [`psycopg2` version](https://www.psycopg.org/docs/install.html#install-from-source).
+
+## 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 database user password"
+    PG_PORT: "your database port"
+    PG_SSL_ROOT_CERT: "path to your database ssl certificate"
+```
+
+### 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:
+
+```
+./bin/deploy.sh
+```
+
+From the given function URL, you can run your function using:
+
+```
+curl <function URL>
+```

functions/postgre-sql-python/bin/deploy.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+set -e
+
+./bin/deps.sh
+
+serverless deploy

functions/postgre-sql-python/bin/deps.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -e
+
+# This command will run pip install with the given requirements.txt file inside
+# a docker container compatible with our function runtimes, and pull the installed
+# dependencies locally to your package directory. As these dependencies have been
+# installed on top of alpine Linux with our compatible system libraries, you will
+# be able to upload your source code and deploy your function properly.
+PYTHON_VERSION=3.10
+docker run --rm -v $(pwd):/home/app/function --workdir /home/app/function rg.fr-par.scw.cloud/scwfunctionsruntimes-public/python-dep:$PYTHON_VERSION pip install -r ./requirements.txt --target ./package

functions/postgre-sql-python/handlers/handler.py

@@ -0,0 +1,56 @@
+import psycopg2
+from psycopg2 import Error
+import os
+import logging
+
+PG_HOST=os.environ.get('PG_HOST')
+PG_USER=os.environ.get('PG_USER')
+PG_DATABASE=os.environ.get('PG_DATABASE')
+PG_PASSWORD=os.environ.get('PG_PASSWORD')
+PG_PORT=os.environ.get('PG_PORT')
+PG_SSL_ROOT_CERT=os.environ.get('PG_SSL_ROOT_CERT')
+
+def handle(event, context):
+
+    try:
+        connection = psycopg2.connect(
+            database=PG_DATABASE,
+            user=PG_USER,
+            host=PG_HOST,
+            password=PG_PASSWORD,
+            port=PG_PORT,
+            sslmode="require",
+            sslrootcert=PG_SSL_ROOT_CERT,
+            )
+
+    except (Exception, Error) as error:
+        logging.error("Error while connecting to PostgreSQL database", error)
+        return {
+                "statusCode": 500,
+                "body": {
+                    "message": "Error while connecting to PostgreSQL database, check function logs for more information"
+                }
+        }
+
+    try:
+        cursor = connection.cursor()
+        logging.info("Connected to Database")
+        cursor.execute("SELECT * FROM table LIMIT 10")
+        record = cursor.fetchone()
+        logging.info("Successfully fetched data")
+        cursor.close()
+        return {
+                "statusCode": 200,
+                "body": {
+                    "message": record
+                }
+        }
+
+    except (Exception, Error) as error:
+        logging.error("Error while interacting with PostgreSQL", error)
+        return {
+                "statusCode": 500,
+                "body": {
+                    "message": "Error while getting information from PostgreSQL database, check function logs for more information"
+                }
+        }

functions/postgre-sql-python/package.json

@@ -0,0 +1,5 @@
+{
+  "devDependencies": {
+    "serverless-scaleway-functions": "^0.4.6"
+  }
+}

functions/postgre-sql-python/requirements.txt

@@ -0,0 +1 @@
+psycopg2-binary == 2.9

functions/postgre-sql-python/serverless.yml

@@ -0,0 +1,27 @@
+service: get-all-from-database
+
+configValidationMode: off
+
+provider:
+  name: scaleway
+  runtime: python310
+  secret:
+    PG_HOST: "your database host IP address"
+    PG_USER: "your database username"
+    PG_DATABASE: "your database name"
+    PG_PASSWORD: "your database user password"
+    PG_PORT: "your database port"
+    PG_SSL_ROOT_CERT: "path to your database ssl certificate"
+
+plugins:
+  - serverless-scaleway-functions
+
+package:
+  patterns:
+    - '!node_modules/**'
+    - '!.gitignore'
+    - '!.git/**'
+
+functions:
+  first:
+    handler: handlers/handler.handle