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Code examples for Serverless Functions

Reviewed on 12 July 2023Published on 18 October 2021

This page shows examples of functions in Python, Node, Golang, PHP, and Rust that can be used in your Serverless Functions projects.

Tip:

You can find many more advanced examples and real-life use cases using Serverless products in our Serverless Examples repository.

Requirements:

Python

Returning a function result in Python

There are several ways to return a response from a handler function:

Response object with HTTP information:

def handle(event, context):
return {
"body": {
"message": "hello world"
},
"statusCode": 200,
"headers": {
"Content-Type": ["application/json"],
"your-header": "your-value"
}
}

Straight response without body:

def handle(event, context):
return {"message": "hello world"}
# or
return "my Message"

Stringified response body (AWS Lambda):

import json
def handle(event, context):
return {
"body": json.dumps({"message": "hello world"}),
"headers": {
"Content-Type": ["application/json"],
},
"statusCode": 200,
}

Getting data in Python

Using environment variables

Python runtime includes the os, which enables you to access the environment variables you define in your namespaces or functions.

The following snippet returns the environment variable ENV you specified in the function or namespace configuration:

import os
def handle(event, context):
env_variable = os.getenv('ENV')
return env_variable

Using event objects in Python

You can pass information through your HTTP request with event objects. They are composed of the following objects:

  • path: str - Parameters defined in the path of the HTTP request
  • queryStringParameters: dict[str, str] - Query Strings parameters of the HTTP request
  • body: str - Body of the HTTP request, you will have to parse it in your handler to use it properly.
  • headers: dict[str, str] - HTTP request headers
  • method: string - HTTP method used
  • isBase64Encoded: boolean - Whether the request body is base64 encoded.
def handle(event, context):
# the event object is a Python dict
query_param = event['queryStringParameters']['parameter']
query_body = event['body']
# ...

Example of reading URL parameters:

curl https://myfunc/user/?id=1

Will fill the event with following parameters:

event['path'] = "/user/"
event['queryStringParameters'] = {
"id": "1"
}

Using data from CRON jobs in Python

CRON jobs share the same pattern as HTTP calls. You can find the information passed into the CRON body in the event object:

def handle(event, context):
cron_body = event['body']
# ...

Connecting to HTTP services in Python

You might need to get information or transmit data to an external service. The Scaleway python runtime includes the urllib library which enables you to connect to HTTP services without adding external libraries.

Refer to our guide on code packaging if you want to use requests.

GET request example

from urllib import request, parse, error
import os
auth_token=os.getenv('X-AUTH-TOKEN') # you can pass token through os environment variable or secret environment variable
url={YOUR URL} # if you want a dynamic url based on informations sent to handle(), please define the url inside the function
def handle(event, context):
req = request.Request(url, method='GET')
req.add_header('X-Auth-Token',auth_token)
try:
res = request.urlopen(req).read().decode()
except error.HTTPError as e:
res = e.read().decode()
return {
"body": json.loads(res),
"headers": {
"Content-Type": ["application/json"],
},
"statusCode": 200,
}

POST request example

from urllib import request, parse, error
import os
auth_token=os.getenv('X-AUTH-TOKEN') # you can pass token through os environment variable or secret environment variable
url={YOUR URL} # if you want a dynamic url based on information sent to handle(), please define the url inside the function
def handle(event, context):
data=json.dumps({"sample_key": "sample_value"}).encode('ascii')
req = request.Request(url, data=data, method="POST")
req.add_header('Content-Type', 'application/json')
req.add_header('X-Auth-Token', auth_token)
# Sending request to Instance API
try:
res=request.urlopen(req).read().decode()
except error.HTTPError as e:
res=e.read().decode()
return {
"body": json.loads(res),
"headers": {
"Content-Type": ["application/json"],
},
"statusCode": 200,
}
try:
res = request.urlopen(req).read().decode()
except error.HTTPError as e:
res = e.read().decode()
return {
"body": json.loads(res),
"headers": {
"Content-Type": ["application/json"],
},
"statusCode": 200,
}
Note:

To use other libraries like request, you need to upload your project with advanced methods (recommended) or using a ZIP file.

Advanced Python examples

To find advanced and real world examples for Functions, take a look at our dedicated repository: github.com/scaleway/serverless-examples

Node

Returning a function result in Node

Note:

The following examples use CommonJS modules. If you use ES modules refer to the dedicated section of this documentation.

There are multiple ways a response can return from a handler function:

  • With body and statusCode. This response type sets the status code as HTTP Response Code, and body as the response’s body, headers as Headers.

Stringified body (like AWS Lambda):

module.exports.myHandler = (event, context, callback) => {
return {
statusCode: 201,
body: JSON.stringify({
message: "async function",
}),
headers: {
"Content-Type": "application/json",
},
}
}

Not Stringified body (like AWS Lambda):

module.exports.myHandler = (event, context, callback) => {
return {
statusCode: 201,
body: {
message: "async function",
},
headers: {
"Content-Type": "application/json",
},
}
}
  • With object/entity (number, boolean, string…) without properties body and statusCode
module.exports.myHandler = (event, context, callback) => {
return {
body: "message",
headers: {
"Content-Type": ["text/plain"],
},
};
// Or
return JSON.stringify({ message: "message" });
// OR
return "Hello, world";
// OR
return 1; // true, false, undefined, null...
};

Using the callback parameter:

module.exports.myHandler = (event, context, callback) => {
const response = {
statusCode: 201,
body: {
message: "async function",
},
headers: {
"Content-Type": "application/json",
},
};
// Successful response
callback(undefined, response);
// Error response
callback(new Error("something bad happened..."));
};
  • With a Promise:
module.exports.myHandler = async (event, context, callback) => {
return {
statusCode: 201,
body: {
message: "async function",
},
headers: {
"Content-Type": "application/json",
},
};
}
// OR
module.exports.myHandler = (event, context, callback) => {
const response = {
statusCode: 201,
body: {
message: "async function",
},
headers: {
"Content-Type": "application/json",
},
};
return new Promise((resolve, reject) => {
// do something
if (err) return reject(err);
return resolve(response);
});
};

Using environment variables in Node

If you need to pass information to your function you can use environment variables defined at the namespace or function level. In JavaScript they are stored in the process.env object:

module.exports.myHandler = (event, context, callback) => {
const myParameter = process.env.MYPARAMETER;
return {
statusCode: 201,
body: JSON.stringify({
parameter: myParameter,
}),
headers: {
"Content-Type": "application/json",
},
}
}

Using event components

You can pass information through your HTTP request with the event object. It is composed of the following objects:

  • path: string - Parameters defined in the path of the HTTP request
  • queryStringParameters: object - Query Strings parameters of the HTTP request
  • body: string - Body of the HTTP request, you will have to parse it in your handler to use it properly
  • headers: object - HTTP request headers
  • httpMethod: string - HTTP method used
  • isBase64Encoded: boolean - Whether the request body is base64 encoded
module.exports.myHandler = (event, context, callback) => {
const queryStringParameters = event.queryStringParameters;
const body = event.body;
// ...
};

Example of reading URL parameters:

curl https://myfunc/user/?id=1

Will fill the event with following parameters:

event.path = "/user/"
event.queryStringParameters = {
"id": "1"
}

Using data from CRON jobs in Node

CRON jobs share the same pattern as HTTP calls. You will find the information passed into the CRON body in the event object:

module.exports.myHandler = (event, context, callback) => {
body = event.body;
return {
statusCode: 201,
body: JSON.stringify({
body: body,
}),
headers: {
"Content-Type": "application/json",
},
};
};

Connecting to HTTP services in Node

You might need to get information or transmit data to an external service. The following code snippets can be executed directly in Serverless Functions without adding external libraries.

Refer to our guide on code packaging, if you want to use fetch, axios, …

GET request sample:

const https = require("https");
exports.handle = async function (event, context) {
let dataString = "";
const response = await new Promise((resolve, reject) => {
const req = https.get(
"https://pokeapi.co/api/v2/pokemon/ditto",
function (res) {
res.on("data", (chunk) => {
dataString += chunk;
});
res.on("end", () => {
resolve({
statusCode: 200,
headers: { "Content-Type": ["application/json"] },
body: JSON.stringify(JSON.parse(dataString), null, 4),
});
});
}
);
req.on("error", (e) => {
reject({
statusCode: 500,
body: "Something went wrong!",
});
});
});
return response;
};

POST request sample

const https = require("https");
exports.handle = async function (event, context) {
let dataString = "";
const postData = JSON.stringify({
name: "John Doe",
email: "jdoe@scaleway.com",
});
const options = {
hostname: "postman-echo.com",
path: "/post",
method: "POST",
headers: {
"Content-Type": "application/json",
},
};
const response = await new Promise((resolve, reject) => {
const req = https.request(options, (res) => {
res.on("data", (chunk) => {
dataString += chunk;
});
res.on("end", () => {
resolve({
statusCode: 200,
headers: { "Content-Type": ["application/json"] },
body: JSON.stringify(JSON.parse(dataString), null, 4),
});
});
res.on("error", (e) => {
reject({
statusCode: 500,
body: "Something went wrong!",
});
});
});
// write data to request body
req.write(postData);
req.end();
});
return response;
};

Using ES Modules

Node has two module systems: CommonJS modules and ECMAScript (ES) modules. By default, Node treats your code files as CommonJS modules, however ES modules are also available on Scaleway Serverless Functions. ES modules give you a more modern way to reuse your code.

According to the official documentation, you can specify the module type in package.json to use ES modules, as in the following example:

...
"type": "module",
...

This then enables you to write your code for ES modules:

export { handle };
function handle(event, context, cb) {
return {
body: process.version,
headers: { "Content-Type": ["text/plain"] },
statusCode: 200,
};
}

The use of ES modules is encouraged, since they are more efficient and make setup and debugging much easier.

Using "type": "module" or "type": "commonjs" in your package.json file will enable/disable some features in Node runtime. For a comprehensive list of differences, refer to the official documentation, the following is a summary only:

  • commonjs is used as default value
  • commonjs allows you to use require/module.exports (synchronous code loading that copies all file contents)
  • module allows you to use import/export ES6 instructions (optimized asynchronous loading that imports only the pieces of code you need)

Advanced NodeJS examples

Check out our dedicated examples repository for advanced examples and real-life use cases using Serverless products.

Go

Requirements:
  • your code must be a valid Go module: a go.mod file is expected in the root directory (ex: go mod init myhandler)
  • handler function must be in a file at the root of your module
  • handler must be exported: Handle is correct, but handle is not because it is not exported
  • handler must have the following signature: func HandlerName(w http.ResponseWriter, r *http.Request)
  • handler cannot be in the main package

Suggested layout:

.
├── go.mod # your go.mod defines your module
├── go.sum # not always necessary
├── myfunc.go # your exported handler must be defined here
└── subpackage # you can have subpackages
└── hello.go # with files inside

Hello world in Go

package myfunc
import (
"encoding/json"
"net/http"
)
// Handle - Handle event
func Handle(w http.ResponseWriter, r *http.Request) {
response := map[string]interface{}{
"message": "We're all good",
"healthy": true,
"number": 4,
}
responseB, err := json.Marshal(response)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "application/json")
_, _ = w.Write(responseB)
}

Using r *http.Request object, you can get the method, the headers, the body, etc, as if you were using a simple http server.

You must use the w http.ResponseWriter parameter to send a response to the function caller.

Using environment variables in Go

You can use environment variables defined at the Namespace or Function level to pass information to your function:

In the following code snippet, we use environment variables to get Database configuration information:

package myfunc
import (
"fmt"
"log"
"os"
)
func Handle(w http.ResponseWriter, r *http.Request) {
// For example, get Database configuration from environment variables
dbName := os.Getenv("DB_NAME")
dbUser := os.Getenv("DB_USER")
dbPassword := os.Getenv("DB_PASSWORD")
dbHost := os.Getenv("DB_HOST")
dbPort := os.Getenv("DB_PORT")
connectionString := fmt.Sprintf("%s:%s@%s:%s/%s", dbUser, dbPassword, dbHost, dbPort, dbName)
// Your code to use the database...
// Technically it's not recommended to add database connections or other resource initialization
// in function handler because it will be called each time a function is triggered.
}

Read request content

Using net/http/httputil can help to dump request content.

package myfunc
import (
"fmt"
"net/http"
"net/http/httputil"
)
// Handle - Handle event
func Handle(w http.ResponseWriter, r *http.Request) {
dump, _ := httputil.DumpRequest(r, true)
fmt.Fprintf(w, "%s\n", string(dump))
}

Read URL Parameters in Go

package myfunc
import (
"encoding/json"
"net/http"
)
// This handler will dump all URL parameters.
func Handle(w http.ResponseWriter, r *http.Request) {
res, _ := json.Marshal(r.URL)
w.Write(res)
}

Example of reading URL parameters:

curl https://myfunc/user/?id=1

Will fill the event with following parameters:

r.URL.Path = "/user/"
r.URL.RawQuery = "id=1"

Connecting to HTTP services in Go

** GET request example**

package myfunc
import (
"io"
"net/http"
)
func Handle(w http.ResponseWriter, r *http.Request) {
req, err := http.Get("https://jsonplaceholder.typicode.com/posts")
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
body, err := io.ReadAll(r.Body)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
w.Write([]byte(body))
}

Testing your Go function locally

Local development makes it easier to write, test, and debug, as well as making it faster to call your function.

You can find our Go library here.

Advanced Go examples

Check out our dedicated examples repository for advanced examples and real-life use cases using Serverless products.

Rust

Hello world in Rust

use hyper::{
Body, Request, Response, StatusCode,
};
pub async fn handle(_req: Request<Body>) -> Response<Body> {
Response::builder()
.status(StatusCode::OK)
.header("Content-type", "text/plain")
.body(Body::from("Hello from rust"))
.unwrap()
}

Advanced Rust examples

Check our dedicated examples repository for advanced examples and real-life use cases using Serverless products.

PHP

PHP runtime supports composer dependency management. Adding composer.json in your project will automatically fetch the required dependencies.

Returning a function result in PHP

Response object with HTTP information:

<?php
function handle($event, $context)
{
return [
"body" => "Hello from php",
"statusCode" => 200,
];
}

Getting data in PHP

Using environment variables

PHP runtime includes the getenv function, which enables you to access the environment variables you define in your namespaces or functions. The following snippet returns the environment variable ENV you specified in the function or namespace configuration:

<?php
function handle($event, $context)
{
$env = getenv("ENV");
return [
"body" => $env,
"statusCode" => 200,
];
}

Using event objects in PHP

You can pass information through your HTTP request with event objects. They are composed of the following objects:

  • path: string - Parameters defined in the path of the HTTP request
  • queryStringParameters: map(string)string - Query Strings parameters of the HTTP request
  • body: string - Body of the HTTP request, you will have to parse it in your handler to use it properly.
  • headers: map(string)string - HTTP request headers
  • method: string - HTTP method used
  • isBase64Encoded: boolean - Whether the request body is base64 encoded.
<?php
function handle($event, $context) {
$queryparameter = $event["queryStringParameters"]["parameter"];
$querybody = $event["body"];
return [
"body" => $querybody,
"statusCode" => 200,
];
}

Example of reading URL parameters:

curl https://myfunc/user/?id=1

Will fill the event with following parameters:

$event['path'] = "/user/"
$event['queryStringParameters'] = {
"id": "1"
}

Using data from CRON jobs in PHP

CRON jobs share the same pattern as HTTP calls. You can find the information passed into the CRON body in the event object:

<?php
function handle($event, $context) {
$cronbody = $event["body"];
return [
"body" => $cronbody,
"statusCode" => 200,
];
}

Advanced PHP examples

Check our dedicated examples repository for advanced examples and real-life use cases using Serverless products.