aws-sigv4-sign

A small library for signing HTTP requests with AWS Signature Version 4 (SigV4) authentication, built with the official AWS SDK.

[!TIP] If you are using the fetch API, consider using the aws-sigv4-fetch package to automatically sign requests.

Install

npm install --save aws-sigv4-sign

ESM and CommonJS

This package ships with ES Module and CommonJS support. That means you can import or require the package in your project depending on your module format.

// ESM
import { signRequest } from 'aws-sigv4-sign';

// CommonJS
const { signRequest } = require('aws-sigv4-sign');

Usage

This package exports a signRequest function that returns a Request object with signed headers for AWS Signature V4 (SigV4) authentication. The function is overloaded with the same signature as the fetch API and an optional options parameter.

import { signRequest, SignRequestOptions } from 'aws-sigv4-sign';

const options: SignRequestOptions = {
  service: 'lambda',         // required
  region: 'eu-west-1',       // optional (defaults to 'us-east-1')
  credentials: {             // optional in Node.js (defaults to credentials from environment), required in browser
    accessKeyId: '...',
    secretAccessKey: '...',
    sessionToken: '...',
  }
};

const url = 'https://mylambda.lambda-url.eu-west-1.on.aws/';

// signRequest(input: string, options: SignRequestOptions)
const signedRequest = await signRequest(url, options);

// signRequest(input: URL, options: SignRequestOptions)
const signedRequest = await signRequest(new URL(url), options);

// signRequest(input: Request, options: SignRequestOptions)
const signedRequest = await signRequest(new Request(url), options);

// signRequest(input: string, init?: RequestInit, options: SignRequestOptions)
const signedRequest = await signRequest(url,
  {
    method: 'POST',
    body: JSON.stringify({ a: 1 }),
    headers: { 'Content-Type': 'application/json' }
  },
  options
);

The returned Request object contains the signed authorization headers with the following keys: authorization, host, x-amz-date, x-amz-content-sha256, x-amz-security-token (optional).

const signedRequest = await signRequest(url, options);

// Fetch the signed request
const response = await fetch(signedRequest);

// Log the signed headers from the request
console.log(signedRequest.headers.get('authorization')); // AWS4-HMAC-SHA256 Credential=.../20250101/us-east-1/lambda/aws4_request, SignedHeaders=host;x-amz-date;x-amz-content-sha256;x-amz-security-token, Signature=...
console.log(signedRequest.headers.get('host')); // mylambda.lambda-url.eu-west-1.on.aws
console.log(signedRequest.headers.get('x-amz-date')); // 20250101T000000Z
console.log(signedRequest.headers.get('x-amz-content-sha256')); // ...
console.log(signedRequest.headers.get('x-amz-security-token')); // only if credentials include a session token

// Convert the signed headers to plain object
const headers = Object.fromEntries(signedRequest.headers.entries());
console.log(headers.authorization); // AWS4-HMAC-SHA256 Credential=.../20250101/us-east-1/lambda/aws4_request, SignedHeaders=host;x-amz-date;x-amz-content-sha256;x-amz-security-token, Signature=...

The headers is a Headers object and can be converted to plain object for use with other HTTP libraries.

Options

The signRequest function accepts the following options:

Parameter	Type	Default	Description
service	string	Required	The service is required and must match the AWS service you are signing requests for. If it doesn't match, the request will fail with an error like: Credential should be scoped to correct service: 'service'.
region	string	us-east-1	The region is optional and defaults to us-east-1 if not provided. Some services like IAM are global and don't require a region.
credentials	AwsCredentialIdentity	Optional in Node.js, required in browser	The credentials is optional in Node.js environments where they will be retrieved from the environment using @aws-sdk/credential-provider-node. In browser environments, credentials are required and must be provided explicitly.

Credentials

The credentials have type AwsCredentialIdentity and consist of an accessKeyId, secretAccessKey and optionally a sessionToken. Credential handling differs between Node.js and browser environments:

Node.js

In Node.js environments, credentials are optional. If not provided, they will be automatically loaded from the environment using @aws-sdk/credential-provider-node, which checks several sources in this order:

• Environment variables exposed via process.env
• SSO credentials from token cache
• Web identity token credentials
• Shared credentials and config ini files
• The EC2/ECS Instance Metadata Service

Browser

In browser environments, credentials are required and must be provided explicitly for security reasons. The recommended method to provide credentials is to use Amazon Cognito Identity or web federated identity providers using @aws-sdk/credential-providers.

[!WARNING] Never hardcode AWS credentials in browser applications. Hard coding credentials poses a risk of exposing your access key ID and secret access key.

import { fromCognitoIdentity } from "@aws-sdk/credential-providers"

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', {
  service: 'lambda',
  region: 'eu-west-1',
  credentials: fromCognitoIdentity({
    // Required. The unique identifier for the identity against which credentials
    // will be issued.
    identityId: "us-east-1:128d0a74-c82f-4553-916d-90053example",
    // Optional. The ARN of the role to be assumed when multiple roles were received in the token
    // from the identity provider.
    customRoleArn: "arn:aws:iam::1234567890:role/MYAPP-CognitoIdentity",
    // Optional. A set of name-value pairs that map provider names to provider tokens.
    // Required when using identities associated with external identity providers such as Facebook.
    logins: {
      "graph.facebook.com": "FBTOKEN",
      "www.amazon.com": "AMAZONTOKEN",
      "accounts.google.com": "GOOGLETOKEN",
      "api.twitter.com": "TWITTERTOKEN'",
      "www.digits.com": "DIGITSTOKEN",
    },
    // Optional overrides. This is passed to an inner Cognito client
    // instantiated to resolve the credentials. Region and profile
    // are inherited from the upper client if present unless overridden.
    clientConfig: {},
  }),
});

Examples

The following examples show how to use the signed request with different HTTP libraries.

Fetch

import { signRequest } from "aws-sigv4-sign";

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', { service: 'lambda', region: 'eu-west-1' });
const response = await fetch(signedRequest);

Axios

import axios from "axios";
import { signRequest } from "aws-sigv4-sign";

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', { service: 'lambda', region: 'eu-west-1' });
const headers = Object.fromEntries(signedRequest.headers.entries());
const response = await axios(signedRequest.url, { headers });

Got

import { signRequest } from "aws-sigv4-sign";
import got from "got";

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', { service: 'lambda', region: 'eu-west-1' });
const headers = Object.fromEntries(signedRequest.headers.entries());
const response = await got(signedRequest.url, { headers });

Ky

import { signRequest } from "aws-sigv4-sign";
import ky from "ky";

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', { service: 'lambda', region: 'eu-west-1' });
const headers = Object.fromEntries(signedRequest.headers.entries());
const response = await ky.get(signedRequest.url, { headers });

node:https

import { signRequest } from "aws-sigv4-sign";
import { request } from "node:https";

const signedRequest = await signRequest('https://mylambda.lambda-url.eu-west-1.on.aws/', { service: 'lambda', region: 'eu-west-1' });
const headers = Object.fromEntries(signedRequest.headers.entries());
const body = "";
const response = new Promise((resolve, reject) => {
  const req = request(signedRequest.url, { headers }, (res) => {
    let data = "";

    res.on("data", (chunk) => {
      data += chunk;
    });

    res.on("end", () =>
      resolve({
        status: res.statusCode ?? 0,
        statusText: res.statusMessage,
        data,
      }),
    );
  });

  req.on("error", reject);

  if (body) {
    req.write(body);
  }

  req.end();
});

License

MIT