LAWS

A Lua library for interacting with AWS (Amazon Web Services).

Dependencies

• luaossl

Modules

aws.v4

Implements the AWS Signature v4 algorithm. This can be used to sign requests to a variety of Amazon services.

aws.v4.canonicalise_path

CanonicalURI = canonicalise_path(path)

Canonicalises the given string argument according to the v4 signature rules for paths:

• Removes redundant path components, e.g. .. and .
• Ensures (only) the correct characters are escaped

aws.v4.canonicalise_query_string

CanonicalQueryString = canonicalise_query_string(query)

Canonicalises the given string argument according to the v4 signature rules for query strings:

• Ensures (only) the correct characters are escaped
• Query arguments are sorted

aws.v4.derive_signing_key

kSigning = derive_signing_key(kSecret, Date, Region, Service)

Derives the signing key as specified in http://docs.aws.amazon.com/general/latest/gr/sigv4-calculate-signature.html Uses a SHA256 HMAC.

aws.v4.prepare_request

request, extra = prepare_request(tbl)

Prepares a signed HTTP(S) request.

Currently does not support Authentication parameters in the query string.

The fields of tbl are:

Field	Type	Description
.Domain	`string	nil`
.Region	string	The Amazon region. e.g. "us-east-1"
.Service	string	The Amazon service. e.g. "kinesis"
.method	string	e.g. "GET"
.CanonicalURI	`string	nil`
.path	`string	nil`
.CanonicalQueryString	`string	nil`
.query	`string	nil`
.headers	`{string:string	false}
.body	`string	nil`
.AccessKey	string	Your Amazon access key.
.SigningKey	`string	nil`
.SecretKey	`string	nil`
.timestamp	`number	nil`
.tls	`boolean	nil`
.port	`number	nil`

The returned request object has fields:

Field	Type	Description
.url	string	URL representing the Host,
.host	string	Host to connect to. e.g. "kinesis.us-east-1.amazonaws.com"
.port	number	TCP port to connect to. e.g. 443
.tls	boolean	Should SSL/TLS be used to connect? e.g. true
.method	string	e.g. "GET"
.target	string	The target (the part between method and HTTP/) ready to be used in a HTTP request. i.e. path and query string
.headers	{string:string}	Table of headers
.body	`string	nil`

The returned extra object has intermediary values calculated by the AWS v4 signing algorithm.

Field	Type
.CanonicalURI	string
.CanonicalQueryString	string
.SignedHeaders	string
.CanonicalHeaders	string
.CanonicalRequest	string
.StringToSign	string
.SigningKey	string
.Signature	string
.Authorization	string

If not provided, certain headers will be added. To prevent a header from getting added, provide it in .headers with a boolean value of false

• Host
• X-Amz-Date
• Authorization

Example

This example prepares a HTTP request to Amazon Kinesis to ListStreams

local prepare_request = require "aws.v4".prepare_request
local request, extra = prepare_request {
	Region = "us-east-1";
	Service = "kinesis";
	method = "POST";
	headers = {
		["X-Amz-Target"] = "Kinesis_20131202.ListStreams";
		["Content-Type"] = "application/x-amz-json-1.1";
	};
	body = '{}';
	AccessKey = "AKIDEXAMPLE";
	SecretKey = "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY";
}