isabella232 / httpc-aws

A light-weight, relatively unopinionated AWS API client for Erlang

httpc-aws

A light-weight, relatively unopinionated AWS API client for Erlang 21.0+.

Supported Erlang Versions

• 21.0

Configuration

Configuration for httpc-aws is can be provided in multiple ways. It is designed to behave similarly to the AWS Command Line Interface with respect to providing region and configuration information. Additionally it has two methods, httpc_aws:set_region/1 and httpc_aws:set_credentials/2 to allow for application specific configuration, bypassing the automatic configuration behavior.

Configuration Precedence

The configuration values have the following precedence:

• Explicitly configured via API
• Environment variables
• Configuration file
• EC2 Instance Metadata Service where applicable

Credentials Precedence

The credentials values have the following precedence:

• Explicitly configured via API
• Environment variables
• Credentials file
• EC2 Instance Metadata Service

Environment Variables

As with the AWS CLI, the following environment variables can be used to provide configuration or to impact configuration behavior:

• AWS_DEFAULT_PROFILE
• AWS_DEFAULT_REGION
• AWS_CONFIG_FILE
• AWS_SHARED_CREDENTIALS_FILE
• AWS_ACCESS_KEY_ID
• AWS_SECRET_ACCESS_KEY

API Methods

Method	Description
httpc_aws:set_region/1	Manually specify the AWS region to make requests to.
httpc_aws:set_credentials/2	Manually specify the request credentials to use.
httpc_aws:refresh_credentials/0	Refresh the credentials from the environment, filesystem, or EC2 Instance Metadata service.
httpc_aws:get/2	Perform a GET request to the API specifying the service and request path.
httpc_aws:get/3	Perform a GET request specifying the service, path, and headers.
httpc_aws:post/4	Perform a POST request specifying the service, path, headers, and body.
httpc_aws:request/5	Perform a request specifying the service, method, path, headers, and body.
httpc_aws:request/6	Perform a request specifying the service, method, path, headers, body, and httpc:http_options().
httpc_aws:request/7	Perform a request specifying the service, method, path, headers, body, httpc:http_options(), and override the API endpoint.

Example Usage

The following example assumes that you either have locally configured credentials or that you're using the AWS Instance Metadata service for credentials:

application:start(httpc_aws).
{ok, {Headers, Response}} = httpc_aws:get("ec2","/?Action=DescribeTags&Version=2015-10-01").

To configure credentials, invoke httpc_aws:set_credentials/2:

application:start(httpc_aws).

httpc_aws:set_credentials("AKIDEXAMPLE", "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY"),

RequestHeaders = [{"Content-Type", "application/x-amz-json-1.0"},
                  {"X-Amz-Target", "DynamoDB_20120810.ListTables"}],

{ok, {Headers, Response}} = httpc_aws:post("dynamodb", "/",
                                           "{\"Limit\": 20}",
                                           RequestHeaders).

Build

$ bin/rebar3 compile

Test

$ bin/rebar3 eunit && bin/rebar3 eunit
$ bin/rebar3 dialyzer

License

BSD 3-Clause License