A flexible easy to use set of AWS APIs.

Available Services: https://github.com/ex-aws?q=service&type=&language=

ExAws v2.0 breaks out every service into its own package. To use the S3 service, you need both the core :ex_aws package as well as the :ex_aws_s3 package.

As with all ExAws services, you'll need a compatible HTTP client (defaults to :hackney) and whatever JSON or XML codecs needed by the services you want to use. Consult individual service documentation for details on what each service needs.

defp deps do
  [
    {:ex_aws, "~> 2.1"},
    {:ex_aws_s3, "~> 2.0"},
    {:hackney, "~> 1.9"},
    {:sweet_xml, "~> 0.6"},
  ]
end

With these deps you can use ExAws precisely as you're used to:

# make a request (with the default region)
ExAws.S3.list_objects("my-bucket") |> ExAws.request()

# or specify the region
ExAws.S3.list_objects("my-bucket") |> ExAws.request(region: "us-west-1")

# some operations support streaming
ExAws.S3.list_objects("my-bucket") |> ExAws.stream!() |> Enum.to_list()

ExAws requires valid AWS keys in order to work properly. ExAws by default does the equivalent of:

config :ex_aws,
  access_key_id: [{:system, "AWS_ACCESS_KEY_ID"}, :instance_role],
  secret_access_key: [{:system, "AWS_SECRET_ACCESS_KEY"}, :instance_role]

This means it will try to resolve credentials in order

• Look for the AWS standard AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables
• Resolve credentials with IAM
  • If running inside ECS and a task role has been assigned it will use it
  • Otherwise it will fall back to the instance role

AWS CLI config files are supported, but require an additional dependency:

{:configparser_ex, "~> 2.0"}

You can then add {:awscli, "profile_name", timeout} to the above config and it will pull information from ~/.aws/config and ~/.aws/credentials

config :ex_aws,
  access_key_id: [{:system, "AWS_ACCESS_KEY_ID"}, {:awscli, "default", 30}, :instance_role],
  secret_access_key: [{:system, "AWS_SECRET_ACCESS_KEY"}, {:awscli, "default", 30}, :instance_role]

For role based authentication via role_arn and source_profile an additional dependency is required:

{:ex_aws_sts, "~> 2.0"}

Further information on role based authentication is provided in said dependency.

ExAws by default uses hackney to make HTTP requests to AWS API. You can modify the options as such:

config :ex_aws, :hackney_opts,
  follow_redirect: true,
  recv_timeout: 30_000

You can set the region used by default for requests.

config :ex_aws,
  region: "us-west-2",

Alternatively, the region can be set in an environment variable:

config :ex_aws,
  region: {:system, "AWS_REGION"}

ExAws can also be used directly without any specific service module.

You need to figure out how the API of the specific AWS service works, in particular:

• Protocol (JSON or query).
• Path (depends on the service and the specific operation, usually "/").
• Service name (used to generate the request signature, as described here).
• Request body, query params, HTTP method, and headers (depends on the service and specific operation).

You can look for this information in the service's API reference at docs.aws.amazon.com or, for example, in the Go SDK API models at github.com/aws/aws-sdk-go (look for a api-*.json file).

The protocol dictates which operation module to use for the request. If the protocol is JSON, use ExAws.Operation.JSON, if it's query, use ExAws.Operation.Query.

action = :describe_clusters
action_string = action |> Atom.to_string |> Macro.camelize

operation =
  %ExAws.Operation.Query{
    path: "/",
    params: %{"Action" => action_string},
    service: :redshift,
    action: action
  }
  
ExAws.request(operation)

data = %{
  taskDefinition: "hello_world",
  launchType: "FARGATE",
  networkConfiguration: %{
    awsvpcConfiguration: %{
      subnets: ["subnet-1a2b3c4d", "subnet-4d3c2b1a"],
      securityGroups: ["sg-1a2b3c4d"],
      assignPublicIp: "ENABLED"
    }
  }
}

operation =
  %ExAws.Operation.JSON{
    http_method: :post,
    headers: [
      {"x-amz-target", "AmazonEC2ContainerServiceV20141113.RunTask"},
      {"content-type", "application/x-amz-json-1.1"}
    ],
    path: "/",
    data: data,
    service: :ecs
}

ExAws.request(operation)

• Easy configuration.
• Minimal dependencies. Choose your favorite JSON codec and HTTP client.
• Elixir streams to automatically retrieve paginated resources.
• Elixir protocols allow easy customization of Dynamo encoding / decoding.
• mix aws.kinesis.tail your-stream-name task for easily watching the contents of a kinesis stream.
• Simple. ExAws aims to provide a clear and consistent elixir wrapping around AWS APIs, not abstract them away entirely. For every action in a given AWS API there is a corresponding function within the appropriate module. Higher level abstractions like the aforementioned streams are in addition to and not instead of basic API calls.

That's it!

ExAws will retry failed AWS API requests using exponential backoff per the "Full Jitter" formula described in https://www.awsarchitectureblog.com/2015/03/backoff.html

The algorithm uses three values, which are configurable:

# default values shown below

config :ex_aws, :retries,
  max_attempts: 10,
  base_backoff_in_ms: 10,
  max_backoff_in_ms: 10_000

• max_attempts is the maximum number of possible attempts with backoffs in between each one
• base_backoff_in_ms corresponds to the base value described in the blog post
• max_backoff_in_ms corresponds to the cap value described in the blog post

If you want to run mix test, you'll need to have a local dynamodb running on port 8000.
See Setting up DynamoDB Local.

The redirect test will intentionally cause a warning to be issued.

The MIT License (MIT)

Copyright (c) 2014 CargoSense, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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