ExAws v2.1.0 ExAws View Source

ExAws

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A flexible easy to use set of AWS APIs.

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

Getting Started

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, "~> 2.0"},
    {: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

AWS Key configuration

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.

Hackney configuration

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

AWS Region Configuration.

You can set the region used by default for requests.

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

Direct Usage

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

—TODO—

Highlighted Features

  • 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!

Retries

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

License

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.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Link to this section Summary

Functions

Perform an AWS request

Perform an AWS request, raise if it fails

Return a stream for the AWS resource

Link to this section Functions

Link to this function request(op, config_overrides \\ []) View Source
request(ExAws.Operation.t, Keyword.t) ::
  {:ok, term} |
  {:error, term}

Perform an AWS request

First build an operation from one of the services, and then pass it to this function to perform it.

If you want to build an operation manually, see: ExAws.Operation

This function takes an optional second parameter of configuration overrides. This is useful if you want to have certain configuration changed on a per request basis.

Examples

If you have one of the service modules installed, you can just use those service modules like this:

ExAws.S3.list_buckets |> ExAws.request

ExAws.S3.list_buckets |> ExAws.request(region: "eu-west-1")

ExAws.Dynamo.get_object("users", "foo@bar.com") |> ExAws.request

Alternatively you can create operation structs manually for services that aren’t supported:

op = %ExAws.Operation.JSON{
  http_method: :post,
  service: :dynamodb,
  headers: [
    {"x-amz-target", "DynamoDB_20120810.ListTables"},
    {"content-type", "application/x-amz-json-1.0"}
  ],
}

ExAws.request(op)
Link to this function request!(op, config_overrides \\ []) View Source
request!(ExAws.Operation.t, Keyword.t) :: term | no_return

Perform an AWS request, raise if it fails.

Same as request/1,2 except it will either return the successful response from AWS or raise an exception.

Link to this function stream!(op, config_overrides \\ []) View Source

Return a stream for the AWS resource.

Examples

ExAws.S3.list_objects("my-bucket") |> ExAws.stream!