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https://github.com/erlcloud/erlcloud

AWS APIs library for Erlang (Amazon EC2, S3, SQS, DDB, ELB and etc)
https://github.com/erlcloud/erlcloud

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AWS APIs library for Erlang (Amazon EC2, S3, SQS, DDB, ELB and etc)

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# erlcloud: AWS APIs library for Erlang



[![Build Status](https://github.com/erlcloud/erlcloud/workflows/build/badge.svg)](https://github.com/erlcloud/erlcloud/actions/workflows/ci.yml)

[![Hex.pm](https://img.shields.io/hexpm/v/erlcloud)](https://hex.pm/packages/erlcloud)

[![Hex.pm](https://img.shields.io/hexpm/l/erlcloud)](COPYRIGHT)



This library is not developed or maintained by AWS thus lots of functionality

is still missing comparing to [aws-cli](https://aws.amazon.com/cli/) or

[boto](https://github.com/boto/boto).  Required functionality is being added

upon request.



Service APIs implemented:



- Amazon Elastic Compute Cloud (EC2)

- Amazon EC2 Container Service (ECS)

- Amazon Simple Storage Service (S3)

- Amazon Simple Queue Service (SQS)

- Amazon SimpleDB

- Amazon Mechanical Turk

- Amazon CloudWatch (MON)

- Amazon CloudSearch

- Amazon Inspector

- Amazon Key Management Service (KMS)

- Amazon DirectConnect

- Amazon DynamoDB & DDB streams (ddb2)

- Amazon Autoscaling (AS)

- Amazon CloudTrail (CT)

- Cloud Formation (CFN)

- Config

- ElasticLoadBalancing (ELB)

- Identity and Access Management (IAM)

- Kinesis

- Glue (Catalog table, Crawlers and Job APIs support)

- Athena

- Step Functions (SF)

- CloudWatch

- MechanicalTurk

- Simple DB (SDB)

- Relational Data Service (RDS)

- Simple Email Service (SES)

- Short Token Service (STS)

- Simple Notification Service (SNS)

- Web Application Firewall (WAF)

- AWS Cost and Usage Report API

- AWS Secrets Manager

- AWS Systems Manager (SSM)

- and more to come



The majority of API functions have been implemented.  Not all functions have

been thoroughly tested, so exercise care when integrating this library into

production code. Please send issues and patches.



The libraries can be used two ways.  You can:



- specify configuration parameters in the process dictionary. Useful for simple

  tasks, or

- create a configuration object and pass that to each request as the final

  parameter. Useful for Cross AWS Account access



## Roadmap



Below is the library roadmap update along with regular features and fixes.



- 3.0.X

  - ~~Remove R16 support~~ __done__

  - Support maps



- 3.X.X

  - Fix dialyzer findings and make it mandatory for the library

  - Only SigV4 signing and generalised in one module. Keep SigV2 in SBD section only

  - No more `erlang:error()` use and use of regular tuples as error API.

    Breaking change.



### Major API compatibility changes between 0.13.X and 2.0.x



- ELB APIs

- ... list to be filled shortly



### Supported Erlang versions



At the moment we support the following OTP releases:



- 19.3

- 20.3

- 21.3

- 22.3

- 23.3

- 24.3

- 25.3

- 26.2

- 27.1



This list is determined by ensuring eunit tests and dialyzer checks succeed for these versions, but not all of these

versions are in active use by library authors. Please report any issues discovered in actual use.



The Github Actions test runners only support OTP 24+ due to runtime issues, but OTP 19-23 were tested locally with unmodified,

official [Erlang docker images](https://hub.docker.com/_/erlang). Dialyzer checks run against the latest hex-published hackney

for OTP 24+, but a previous versions of hackney (1.15.0) and its dependency parse_trans (3.2.0) were used to do dialyzer checks

for OTP 19-23 due to newer versions of parse_trans requiring OTP 21+.



## Getting started



You need to clone the repository and download rebar/rebar3 (if it's not already

available in your path).



```sh

git clone https://github.com/erlcloud/erlcloud.git

cd erlcloud

wget https://s3.amazonaws.com/rebar3/rebar3

chmod a+x rebar3

```



To compile and run erlcloud:



```sh

make

make run

```



To use erlcloud in your application, add it as a dependency in your

application's configuration file.  erlcloud is also available as a [Hex](https://hex.pm) package,  refer to the Hex [`mix` usage docs](https://hex.pm/docs/usage) or [`rebar3` usage docs](https://hex.pm/docs/rebar3-usage) for more help including dependencies using Hex syntax.



To use erlcloud in the shell, you can start

it by calling:



```erlang

application:ensure_all_started(erlcloud).

```



### Using Temporary Security Credentials



When access to AWS resources is managed through [third-party identity

providers](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-idp.html)

it is performed using [temporary security

credentials](http://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp_use-resources.html).



You can provide your AWS credentials in OS environment variables



```sh

export AWS_ACCESS_KEY_ID=

export AWS_SECRET_ACCESS_KEY=

export AWS_SESSION_TOKEN=

export AWS_DEFAULT_REGION=

```



If you did not provide your AWS credentials in the OS environment variables,

then you need to provide configuration read from your profile:



```erlang

{ok, Conf} = erlcloud_aws:profile().

erlcloud_s3:list_buckets(Conf).

```



Or you can provide them via `erlcloud` application environment variables.



```erlang

application:set_env(erlcloud, aws_access_key_id, "your key"),

application:set_env(erlcloud, aws_secret_access_key, "your secret key"),

application:set_env(erlcloud, aws_security_token, "your token"),

application:set_env(erlcloud, aws_region, "your region"),

```



### Using Access Key



You can provide your AWS credentials in environmental variables.



```sh

export AWS_ACCESS_KEY_ID=

export AWS_SECRET_ACCESS_KEY=

```



If you did not provide your AWS credentials in the environment variables, then

you need to provide the per-process configuration:



```erlang

erlcloud_ec2:configure(AccessKeyId, SecretAccessKey [, Hostname]).

```



Hostname defaults to non-existing `"ec2.amazonaws.com"` intentionally to avoid

mix with US-East-1 Refer to

[aws_config](https://github.com/erlcloud/erlcloud/blob/master/include/erlcloud_aws.hrl)

for full description of all services configuration.



Configuration object usage:



```erlang

EC2 = erlcloud_ec2:new(AccessKeyId, SecretAccessKey [, Hostname])

erlcloud_ec2:describe_images(EC2).

```



### aws_config



The [aws_config](https://github.com/erlcloud/erlcloud/blob/master/include/erlcloud_aws.hrl)

record contains many valuable defaults, such as protocols and ports for AWS

services. You can always redefine them by making new `#aws_config{}` record and

changing particular fields, then passing the result to any `erlcloud` function.



But if you want to change something in runtime this might be tedious and/or not

flexible enough.



An alternative approach is to set default fields within the `app.config ->

erlcloud -> aws_config` section and rely on the config, used by all functions

by default.



Example of such `app.config`:



```erlang

[

  {erlcloud, [

      {aws_config, [

          {s3_scheme, "http://"},

          {s3_host, "s3.example.com"}

      ]}

  ]}

].

```



### VPC endpoints



If you want to utilise AZ affinity for VPC endpoints you can configure those in

application config via:



```erlang

{erlcloud, [

    {services_vpc_endpoints, [

        {<<"sqs">>, [<<"myAZ1.sqs-dns.amazonaws.com">>, <<"myAZ2.sqs-dns.amazonaws.com">>]},

        {<<"kinesis">>, {env, "KINESIS_VPC_ENDPOINTS"}}

    ]}

]}

```



Two options are supported:



- explicit list of Route53 AZ endpoints

- OS environment variable (handy for ECS deployments). The value of the

  variable should be of comma-separated string like

  `"myAZ1.sqs-dns.amazonaws.com,myAZ2.sqs-dns.amazonaws.com"`



Upon config generation, `erlcloud` will check the AZ of the deployment and

match it to one of the pre-configured DNS records. First match is used and if

not match found default is used.



## Basic use



Then you can start making API calls, like:



```erlang

erlcloud_ec2:describe_images().

% list buckets of Account stored in config in process dict

% of of the account you are running in.

erlcloud_s3:list_buckets().

erlcloud_s3:list_buckets(erlcloud_aws:default_cfg()).

% List buckets on 3d Account from Conf

erlcloud_s3:list_buckets(Conf).

```



Creating an EC2 instance may look like this:



```erlang

start_instance(Ami, KeyPair, UserData, Type, Zone) ->

    Config = #aws_config{

            access_key_id = application:get_env(aws_key),

            secret_access_key = application:get_env(aws_secret)

           },

    InstanceSpec = #ec2_instance_spec{image_id = Ami,

                                      key_name = KeyPair,

                                      instance_type = Type,

                                      availability_zone = Zone,

                                      user_data = UserData},

    erlcloud_ec2:run_instances(InstanceSpec, Config).

```



For usage information, consult the source code and

[GitHub repo](https://hexdocs.pm/erlcloud). For detailed API description refer

to the AWS references at:



- [AmazonEC2](http://docs.aws.amazon.com/AWSEC2/latest/APIReference/Welcome.html)

- [Amazon S3](http://docs.aws.amazon.com/AmazonS3/latest/API/Welcome.html)

- and [other services](https://aws.amazon.com/documentation/)



## Notes



Indentation in contributions should follow indentation style of surrounding

text.  In general it follows default indentation rules of official erlang-mode

as provided by OTP team.



## Best Practices



- All interfaces should provide a method for working with non-default config.

- Public interfaces with paging logic should prefer `{ok, Results, Marker}`

  style to the `{{paged, Marker}, Results}` found in some modules.

  In case of records output, tokens should be part of the record.

- Passing next page `NextToken`, `NextMarker` is preferred with `Opts` rather

  than a fun parameter like found in many modules.

- Public interfaces should normally expose proplists over records. All new

  modules are preferred to have both.

- Exposed records are to be used only for complex outputs. Examples to follow:

  ddb2, ecs.

- Library should not expose any long running or stateful processes - no

  gen_servers, no caches and etc.



## Publishing to hex.pm



erlcloud is available as a [Hex](https://hex.pm) package. A new version of the package can be published by maintainers using mix or rebar3. A `hex-publish` make target that uses rebar3 is provided for maintainers to use or reference when publishing a new version of the package.



Github Actions will eventually be used to automatically publish new versions.