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https://github.com/googleapis/elixir-google-api

Elixir client libraries for accessing Google APIs.
https://github.com/googleapis/elixir-google-api

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Elixir client libraries for accessing Google APIs.

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# GoogleApis



This repository contains all the client libraries to interact with Google APIs.

These client libraries are created under `clients/` and each should contain its

own README.



The main folder contains the code necessary to generate these client libraries.



**NOTE: These generated clients are under development and should be considered

experimental!**



## Usage



### Installation



All available Google API clients can be found [on hex.pm][hex_pm]. Add a client

to your project's `mix.exs` under `deps`:



```ex

defmodule YourApplication.Mixfile do

  use Mix.Project

  #...



  # Run "mix help deps" to learn about dependencies.

  defp deps do

    [

      {:google_api_storage, "~> 0.19.0"},

      {:goth, "~> 1.2.0"}

    ]

  end

end

```



> Note the [goth][goth] package, which handles Google Authentication, is also

> required.



Next, run `mix deps.get` to pull down the dependencies:



```sh

$ mix deps.get

```



Now you can make an API call by obtaining an access token and using the

generated modules.



### Obtaining an Access Token



#### Service Accounts



Authentication is typically done through [Application Default Credentials][adc]

which means you do not have to change the code to authenticate as long as

your environment has credentials. Start by creating a

[Service Account key file][service_account_key_file]. This file can be used to

authenticate to Google Cloud Platform services from any environment. To use

the file, set the `GOOGLE_APPLICATION_CREDENTIALS` environment variable to

the path to the key file, for example:



    export GOOGLE_APPLICATION_CREDENTIALS=/path/to/service_account.json



If you are deploying to App Engine, Compute Engine, or Container Engine, your

credentials will be available by default.



#### OAuth 2.0



Many APIs (like Drive, Gmail, and YouTube) require you to use OAuth 2.0 to

authorize requests on behalf of an authenticated user. For an example using

the [oauth2-library][oauth2-library], see the [auth sample][auth-sample].



We've also provided a mix task to fetch a token for testing. The following

command requests a token for the Drive full access scope:



```bash

$ export GOOGLE_CLIENT_ID=[YOUR-OAUTH-CLIENT-ID]

$ export GOOGLE_CLIENT_SECRET=[YOUR-OAUTH-CLIENT-SECRET]

$ mix google_apis.auth https://www.googleapis.com/auth/drive

Open the following link in your brower:

https://accounts.google.com/o/oauth2/auth?[some-long-url]

Enter verification code:

```



Once you've logged in and authorized the application, copy the code param from

the web browser's url and paste into the console. The script will then fetch

your OAuth access token.



```bash

Token: [your-oauth-token]

```



You can then use this token for your testing:



```elixir

connection = GoogleApi.Drive.V3.Connection.new("your-oauth-token")

{:ok, file_list} = GoogleApi.Drive.V3.Api.Files.drive_files_list(conn)

```



### Making a Request



```ex

# Obtain an access token using goth

{:ok, token} = Goth.Token.for_scope("https://www.googleapis.com/auth/cloud-platform")

conn = GoogleApi.Storage.V1.Connection.new(token.token)



# Call the Storage V1 API (for example) to list buckets

{:ok, response} = GoogleApi.Storage.V1.Api.Buckets.storage_buckets_list(conn, project_id)



# Print the response

Enum.each(response.items, &IO.puts(&1.id))

```



### What's Next?



Take a look at our [elixir-samples repository][elixir-samples] repository for

examples of calling individual APIs and a getting started tutorial app.



## Generating Clients



### Setup



1. Install nodejs if not already installed.

1. Install nodejs dependencies:



```bash

$> npm install

```



1. Install elixir dependencies:



```bash

$> mix deps.get

```



This project provides 4 mix tasks to componentize the build process:



1. `mix google_apis.discover` - Select which APIs to build

1. `mix google_apis.fetch` - Download the selected API specifications in Google

   discovery format

1. `mix google_apis.convert` - Convert the selected API specifications from

   Google discovery format to OpenApi v2 (formerly known as Swagger)

1. `mix google_apis.build` - Generate API clients



### Selecting APIs



The `mix google_apis.discover` task queries Google's API [discovery

directory][discovery-directory]. The contents of this file are downloaded to a

staging file (`api-candidate.json`) under the config directory.



You can change the name of the file by providing a filename argument to the mix

task:



```bash

$> mix google_apis.discover foo.json

```



Note that this task is not one that should be run often, as the

`config/api.json` is considered configuration regarding which APIs to generate.



### Fetching API Specifications



The `mix google_apis.fetch` task iterates through the list of API

specifications in the `config/api.json` file and downloads the specification to

the `specifications/gdd` folder with the format of `-.json`.



You can limit which APIs to fetch by providing an API name argument to the mix

task:



```bash

$> mix google_apis.fetch CloudTrace

```



### Converting API Specifications



The next step is to convert the API specifications from Google's discovery

format to OpenApi format.  The `mix google_apis.convert` task iterates through

the list of API specifications in the `config/api.json` file and converts each

found Google discovery specification to an equivalent* OpenApi version.



You can configure the converter by modifying the `config/config.exs` setting:



```elixir

config :google_apis, spec_converter: 

```



The default converter uses the node package

[api-spec-converter][api-spec-converter].  You can also limit which APIs to

convert by providing an API name argument to the mix task:



```bash

$> mix google_apis.convert CloudTrace

```



### Building API Clients



The `mix google_apis.build` task iterates through the list of API

specifications in the `config/api.json` file and generates an Elixir client

library in the `clients` folder.



You can configure the converter by modifying the `config/config.exs` setting:



```elixir

config :google_apis, client_generator: GoogleApis.Generator.SwaggerCli

```



The default generator uses Docker and an image based off the [swagger-codegen

project][swagger-codegen]. You can further configure this converter by

modifying the `config/config.exs` setting:



```elixir

config :google_apis, swagger_cli_image: "swagger-cli"

```



You can also limit which APIs to generate by providing an API name argument to

the mix task:



```bash

$> mix google_apis.generate CloudTrace

```



## Contributing



Contributions to this library are always welcome and highly encouraged.



See [CONTRIBUTING](CONTRIBUTING.md) for more information on how to get started.



## License



Apache 2.0 - See [LICENSE](LICENSE) for more information.



## Disclaimer



This is not an officially supported Google product.



[adc]: https://cloud.google.com/docs/authentication#getting_credentials_for_server-centric_flow

[service_account_key_file]: https://developers.google.com/identity/protocols/OAuth2ServiceAccount#creatinganaccount

[discovery-directory]: https://www.googleapis.com/discovery/v1/apis

[api-spec-converter]: https://github.com/LucyBot-Inc/api-spec-converter

[swagger-codegen]: https://github.com/swagger-api/swagger-codegen

[hex_pm]: https://hex.pm/users/google-cloud

[goth]: https://hex.pm/packages/goth

[elixir-samples]: https://github.com/GoogleCloudPlatform/elixir-samples

[oauth2-library]: https://github.com/scrogson/oauth2

[auth-sample]: https://github.com/GoogleCloudPlatform/elixir-samples/tree/master/auth