CFEnv

A helper application for grabbing and parsing CloudFoundry Environment Variables.

A small application for parsing and retrieving VCAP_SERVICES, and VCAP_APPLICATION.

API Preview

> MyApp.Env.service_credentials("dynamo-db")
%{"database" => "dynamo", "accessKeyId" => "abcd", "secretAccessKey" => "defg",
  "tableName" => "test-table" }

Or grabbing the current application name.

iex(1)> MyApp.Env.app_name()
"test_app"

See the documentation for other api examples.

Migration to 1.0.0

CFEnv is no longer an application, but a process started within your application, with functions created as a macro. All functionality is present, but CFEnv.Services and CFEnv.Application have been combined. See usage instructions below, and the CFEnv module.

Usage

You’ll need to add cf_env as a dependancy to your mix.exs file, along with a module for parsing json. CFEnv supports Poison and Jason by default, though custom JSON adapters can be provided. See CFEnv.Adapters.JSON for details.

Dependancies

  def deps do
      [
        {:cf_env, "~> 1.0"},
        {:jason, "~> 1.1"},

        # or, if you prefer poison
        {:poison, "~> 3.0"}
      ]
  end

Then, fetch your dependencies:

  $ mix deps.get

You’ll need to create a module that represents your service bindings.

defmodule MyApp.Env do
  use CFEnv,
    otp_app: :my_app,
    json_engine: Jason
    ...

Finally, add the process to your supervision tree:

    # For Elixir v1.5 and later
    {MyApp.Env, [ default_bindings: %{} ]}

    # For Elixir v1.4 and earlier
    supervisor(MyApp.Env, [  default_bindings: %{}])

Configuration

You can provide options as application config, or with runtime config. Runtime config always overrides application config.

Application Config

config :my_app, MyApp.Env
  json_engine: Jason,
  default_services: %{
    "some_db" => %{
      "username" => System.get_env("TEST_USER"),
      "password" => System.get_env("TEST_PASSWORD")
    }
  }
  ...

Runtime Config

options = [
  json_engine: Jason,
  default_services: %{
    "some_db" => %{
      "username" => System.get_env("TEST_USER"),
      "password" => System.get_env("TEST_PASSWORD")
    }
  }]

# explicit start
MyApp.Env.start_link(])

# supervisor start
children = [
  {MyApp.Env, [options]}
]

Default Services

Working with VCAP_SERVICES can be a pain. Instead, default services bindings can be passed in as a map from configuration, where each key is a string. You can provide reasonable defaults for local development this way.

config :cf_env,
  default_services:
    %{ "service_name" => %{
        "username" => "u5er",
        "password" => "pa$$w0rd"
      }
    }

Data Conversion

On init, VCAP_SERVICES and VCAP_APPLICATION are parsed from JSON.

And each value is transformed into a map. If an alias key is present on the credentials, the service will be mapped to use that name instead. This is useful for updating the bindings for an application, without having to implement a code change, or affect other services using this binding.

Every map created this way is merged back into the provided default service map, with parsed CF services overwriting defaults, if any.

Currently only user-provided services are supported.

Conversion Example:

The following list of services:

{
  "user-provided": [
    {
      "name": "cf-env-test",
      "label": "user-provided",
      "tags": [],
      "credentials": {
          "database": "database",
          "password": "passw0rd",
          "url": "https://example.com/",
          "username": "userid"
      },
      "syslog_drain_url": "http://example.com/syslog"
    },
    {
      "name": "dynamo-db",
      "label": "user-provided",
      "tags": [],
      "credentials": {
        "alias": "alias-name",
        "database": "dynamo",
        "accessKeyId": "abcd",
        "secretAccessKey": "defg"
        "tableName": "test-table",
      },
      "syslog_drain_url": "http://example.com/syslog"
    }
  ]
}

is reduced to the following map:

%{
    # using the name
    "cf-env-test" => %{
        "name" => "cf-env-test",
        "label" => "user-provided",
        "tags" => [],
        "credentials" => %{
            "database" => "database",
            "password" => "passw0rd",
            "url" => "https://example.com/",
            "username" => "userid"
        },
        "syslog_drain_url" => "http://example.com/syslog"
    },
    # using the provided alias
    "another-cf-env-test" => %{
        "name" => "another-cf-env-test",
        "label" => "user-provided",
        "tags" => [],
        "credentials" => %{
            "alias" => "alias-name",
            "database" => "dynamo",
            "accessKeyId" => "abcd",
            "secretAccessKey" => "defg"
            "tableName" => "test-table",
        },
        "syslog_drain_url": "http://example.com/syslog"
    }
}

Local Development / Testing

Use the .env file to set up your local environment before testing.