# Blinkist::Config

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This GEM allows you to access configuration stores with different adapters. Here're some examples of usage:

### Using the ENV

```ruby
# First setup the Config to use the ENV as config store

Diplomat.configure do |config|
  config.url = "http://172.17.0.1:8500"
end

Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = :env
Blinkist::Config.error_handler = :strict

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is being translated to ENV["SOME_FOLDER_CONFIG"]
```

### Error handling

When configured with `Blinkist::Config.error_handler = :strict` (as recommended)
reading a configuration entry for which the value is missing 
(for example missing enviroment variables) will cause
`Blinkist::Config::ValueMissingError` to be raised.

There is also an alternative mode `Blinkist::Config.error_handler = :heuristic` which
will raise exceptions only when `Blinkist::Config.env == "production"`.

This alternative mode is also the default for compatibility.

### Having a default value

If you don't want `Blinkist::Config.get!` to scream at you for missing
configuration entries then you canprovide a default value as a second
paramter to `get!`:

```ruby
my_config_value = Blinkist::Config.get! "some/folder/config", "default value"

# If ENV["SOME_FOLDER_CONFIG"] is nil, "default value" will be returned
```

### Using Diplomat & Consul

If you want to use Consul's key value store, simply use our diplomat adapter.

* [https://www.consul.io/](https://www.consul.io/)
* [https://github.com/WeAreFarmGeek/diplomat](https://github.com/WeAreFarmGeek/diplomat)

The GEM expects consul to listen to `http://172.17.0.1:8500`

```ruby
# First setup the Config to use the ENV as config store
Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = ENV["CONSUL_AVAILABLE"] == "true" ? :diplomat : :env

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is will try to get a value from Consul's KV store at "my_nice_app/some/folder/config"
```

### Using Diplomat with a folder scope
```ruby
# Here we setting a scope outside of the app

my_config_value = Blinkist::Config.get! "another/config", scope: "global"

# This will replace `my_nice_app` with `global` and try to resolve "global/another/config"
# With :env the scope will simply be ignored
```

### Using AWS SSM

If you want to use EC2's key value store SSM, simply use our aws_ssm adapter. It'll automatically try to decrypt all keys.

The GEM expects the code to run in an AWS environment with properly set up IAM.

```ruby
Blinkist::Config.env = ENV["RAILS_ENV"]
Blinkist::Config.app_name = "my_nice_app"
Blinkist::Config.adapter_type = ENV["SSM_AVAILABLE"] == "true" ? :aws_ssm : :env

my_config_value = Blinkist::Config.get! "some/folder/config"

# This is will try to get a parameter from SSM at "/application/my_nice_app/some/folder/config"

# You can also preload all parameters to avoid later calls to SSM
Blinkist::Config.preload
Blinkist::Config.preload scope: "global" # in case you need also another scope being preloaded
```

### Using SSM with a folder scope
```ruby
# Here we setting a scope outside of the app

my_config_value = Blinkist::Config.get! "another/config", scope: "global"

# This will replace `my_nice_app` with `global` and try to resolve "/application/global/another/config"
```


## Installation

Add this line to your application's Gemfile:

```ruby
gem "blinkist-config"
```

## Usage

You have to set up the GEM before you can use it. The basic setup requires this

```ruby
Blinkist::Config.env = "production" || "test" || "development"
Blinkist::Config.app_name = "your_app_name" # Used only with diplomat adapter
Blinkist::Config.adapter_type = :diplomat || :env
```

It's best to drop a `config.rb` into your app and load this file before every other file. In Rails you can link it into your `application.rb`

```ruby
require_relative "boot"
require_relative "config"

require "rails"
# ...
```

## Development

You can build this project easily with [docker compose](https://docs.docker.com/compose/).

```
docker-compose run rake
```

This will execute rake and run all specs by auto correcting the code with rubocop.

If you're ready to tag a new version, do this

```
docker-compose run gem bump -t -v major|minor|patch
```

To deploy to rubygems.org do this then

```
docker-compose run gem release
```

You'll have to have proper rights to access rubygems.org

## Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/blinkist/blinkist-config.


## License

The gem is available as open source under the terms of the [MIT License](http://opensource.org/licenses/MIT).