Environment Config Generator

pub package

Environment specific config generator.

Allows to specify env configuration during CI/CD build.

Primarily created to simplify Flutter build configuration.

Features

  • flexible configuration for Config class generation
  • allows to specify pattern for field values
  • allows to define required and optional keys for generation
  • allows to export variables to .env file

Note for Flutter developers

This package still will be maintained, but if you are using Flutter version 1.17 and higher, consider using compile-time variables to configure your environments instead of this package. More about compile-time variables you can read here

Migration from 1.x.x to 2.x.x

In 1.x.x path for .env was generated against lib/ folder. Starting from 2.x.x path for .env file is generated against your root app folder.

So by default .env file will be generated alongside with pubspec.yaml and other root files.

Table of contents

Getting Started

Install package as dependency. Or use global active

dart pub global activate environment_config

Create environment_config.yaml or update package.yaml file with following code

Note This is an example with ALL possible params

environment_config:
  path: environment_config.dart # optional, result file path against `lib/` folder
  dotenv_path: .env # optional, result file path for .env file against project root folder
  class: EnvironmentConfig # optional, class name
  dev_extension: # optional, by default undefined, allows to specify command option to use extension
  
  fields: # set of fields for command
    some_key: # key name
      type: # optional, default to 'String'
      short_name: # optional, short name for key during command run
      const: # optional, default to TRUE
      pattern: # optional, specified pattern for key value, use __VALUE__ to insert entered value anywhere in the pattern
      default: # optional, default value for key, if not provided key will be required during command run
      dotenv: # optional, default to FALSE, if this field should be added to .env file
      config_field: # optional, default to TRUE, if this field should be added to Dart file
      env_var: # optional, global environment variable name
      static: # options, default to TRUE, if this field should be static, if FALSE, `const` will be be ignored
      
  imports: # optional, array of imports, to include in config file
    - package:some_package
      
  extensions: # set of extensions for default field list
    some_extension: # extension name
      some_key:
        const: # optional, overrides `const` value for the field
        pattern: # optional, overrides `pattern` value for the field
        default: # optional, overrides `default` value for the field
        env_var: # optional, overrides `env_var` value for the field
        
    imports: # optional, adds set of imports to main configulration
      - package:some_other_package

Run pub get to install dependencies. (if you installed it as deps in you project)

After config is specified in YAML file run following command

pub run environment_config:generate --some_key=some_value

Or for flutter project

flutter pub run environment_config:generate --some_key=some_value

Or just next command if you installed package globally

environment-config-generate --some_key=some_value

This command with generate file, that was specified in path key with class, fields and name specified in yaml config.

Import this file into your application and use it.

Note: It's recommended to add generated config files to .gitignore

Why this package is needed?

This package allows to integrate config generation based on environment in an easy way.

Unlike most env specific configurations this package can be added to CI/CD build process to generate config file with values, that specific to particular env, without need to specify your Prod credentials anywhere except your build process.

Also reading this values doesn't require async process, that will decrease you app start time

Obviously this package doesn't obfuscate or encrypt config values, but generated Dart file will be build and obfuscated with rest of your mobile application code. If you want to secure your sensitive information you can use encrypted values and pattern key to wrap it with your decrypt library. But overall keep in mind that there is no way to fully secure your app from reverse engineering

Also this package allows to generate .env file with same key value pairs

Config

Command options

During command run YAML file will be parsed to define keys for command.

  • config - path to custom yaml file with package configuration
  • config_extension - name of the extension, that should be used for config generation
  • any key name, that specified in yaml file under fields key
  • dev_extension key name, allows to use this key as bool flag

For example. If you have next yaml config

environment_config:
  fields:
    key_one:
      short_name: o #optional
    key_two:
      short_name: t #optional

You will be able tou run command with following options

flutter pub run environment_config:generate --key_one=something --key_two=other

Or (if short_name is specified)

flutter pub run environment_config:generate -o something -t other

Both commands will generate same dart class

class EnvironmentConfig {
  static const String key_one = 'something';

  static const String key_two = 'other';
}

Multiple config files

If you want to use different config YAML files for different environment or you need to generate multiple configurations, use config key during command run

flutter pub run environment_config:generate --config=path/to/file.yaml

Class configuration

Class and file can be configured with next options

  • path - path to file against lib folder, by default it's environment_config.dart
  • dotenv_path - path to file against root app folder, by default it's .env
  • class - class name, by default will be generated based on file name
  • const - optional, defines if class constructor should be defined as const.
  • imports - array of imports to add to generated config file
  • fields- set of fields, that should be defined in configuration files
  • dev_extension - defines which extension should be treated as dev extension, if specified - it's value can be used during command run as bool flag
  • extensions - set of configurations, that can extend default config

If class is not specified value for class name will be generate based on file name in path field. It will convert snake_case into CamelCase.

Field dotenv_path will be used only if at least one field contains dotenv: true

Config Examples

Custom path example

environment_config:
  path: config/some_config.dart
  
  ...

Will create file with name some_config.dart in lib/config folder with following class

class SomeConfig {
  ///
}

Custom class name example

environment_config:
  path: config/some_other_config_file.dart
  class: OtherClass
  
  ...

will create file with name some_other_config_file.dart in lib/config folder with following class

class OtherClass {
  ///
}

Class with const constructor

environment_config:
  class: OtherClass
  const: true
  
  ...

will create config with following class

class OtherClass {
  const OtherClass();
  ///
}

If const is used it will force class to have const constructor or without it.

Field configuration

To define fields for config definition, provide key set under fields key.

Configuration accepts any amount of field keys. At least one field should be specified

Note: config key can't be used for field definition. It's reserved by command itself to define path to custom config yaml file

Note If dev_extension is defined, its value can't be used as field name

Each field accepts next params, each param is optional

  • type - field type, default to String
  • const - if field should be const, default to TRUE. If FALSE, final modifier will be used instead
  • static - if field should be static, default to TRUE. If FALSE, const option will be ignored
  • pattern - pattern for field value. Inside value for this field __VALUE__ can be used. It will be replaced with actual entered value or with default value
  • default - default value for the field. If not specified, field will be treated as required
  • short_name - short key name, that can be used during command run instead of full field name. Accepts 1 symbol values only
  • dotenv - bool flag, if TRUE this field will be added to .env file.
  • env_var - environment global variable name
  • config_field - default to TRUE, indicates if this field should be defined in Dart class config

If you want to generate .env file in addition to class config, at least ONE key should have dotenv to be TRUE. Otherwise .env file won't be generated

If field contains dotenv: false (which is default state) and config_field: false field will be ignored

Note If field config doesn't have default key specified it will be treated as required. Which means that you need provide value for your field in one of the following way:

  • argument during command run
  • global env variable, if env_var is specified

Note: If pattern key is specified and const is TRUE ensure your pattern also contains const modifier like this

environment_config:
  fields:
    some_key:
      pattern: const CustomClass('__VALUE__')

Fields config examples

Pattern example

environment_config:
  fields:
    numberValue:
      type: num
      const: false
      short_name: o #optional
    customClassValue:
      type: CustomClass
      pattern: const CustomClass('__VALUE__')

This config allows to run next command

flutter pub run environment_config:generate -o 345 --customClassValue=something

It will generate following class

class EnvironmentConfig {
  static final num numberValue = 345;

  static const CustomClass customClassValue = const CustomClass('something');
}

DotEnv example

To create .env at least one key should have dotenv: true attribute

environment_config:
  fields:
    first_key: # define field only in Dart class
      type: num
    second_key:
      dotenv: true # will define field in Dart and in `.env`
    third_key:
      dotenv: true # will define field in `.env`
      config_field: false # will exclude field from Dart config file

Note If dotenv: false and config_field: false this field won't be added to .env and Dart config class

This command

flutter pub run environment_config:generate --first_key=123 --second_key=456 --third_key=789

will generate Dart class config in lib/ folder

class EnvironmentConfig {
  const EnvironmentConfig();

  static const num first_key = 123;

  static const String second_key = '456';
}

and following .env in your root app folder

second_key=456
third_key=789

Global environment variable example

If you want to use value from environment variable, just define key env_var.

environment_config:
  fields:
    first_key:
      env_var: PATH

In that way generator will try to get value from PATH global variable for your key.

Generator will use next priority:

  • value from command arguments
  • value from environment variable PATH
  • value from Extensions default key (if extension was used that has default key)
  • value from default key (if it was specified)

Extensions

Extensions allows you to define set of override rules for fields and imports.

Primarily extensions are needed to override main configuration and provide some specific settings for environment like dev. That is why it allows to override just specific set of configuration keys for specific field:

  • const
  • pattern
  • default
  • env_var

Extension won't override other field keys to keep config class signature consistent (if you need to add other keys in this list, feel free to open an issue for that).

Also extension allows you to define import list in addition to default config. If extension is used - import list will be merged from default config and extension config

Basic Extension config usage

To use extension define it in config:

environment_config:
  fields:
    first_key:
    
  imports:
    - some:package
      
  extensions:
    dev: # your extension name
      fields:
        first_key:
          default: some value
      
      imports:
        - other:package

Then if you run command like this

flutter pub run environment_config:generate

It will throw an error that first_key is required. But you use extension

flutter pub run environment_config:generate --config-extension=dev

It will generate following config class

import 'some:package';
import 'other:package';

class EnvironmentConfig {
  static const String first_key = 'some value';
}

Development Extension example

Note Don't use development extension in your automated build tools. There is a plan add verbose command run support eventually.

Most common case when extension can be used is for your Dev environment. In that way your default config will ensure that all fields are provided by build tool, and in same time - to generate config for dev environment, you won't need to define values for your fields.

To enable dev extension just add dev_extension

environment_config:
  dev_extension: dev # `dev` here is the name of you extension
  fields:
    first_key:
    
  imports:
    - some:package
      
  extensions:
    dev:
      fields:
        first_key:
          default: some value
      
      imports:
        - other:package

Then you can run command like this, where dev is key name from dev_extension

flutter pub run environment_config:generate --dev

Integration with CI/CD

To add config generation into any CI/CD, add command execution after deps are installed and before build run.

flutter pub run environment_config:generate --<key_name>=<key_value>

If your build tool allows to specify environment variables (for example like Code Magic does), you can specify all needed key/values there. And in YAML config just define env_var in keys, where you want to use them with same variable name like in your build tool. If all keys has env_var specified and your build tool also provides all needed values, you can run generator just like this.

flutter pub run environment_config:generate

Integration with other packages

Note Next package was selected just for an example. You can choose any other package that works with .env file

Support of .env generation was primarily added to generate config for packages that relies on it.

For example .env generation feature can be used with flutter_config package. This particular package allows you to pass environment variables from .env into your native layer like your plugins or Android/iOS app configuration.

For more info see this docs for Android or iOS

Changelog

Please see the Changelog page to know what's recently changed.

Bugs/Requests

If you encounter any problems feel free to open an issue. If you feel the library is missing a feature, please raise a ticket on Github and I'll look into it. Pull request are also welcome.

Libraries

argument_parser
config
config_field_type
config_generator
config_loader
errors/config_error
errors/extension_not_found_error
errors/file_not_found_error
errors/malformed_config_error
errors/validation_error
field_config
generator
platform_value_provider