Environment Properties Plugin

This plugin intends to make the management of environment specific properties easier, often it is a pain if you have and environment specific properties that is the same in a number of environments but needs to vary in one or a couple of environments. This can lead to duplication for those environments where the value remains the same, which is the main problem this plugin attempts to address.

How does it work

It does this by using a single yaml file for all your environment properties definitions, but the structure of this file means that it is possible to specify default values for any property you like, but also provide environment specific values where they are required. A very basic example is shown below:

properties:
  default: &config-default
    app.name: test-service
    abc.url: http://localhost:8080

environments:

  local:
    <<: *config-default

  aat: &config-aat
    <<: *config-default

    app.name: aat-service

  aat1:
    <<: *config-aat

    abc.url: http://aat1:8081

  aat2:
    <<: *config-aat

    abc.url: http://aat2:8082

  sit:
    <<: *config-default

    app.name: test-service-sit
    abc.url: http://sit:8080

In the above example, the properties files produced for each environment would be as follows.

For the local environment, there are no environment specific values, so all default values are used

# generated from properties.yml for local environment
app.name=test-service
abc.url=http://localhost:8080

For the aat environment, abc.url is not specified so the default value is used and there is an environment specific value for app.name so that is used instead

# generated from properties.yml for aat environment
app.name=aat-service
abc.url=http://localhost:8080

For the sit environment, environment specific values are provided for both app.name and abc.url so both of those values are used and no default values are picked up

# generated from properties.yml for local environment
app.name=test-service-sit
abc.url=http://sit:8080

Cascading

You don't just have to extend from the default properties, it is also possible for one environment to use another as its default values, in the above examples, the aat, aat1 and aat2 configurations demonstrate this. The snippet below gives the aat config the name config-aat (this is done by adding the &config-aat after the initial definition) this is done so that it can be referenced as a default for the aat1 and aat2 configs. The next line (<<: *config-default) states that the default config should be inherited for the aat config:

  aat: &config-aat
    <<: *config-default

The aat1 and aa2 configs use the same config to inherit from the aat config, this is shown again in the snippets below:

  aat1:
    <<: *config-aat

  aat2:
    <<: *config-aat

As mentioned above, for the aat environment, abc.url is not specified so the default value is used and there is an environment specific value for app.name so that is used instead

# generated from properties.yml for aat environment
app.name=aat-service
abc.url=http://localhost:8080

For the aat1 environment, app.name is not specified so the aat value is used and there is an environment specific value for abc.url so that is used instead

# generated from properties.yml for aat1 environment
app.name=aat-service
abc.url=http://aat1:8081

For the aat2 environment, again app.name is not specified so the aat value is used and there is an environment specific value for abc.url so that is used instead

# generated from properties.yml for aat2 environment
app.name=aat-service
abc.url=http://aat2:8082

Usage

If you are using gradle version < 2.1 (you should upgrade!)

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.github.michaelruocco:environment-properties-plugin:0.1.0'
    }
}

apply plugin: 'com.github.michaelruocco.environment-properties'

or alternatively:

plugins {
    id 'com.github.michaelruocco.environment-properties-plugin' version '0.1.0'
}

The plugin will add two new tasks to your gradle build:

• generateEnvironmentProperties
• generateMultipleEnvironmentProperties

As you would expect, the first task can be used to create a single environment properties file, the second can generate one or more environment properties files. Which you choose to use will depend on how your project and CI process is set up.

Generating a single environment properties file

If you want to create a single environment properties file then you can set up the task by telling it the path to the yaml file to use as input and the path to where you would like your properties file to be generated, finally you need to provide an argument which specifies which environment you want to build the properties for.

generateEnvironmentProperties {
    yamlPath = 'properties.yml'
    environment = 'aat'
    propertiesPath = 'config/environment.properties'
}

When this task is run it will generate the properties file at config/environment.properties which will contain the values for the aat environment. Note - you will most likely want to specific the environment value from some kind of dynamic value, e.g. passed by a gradle property or maybe read from an environment variable rather than hardcoding, the hardcoded example above is just for simplicity and to demonstrate the way the plugin works.

Generating multiple environment properties file

It is also possible to generate multiple environment properties files if required, the task configuration is similar to the above example with a few tweaks:

generateMultipleEnvironmentProperties {
    yamlPath = 'properties.yml'
    environments = [ 'aat1', 'sit' ]
    propertiesPath = 'config/{{env}}/environment.properties'
}

The yaml path is obviously the same as it was for the previous task, it specifies the location of the yaml file to read the property values above. For this task it is possible to specify multiple environments, to do this it is also wise to add an environment placeholder in the properties path, otherwise the plugin will simply overwrite each property file, meaning that only one would be produced! In the example above, the task would generate two properties files at the following locations:

• config/aat1/environment.properties
• config/sit/environment.properties

Default config

By default if you specify an environment that is not present in the yaml file that is specified the plugin will return an error stating that the environment cannot be found in the yaml file. There may be cases where you have lots of environments that all use a basic or default configuration, if so, it can be a pain to have to specify lots of blank environment property blocks that just inherit from a default config, e.g:

properties:
  default: &config-default
    app.name: test-service
    abc.url: http://localhost:8080

environments:

  dev:
    <<: *config-default

  aat:
    <<: *config-default

  sit:
    <<: *config-default

As a solution to this empty duplication it is possible to provide a default environment that will be used in the event and environment is not found, in this scenario the default environment properties will be used to generate the file instead of the plugin throwing an error. To configure a default environment you simply add another line of configuration to the task in your gradle file:

generateMultipleEnvironmentProperties {
    yamlPath = 'properties.yml'
    environments = [ 'dev', 'aat', 'sit' ]
    propertiesPath = 'config/{{env}}/environment.properties'
    defaultEnvironment = 'default'
}

This configuration would mean you would no longer need the empty definitions for dev, aat and sit shown in the yaml example above and your dev, aat and sit properties would still be generated using the default config values, instead of just seeing an error returned because those environments don't exist in the yaml.

Running the Tests

You can run the unit and tests for this project by running the following command:

./gradlew clean build

Checking dependencies

You can check the current dependencies used by the project to see whether or not they are currently up to date by running the following command:

./gradlew dependencyUpdates