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Vert.x Config

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Vert.x Config provides a way to configure your Vert.x application. It:

  • offers multiple configuration syntaxes (JSON, properties, Yaml (extension), Hocon (extension)…​

  • offers multiple configuration stores such as files, directories, HTTP, git (extension), Redis (extension), system properties and environment properties.

  • lets you define the processing order and overloading

  • supports runtime reconfiguration

Concepts

The library is structured around:

  • a*Config Retriever instantiated and used by the Vert.x application. It configures a set of configuration store Configuration store** defines a location from where the configuration data is read and also a format (JSON by default)

The configuration is retrieved as a JSON Object.

Using the Config Retriever

To use the Config Retriever, add the following dependency to the dependencies section of your build descriptor:

  • Maven (in your pom.xml):

<dependency>
 <groupId>io.vertx</groupId>
 <artifactId>vertx-config</artifactId>
 <version>3.6.2</version>
</dependency>

  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.6.2'
----

Once done, you first need to instantiate the ConfigRetriever:

require 'vertx-config/config_retriever'
retriever = VertxConfig::ConfigRetriever.create(vertx)

By default, the Config Retriever is configured with the following stores (in this order):

  • The Vert.x verticle config()

  • The system properties

  • The environment variables

  • A conf/config.json file. This path can be overridden using the vertx-config-path system property or VERTX_CONFIG_PATH environment variable.

You can configure your own stores:

require 'vertx-config/config_retriever'
httpStore = {
  'type' => "http",
  'config' => {
    'host' => "localhost",
    'port' => 8080,
    'path' => "/conf"
  }
}

fileStore = {
  'type' => "file",
  'config' => {
    'path' => "my-config.json"
  }
}

sysPropsStore = {
  'type' => "sys"
}


options = {
  'stores' => [
    httpStore,
    fileStore,
    sysPropsStore
  ]
}

retriever = VertxConfig::ConfigRetriever.create(vertx, options)

More details about the overloading rules and available stores are available below. Each store can be marked as optional. If a failure is caught while retrieving (or processing) the configuration from an optional store, the failure is logged, but the processing does not fail. Instead, an empty JSON object is returned ({}). To mark a store as optional, use the optional attribute:

require 'vertx-config/config_retriever'
fileStore = {
  'type' => "file",
  'optional' => true,
  'config' => {
    'path' => "my-config.json"
  }
}
sysPropsStore = {
  'type' => "sys"
}

options = {
  'stores' => [
    fileStore,
    sysPropsStore
  ]
}

retriever = VertxConfig::ConfigRetriever.create(vertx, options)

Once you have the instance of the Config Retriever, retrieve the configuration as follows:

retriever.get_config() { |ar_err,ar|
  if (ar_err != nil)
    # Failed to retrieve the configuration
  else
    config = ar
  end
}

Overloading rules

The declaration order of the configuration store is important as it defines the overloading. For conflicting key, configuration stores arriving last overloads the value provided by the previous configuration stores. Let’s take an example. We have 2 configuration stores:

  • A provides {a:value, b:1}

  • B provides {a:value2, c:2}

Declared in this order (A, B), the resulting configuration would be: {a:value2, b:1, c:2}.

If you declare them in the reverse order (B, A), you will get: {a:value, b:1, c:2}.

Using the retrieve configuration

The retrieve configuration allows:

  • configuring verticles,

  • configure ports, clients, locations and so on,

  • configuring Vert.x itself

This section gives a few examples of usage.

Configuring a single verticle

The following example can be placed in the start method of a verticle. It retrieves the configuration (using the default stores), and configure an HTTP server with the content of the configuration.

require 'vertx-config/config_retriever'
retriever = VertxConfig::ConfigRetriever.create($vertx)
retriever.get_config() { |json_err,json|
  result = json

  $vertx.create_http_server().request_handler() { |req|
    result['message']
  }.listen(result['port'])
}

Configuring a set of verticles

The following example configures 2 verticles using the configurations contained in the verticles.json file:

require 'vertx-config/config_retriever'
retriever = VertxConfig::ConfigRetriever.create(@vertx, {
  'stores' => [
    {
      'type' => "file",
      'config' => {
        'path' => "verticles.json"
      }
    }
  ]
})

retriever.get_config() { |json_err,json|
  a = json['a']
  b = json['b']
  @vertx.deploy_verticle(Java::Examples::GreetingVerticle::class.get_name(), {
    'config' => a
  })
  @vertx.deploy_verticle(Java::Examples::GreetingVerticle::class.get_name(), {
    'config' => b
  })
}

Configuring Vert.x itself

You can also configure Vert.x directly. For this, you need a temporary Vert.x instance used to retrieve the configuration. Then the actual instance is created:

require 'vertx/vertx'
require 'vertx-config/config_retriever'
# Create a first instance of Vert.x
vertx = Vertx::Vertx.vertx()
# Create the config retriever
retriever = VertxConfig::ConfigRetriever.create(vertx, {
  'stores' => [
    {
      'type' => "file",
      'config' => {
        'path' => "vertx.json"
      }
    }
  ]
})

# Retrieve the configuration
retriever.get_config() { |json_err,json|
  result = json
  # Close the vert.x instance, we don't need it anymore.
  vertx.close()

  # Create a new Vert.x instance using the retrieve configuration
  options = result
  newVertx = Vertx::Vertx.vertx(options)

  # Deploy your verticle
  newVertx.deploy_verticle(Java::Examples::GreetingVerticle::class.get_name(), {
    'config' => result['a']
  })
}

Propagating configuration changes to the event bus

Vert.x Config notifies you when the configuration changes. If you want to react to this event, you need to implement the reaction yourself. For instance, you can un-deploy and redeploy verticle or send the new configuration on the event bus. The following example shows this latter case. It sends the new configuration on the event bus. Interested verticles can listen for this address and update themselves:

require 'vertx-config/config_retriever'
retriever = VertxConfig::ConfigRetriever.create(@vertx, {
  'stores' => [
    {
      'type' => "file",
      'config' => {
        'path' => "verticles.json"
      }
    }
  ]
})

retriever.get_config() { |json_err,json|
  #...
}

retriever.listen() { |change|
  json = change['newConfiguration']
  @vertx.event_bus().publish("new-configuration", json)
}

Available configuration stores

The Config Retriever provides a set of configuration stores and formats. More are available as extensions, and you can also implement your own.

Structure of the configuration

Each declared data store must specify the type. It can also define the format. If not set JSON is used.

Some configurations tore requires additional configuration (such a path…​). This configuration is passed as a Json Object using config

File

This configuration store just read the configuration from a file. It supports all supported formats.

file = {
  'type' => "file",
  'format' => "properties",
  'config' => {
    'path' => "path-to-file.properties"
  }
}

The path configuration is required.

JSON

The JSON configuration store serves the given JSON config as it is.

json = {
  'type' => "json",
  'config' => {
    'key' => "value"
  }
}

The only supported format for this configuration store is JSON.

Environment Variables

This configuration store transforms environment variables to a JSON Object contributed to the global configuration.

json = {
  'type' => "env"
}

This configuration store does not support the format configuration. By default, the retrieved value is transformed into JSON compatible structures (number, string, boolean, JSON object and JSON array). To avoid this conversion, configure the raw-data attribute:

json = {
  'type' => "env",
  'config' => {
    'raw-data' => true
  }
}

You can configure the raw-data attribute (false by default). If raw-data is true no attempts to convert values is made, and you’ll be able to get raw values using config.getString(key). It is useful when manipulating large integers.

If you want to select the set of keys to import, use the keys attributes. It filters out all non selected keys. Keys must be listed individually:

json = {
  'type' => "env",
  'config' => {
    'keys' => [
      "SERVICE1_HOST",
      "SERVICE2_HOST"
    ]
  }
}

System Properties

This configuration store transforms system properties to a JSON Object contributed to the global configuration.

json = {
  'type' => "sys",
  'config' => {
    'cache' => "false"
  }
}

This configuration store does not support the format configuration.

You can configure the cache attribute (true by default) let you decide whether or not it caches the system properties on the first access and does not reload them.

You can also configure the raw-data attribute (false by default). If raw-data is true no attempts to convert values is made, and you’ll be able to get raw values using config.getString(key). It is useful when manipulating large integers.

HTTP

This configuration store retrieves the configuration from an HTTP location. It can use any supported format.

http = {
  'type' => "http",
  'config' => {
    'host' => "localhost",
    'port' => 8080,
    'path' => "/A"
  }
}

It creates a Vert.x HTTP Client with the store configuration (see next snippet). To ease the configuration; you can also configure the host, port and path with the host, port and path properties.

http = {
  'type' => "http",
  'config' => {
    'defaultHost' => "localhost",
    'defaultPort' => 8080,
    'ssl' => true,
    'path' => "/A"
  }
}

Event Bus

This event bus configuration store receives the configuration from the event bus. This stores let you distribute your configuration among your local and distributed components.

eb = {
  'type' => "event-bus",
  'config' => {
    'address' => "address-getting-the-conf"
  }
}

This configuration store supports any format.

Directory

This configuration store is similar to the file configuration store, but instead of reading a single file, read several files from a directory.

This configuration store configuration requires:

  • a path - the root directory in which files are located

  • at least one fileset - an object to select the files

  • for properties file, you can indicate if you want to disable the type conversion using the raw-data attribute

Each fileset contains: * a pattern : a Ant-style pattern to select files. The pattern is applied on the relative path of the files from the current working directory. * an optional format indicating the format of the files (each fileset can use a different format, BUT files in a fileset must share the same format).

dir = {
  'type' => "directory",
  'config' => {
    'path' => "config",
    'filesets' => [
      {
        'pattern' => "dir/*json"
      },
      {
        'pattern' => "dir/*.properties",
        'format' => "properties"
      }
    ]
  }
}

dirWithRawData = {
  'type' => "directory",
  'config' => {
    'path' => "config",
    'filesets' => [
      {
        'pattern' => "dir/*json"
      },
      {
        'pattern' => "dir/*.properties",
        'format' => "properties",
        'raw-data' => true
      }
    ]
  }
}

Properties file and raw data

Vert.x Config can read properties file. When reading such a file, you can pass the raw-data attribute to indicate to Vert.x to not attempt to convert values. It is useful when manipulating large integers. Values can be retrieved using config.getString(key).

propertyWithRawData = {
  'format' => "properties",
  'type' => "file",
  'config' => {
    'path' => "raw.properties",
    'raw-data' => true
  }
}

Some properties configuration maybe is hierarchical in nature. When reading such a file, you can pass the hierarchical attribute to indicate to Vert.x to convert the configuration to a json object while maintaining this hierarchy, in contrast to the previous method with a flat structure.

Example:

server.host=localhost
server.port=8080
multiple.values=1,2,3

Get values:

require 'vertx/vertx'
require 'vertx-config/config_retriever'
propertyWitHierarchical = {
  'format' => "properties",
  'type' => "file",
  'config' => {
    'path' => "hierarchical.properties",
    'hierarchical' => true
  }
}
options = {
  'stores' => [
    propertyWitHierarchical
  ]
}

configRetriever = VertxConfig::ConfigRetriever.create(Vertx::Vertx.vertx(), options)

configRetriever.config_stream().handler() { |config|
  host = config['server']['host']
  port = config['server']['port']
  multiple = config['multiple']['values']
  (0...multiple.length).each do |i|
    value = multiple[i]
  end
}

Listening for configuration changes

The Configuration Retriever periodically retrieve the configuration, and if the outcome is different from the current one, your application can be reconfigured. By default, the configuration is reloaded every 5 seconds.

require 'vertx/vertx'
require 'vertx-config/config_retriever'
options = {
  'scanPeriod' => 2000,
  'stores' => [
    store1,
    store2
  ]
}

retriever = VertxConfig::ConfigRetriever.create(Vertx::Vertx.vertx(), options)
retriever.get_config() { |json_err,json|
  # Initial retrieval of the configuration
}

retriever.listen() { |change|
  # Previous configuration
  previous = change['previousConfiguration']
  # New configuration
  conf = change['newConfiguration']
}

Retrieving the last retrieved configuration

You can retrieve the last retrieved configuration without "waiting" to be retrieved using:

last = retriever.get_cached_config()

Reading configuration as a stream

The ConfigRetriever provide a way to access the stream of configuration. It’s a ReadStream of JsonObject. By registering the right set of handlers you are notified:

  • when a new configuration is retrieved

  • when an error occur while retrieving a configuration

  • when the configuration retriever is closed (the endHandler is called).

require 'vertx/vertx'
require 'vertx-config/config_retriever'
options = {
  'scanPeriod' => 2000,
  'stores' => [
    store1,
    store2
  ]
}

retriever = VertxConfig::ConfigRetriever.create(Vertx::Vertx.vertx(), options)
retriever.config_stream().end_handler() { |v|
  # retriever closed
}.exception_handler() { |t|
  # an error has been caught while retrieving the configuration
}.handler() { |conf|
  # the configuration
}

Processing the configuration

You can configure a processor that can validate and update the configuration. This is done using the setConfigurationProcessor method.

The prcessing must not return null. It takes the retrieved configuration and returns the processed one. If the processor does not update the configuration, it must return the input configuration. If the processor can throw an exception (for example for validation purpose).

Retrieving the configuration as a Future

The ConfigRetriever provide a way to retrieve the configuration as a Future:

require 'vertx-config/config_retriever'
future = VertxConfig::ConfigRetriever.get_config_as_future(retriever)
future.set_handler() { |ar_err,ar|
  if (ar_err != nil)
    # Failed to retrieve the configuration
  else
    config = ar
  end
}

Extending the Config Retriever

You can extend the configuration by implementing:

  • the ConfigProcessor SPI to add support for a format

  • the ConfigStoreFactory SPI to add support for configuration store (place from where the configuration data is retrieved)

Additional formats

Besides of the out of the box format supported by this library, Vert.x Config provides additional formats you can use in your application.

Unresolved directive in index.adoc - include::hocon-format.adoc[]

Unresolved directive in index.adoc - include::yaml-format.adoc[]

Additional stores

Besides of the out of the box stores supported by this library, Vert.x Config provides additional stores you can use in your application.

Unresolved directive in index.adoc - include::git-store.adoc[]

Unresolved directive in index.adoc - include::kubernetes-store.adoc[]

Unresolved directive in index.adoc - include::redis-store.adoc[]

Unresolved directive in index.adoc - include::zookeeper-store.adoc[]

Unresolved directive in index.adoc - include::consul-store.adoc[]

Unresolved directive in index.adoc - include::spring-store.adoc[]

Unresolved directive in index.adoc - include::vault-store.adoc[]