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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 (files, directories, http, git (extension), redis (extension), system properties, 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 and a syntax (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>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'

Once done, you first need to instantiate the ConfigRetriever:

def retriever = 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

You can configure your own stores:

def httpStore = [
  type:"http",
  config:[
    host:"localhost",
    port:8080,
    path:"/conf"
  ]
]

def fileStore = [
  type:"file",
  config:[
    path:"my-config.json"
  ]
]

def sysPropsStore = [
  type:"sys"
]


def options = [
  stores:[
    httpStore,
    fileStore,
    sysPropsStore
  ]
]

def retriever = ConfigRetriever.create(vertx, options)

More details about the overloading rules and available stores are available below.

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

retriever.getConfig({ ar ->
  if (ar.failed()) {
    // Failed to retrieve the configuration
  } else {
    def config = ar.result()
  }
})

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 would get: * {a:value, b:1, c:2}.

Available configuration stores

The Config Retriever provides a set of configuration store and format. Some more are available as extension and you can 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 setConfig

File

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

def file = [
  type:"file",
  format:"properties",
  config:[
    path:"path-to-file.properties"
  ]
]

The path configuration is required.

JSON

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

def json = [
  type:"json",
  config:[
    key:"value"
  ]
]

The only supported format for this configuration store is JSON.

Environment Variables

This configuration store maps environment variables to a Json Object contributed to the global configuration.

def json = [
  type:"env"
]

This configuration store does not support the format configuration.

System Properties

This configuration store maps system properties to a Json Object contributed to the global configuration.

def 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.

HTTP

This configuration stores retrieves the configuration from a HTTP location. It can use any supported format.

def 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.

def http = [
  type:"http",
  config:[
    defaultHost:"localhost",
    defaultPort:8080,
    ssl:true,
    path:"/A"
  ]
]

Event Bus

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

def eb = [
  type:"event-bus",
  config:[
    address:"address-getting-the-conf"
  ]
]

This configuration store supports any type of 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

Each fileset contains: * a pattern : a Ant style pattern to select files. The pattern is applied on the relative path of the files location in the 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).

def dir = [
  type:"directory",
  config:[
    path:"config",
    filesets:[
      [
        pattern:"dir/*json"
      ],
      [
        pattern:"dir/*.properties",
        format:"properties"
      ]
    ]
  ]
]

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.

def options = [
  scanPeriod:2000,
  stores:[
    store1,
    store2
  ]
]

def retriever = ConfigRetriever.create(Vertx.vertx(), options)
retriever.getConfig({ json ->
  // Initial retrieval of the configuration
})

retriever.listen({ change ->
  // Previous configuration
  def previous = change.previousConfiguration
  // New configuration
  def conf = change.newConfiguration
})

Retrieving the last retrieved configuration

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

def last = retriever.getCachedConfig()

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).

def options = [
  scanPeriod:2000,
  stores:[
    store1,
    store2
  ]
]

def retriever = ConfigRetriever.create(Vertx.vertx(), options)
retriever.configStream().endHandler({ v ->
  // retriever closed
}).exceptionHandler({ t ->
  // an error has been caught while retrieving the configuration
}).handler({ conf ->
  // the configuration
})

Retrieving the configuration as a Future

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

def future = ConfigRetriever.getConfigAsFuture(retriever)
future.setHandler({ ar ->
  if (ar.failed()) {
    // Failed to retrieve the configuration
  } else {
    def config = ar.result()
  }
})

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

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

Hocon Configuration Format

The Hocon Configuration Format extends the Vert.x Configuration Retriever and provides the support for the HOCON(https://github.com/typesafehub/config/blob/master/HOCON.md) format.

It supports includes, json, properties, macros…​

Using the Hocon Configuration Format

To use the Hocon Configuration Format, 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-hocon</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-hocon:3.4.1'

Configuring the store to use HOCON

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this format:

def store = [
  type:"file",
  format:"hocon",
  config:[
    path:"my-config.conf"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

You just need to set format to hocon.

Yaml Configuration Format

The Yaml Configuration Format extends the Vert.x Configuration Retriever and provides the support for the Yaml Configuration Format format.

Using the Yaml Configuration Format

To use the Yaml Configuration Format, 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-yaml</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-yaml:3.4.1'

Configuring the store to use YAML

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this format:

def store = [
  type:"file",
  format:"yaml",
  config:[
    path:"my-config.yaml"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

You just need to set format to yaml.

Additional stores

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

Git Configuration Store

The Git Configuration Store is an extension to the Vert.x Configuration Retriever to retrieve configuration from a Git repository.

Using the Git Configuration Store

To use the Git Configuration, 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-git</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-git:3.4.1'

Configuring the store

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this store:

def git = [
  type:"git",
  config:[
    url:"https://github.com/cescoffier/vertx-config-test.git",
    path:"local",
    filesets:[
      [
        pattern:"*.json"
      ]
    ]
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    git
  ]
])

The configuration requires:

  • the url of the repository

  • the path where the repository is cloned (local directory)

  • at least fileset indicating the set of files to read (same behavior as the directory configuration store).

You can also configure the branch (master by default) to use and the name of the remote repository (origin by default).

How does it works

If the local path does not exist, the configuration store clones the repository into this directory. Then it reads the file matching the different file sets.

It the local path exist, it tried to update it (it switches branch if needed)). If the update failed the configuration retrieval fails.

Periodically, the repositories is updated to check if the configuration has been updated.

Kubernetes ConfigMap Store

The Kubernetes ConfigMap Store extends the Vert.x Configuration Retriever and provides the support Kubernetes Config Map and Secrets.

So, configuration is retrieved by reading the config map or the secrets.

Using the Kubernetes ConfigMap Store

To use the Kubernetes ConfigMap Store, 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-kubernetes-configmap</artifactId>
<version>3.4.1</version>
</dependency>
<dependency>
<groupId>io.vertx</groupId>
<artifactId>vertx-config</artifactId>
<version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-kubernetes-configmap:3.4.1'

Configuring the store

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this store:

def store = [
  type:"configmap",
  config:[
    namespace:"my-project-namespace",
    name:"configmap-name"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

You need to configure the store to find the right configmap. this is done with:

  • namespace - the project namespace, default by default. If the KUBERNETES_NAMESPACE ENV variable is set, it uses this value.

  • name - the name of the config map

If the config map is composed by several element, you can use the key parameter to tell which key is read

The application must have the permissions to read the config map.

To read data from a secret, just configure the secret property to true:

def store = [
  type:"configmap",
  config:[
    namespace:"my-project-namespace",
    name:"my-secret",
    secret:true
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

Redis Configuration Store

The Redis Configuration Store extends the Vert.x Configuration Retriever and provides the way to retrieve configuration from a Redis server.

Using the Redis Configuration Store

To use the Redis Configuration Store, 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-redis</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-redis:3.4.1'

Configuring the store

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this store:

def store = [
  type:"redis",
  config:[
    host:"localhost",
    port:6379,
    key:"my-configuration"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

The store configuration is used to create an instance of RedisClient. check the documentation of the Vert.x Redis Client for further details.

In addition, you can set the key instructing the store in which field the configuration is stored. configuration is used by default.

The created Redis client retrieves the configuration using the HGETALL configuration.

Zookeeper Configuration Store

The Zookeeper Configuration Store extends the Vert.x Configuration Retriever and provides the way to retrieve configuration from a Zookeeper server.

It uses Apache Curator as client.

Using the Zookeeper Configuration Store

To use the Redis Configuration Store, 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-zookeeper</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-zookeeper:3.4.1'

Configuring the store

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this store:

def store = [
  type:"zookeeper",
  config:[
    connection:"localhost:2181",
    path:"/path/to/my/conf"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

The store configuration is used to configure the Apache Curator client and the path of the Zookeeper node containing the configuration. Notice that the format of the configuration can be JSON, or any supported format.

The configuration requires the configuration attribute indicating the connection string of the Zookeeper server, and the path attribute indicating the path of the node containing the configuration.

In addition you can configure:

  • maxRetries: the number of connection attempt, 3 by default

  • baseSleepTimeBetweenRetries: the amount of milliseconds to wait between retries (exponential backoff strategy). 1000 ms by default.

Spring Config Server Store

The Spring Config Server Store extends the Vert.x Configuration Retriever and provides the a way to retrieve configuration from a Spring Server.

Using the Spring Config Server Store

To use the Spring Config Server Store, 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-spring-config-server</artifactId>
  <version>3.4.1</version>
</dependency>
<dependency>
  <groupId>io.vertx</groupId>
  <artifactId>vertx-config</artifactId>
  <version>3.4.1</version>
</dependency>
  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-config:3.4.1'
compile 'io.vertx:vertx-config-spring-config-server:3.4.1'

Configuring the store

Once added to your classpath or dependencies, you need to configure the ConfigRetriever to use this store:

def store = [
  type:"spring-config-server",
  config:[
    url:"http://localhost:8888/foo/development"
  ]
]

def retriever = ConfigRetriever.create(vertx, [
  stores:[
    store
  ]
])

Configurable attributes are:

  • url - the url to retrieve the configuration (mandatory)

  • timeout - the timeout (in milliseconds) to retrieve the configuration, 3000 by default

  • user - the user (no authentication by default)

  • password - the password

  • httpClientConfiguration - the configuration of the underlying HTTP client