Spring Initializr

Spring Initializr provides an extensible API to generate quickstart projects. It also provides a configurable service (you can see our default instance at https://start.spring.io). It provides a simple web UI to configure the project to generate and endpoints that you can use via plain HTTP.

Spring Initializr also exposes an endpoint that serves its metadata in a well-known format to allow third-party clients to provide the necessary assistance.

Finally, Initializr offers a configuration structure to define all the aspects related to the project to generate: list of dependencies, supported java and boot versions, etc. Check the companion project that defines https://start.spring.io and, in particular, the configuration of our instance for an example. Such configuration is also described in details in the documentation.

Note	Check the milestones page for an overview of the changes.

Installation and Getting Started

The reference documentation is available in HTML format.

Modules

Spring Initializr has the following modules:

• initializr-generator: core project generation library

• initializr-metadata: metadata infrastructure for various aspects of the project

• initializr-generator-spring: optional module defining the conventions for a Spring Boot project. Can be replaced by your own conventions if necessary.

• initializr-web: REST endpoints and web interface

• initializr-actuator: optional module to provide additional information and statistics on project generation

• initializr-docs: documentation

Supported interfaces

Spring Initializr can be used as follows:

• With your browser (i.e. https://start.spring.io)

• In your IDE if you are using STS, IntelliJ IDEA Ultimate or NetBeans (with this plugin)

• On the command-line with the Spring Boot CLI or simply with cURL or HTTPie

Tip	You can "curl" an instance to get a usage page with examples (try curl https://start.spring.io)

Generating a project

If you click on "Generate Project" on the web ui of our instance, it will download a project archive with a Maven-based project and the necessary infrastructure to start a basic Spring Boot app.

You could achieve the same result with a simple curl command

$ curl https://start.spring.io/starter.zip -o demo.zip

The web ui exposes a bunch of options that you can configure. These are mapped to the following request attributes:

• Basic information for the generated project: groupId, artifactId, version, name, description and packageName

  • The name attribute is also used to generate a default application name. The logic is that the name of the application is equal to the name attribute with an Application suffix (unless said suffix is already present). Of course, if the specified name contains an invalid character for a java identifier, Application is used as fallback.

  • The artifactId attribute not only defines the identifier of the project in the build but also the name of the generated archive.

• dependencies (or style): the identifiers of the dependencies to add to the project. Such identifiers are defined through configuration and are exposed in the metadata.

• type: the kind of project to generate (e.g. maven-project). Again, each service exposes an arbitrary number of supported types and these are available in the metadata.

• javaVersion: the language level (e.g. 1.8).

• bootVersion: the Spring Boot version to use (e.g. 1.2.0.RELEASE).

• language: the programming language to use (e.g. java).

• packaging: the packaging of the project (e.g. jar).

• applicationName: the name of the application class (inferred by the name attribute by default).

• baseDir: the name of the base directory to create in the archive. By default, the project is stored in the root.

This command generates an another-project directory holding a Gradle web-based Groovy project using the actuator:

$ curl https://start.spring.io/starter.tgz -d dependencies=web,actuator \
-d language=groovy -d type=gradle-project -d baseDir=another-project | tar -xzvf -

Note	The /starter.tgz endpoint offers the same feature as /starter.zip but generates a compressed tarball instead.

You could use this infrastructure to create your own client since the project is generated via a plain HTTP call.

Customize form inputs

You can share or bookmark URLs that will automatically customize form inputs. For instance, the following URL from the default instance uses groovy by default and set the name to Groovy Sample:

https://start.spring.io/#!language=groovy&name=Groovy%20Sample

The following hashbang parameters are supported: type, groupId, artifactId, name, description, packageName, packaging, javaVersion and language. Review the section above for a description of each of them.

Service metadata

The service metadata is used by the web UI and is exposed to ease the creation of third-party clients. You can grab the metadata by curling the root

$ curl -H 'Accept: application/json' https://start.spring.io

Note	As stated above, if you use curl without an accept header, you’ll retrieve a human readable text version of the metadata. HTTPie is also supported:

$ http https://start.spring.io Accept:application/json

The metadata basically lists the capabilities of the service, that is the available options for all request parameters (dependencies, type, bootVersion, etc.) The web UI uses that information to initialize the select options and the tree of available dependencies.

The metadata also lists the default values for simple text parameter (i.e. the default name for the project).

Note	More details about the structure of the metadata are available in the documentation.

Running your own instance

You can easily run your own instance. The initializr-web modules uses Spring Boot so when it is added to a project, it will trigger the necessary auto-configuration to deploy the service.

You first need to create or update your configuration to define the necessary attributes that your instance will use. Again, check the documentation for a description of the configuration and review our own config for a sample.

You can integrate the library in a traditional Java-based project or by writing the super-simple script below:

package org.acme.myapp

@Grab('io.spring.initializr:initializr-web:1.0.0.BUILD-SNAPSHOT')
@Grab('spring-boot-starter-web')
class YourInitializrApplication { }

Note	Spring Initializr is not available on Maven central yet so you will have to build it from source in order to use it in your own environment.

Once you have created that script (my-instance.groovy), place your configuration in the same directory and simply execute this command to start the service:

$ spring run my-instance.groovy

You may also want to run the default instance locally.

Building from Source

You need Java 1.8 and a bash-like shell.

Building

Just invoke the build at the root of the project

$ ./mvnw clean install

To generate the docs as well, you should enable the full profile:

$ ./mvnw clean install -Pfull

License

Spring Initializr is Open Source software released under the Apache 2.0 license.