# Chapter 37. Publishing artifacts

## 37.1. Introduction

This chapter is about how you declare the outgoing artifacts of your project, and how to work with them (e.g. upload them). We define the artifacts of the projects as the files the project provides to the outside world. This might be a library or a ZIP distribution or any other file. A project can publish as many artifacts as it wants.

## 37.2. Artifacts and configurations

Like dependencies, artifacts are grouped by configurations. In fact, a configuration can contain both artifacts and dependencies at the same time.

For each configuration in your project, Gradle provides the tasks `upload`ConfigurationName`` and `build`ConfigurationName``. [16] Execution of these tasks will build or upload the artifacts belonging to the respective configuration.

Table Table 20.5, “Java plugin - dependency configurations” shows the configurations added by the Java plugin. Two of the configurations are relevant for the usage with artifacts. The `archives` configuration is the standard configuration to assign your artifacts to. The Java plugin automatically assigns the default jar to this configuration. We will talk more about the `runtime` configuration in Section 37.5, “More about project libraries”. As with dependencies, you can declare as many custom configurations as you like and assign artifacts to them.

## 37.3. Declaring artifacts

### 37.3.1. Archive task artifacts

You can use an archive task to define an artifact:

Example 37.1. Defining an artifact using an archive task

`build.gradle`

    task myJar(type: Jar)

    artifacts {
        archives myJar
    }

It is important to note that the custom archives you are creating as part of your build are not automatically assigned to any configuration. You have to explicitly do this assignment.

### 37.3.2. File artifacts

You can also use a file to define an artifact:

Example 37.2. Defining an artifact using a file

`build.gradle`

    def someFile = file('build/somefile.txt')

    artifacts {
        archives someFile
    }

Gradle will figure out the properties of the artifact based on the name of the file. You can customize these properties:

Example 37.3. Customizing an artifact

`build.gradle`

    task myTask(type:  MyTaskType) {
        destFile = file('build/somefile.txt')
    }

    artifacts {
        archives(myTask.destFile) {
            name 'my-artifact'
            type 'text'
            builtBy myTask
        }
    }

## 37.4. Publishing artifacts

We have said that there is a specific upload task for each configuration. But before you can do an upload, you have to configure the upload task and define where to publish the artifacts to. The repositories you have defined (as described in Section 36.6, “Repositories”) are not automatically used for uploading. In fact, some of those repositories allow only for artifact downloading. Here is an example how you can configure the upload task of a configuration:

Example 37.4. Configuration of the upload task

`build.gradle`

    repositories {
        flatDir {
            name "fileRepo"
            dirs "repo"
        }
    }

    uploadArchives {
        repositories {
            add project.repositories.fileRepo
            ivy {
                credentials {
                    username "username"
                    password "pw"
                }
                url "http://repo.mycompany.com"
            }
        }
    }

As you can see, you can either use a reference to an existing repository or create a new repository. As described in Section 36.6.8, “More about Ivy resolvers”, you can use all the Ivy resolvers suitable for the purpose of uploading.

Uploading to a Maven repository is described in Section 38.6, “Interacting with Maven repositories”.

## 37.5. More about project libraries

If your project is supposed to be used as a library, you need to define what are the artifacts of this library and what are the dependencies of these artifacts. The Java plugin adds a `runtime` configuration for this purpose, with the implicit assumption that the `runtime` dependencies are the dependencies of the artifact you want to publish. Of course this is fully customizable. You can add your own custom configuration or let the existing configurations extend from other configurations. You might have different group of artifacts which have a different set of dependencies. This mechanism is very powerful and flexible.

If someone wants to use your project as a library, she simply needs to declare on which configuration of the dependency to depend on. A Gradle dependency offers the `configuration` property to declare this. If this is not specified, the `default` configuration is used (see Section 36.4.10, “Dependency configurations”). Using your project as a library can either happen from within a multi-project build or by retrieving your project from a repository. In the latter case, an ivy.xml descriptor in the repository is supposed to contain all the neccesary information. If you work with Maven repositories you don't have the flexibility as described above. For how to publish to a Maven repository, see the section Section 38.6, “Interacting with Maven repositories”.

[16] To be exact, the Base plugin provides those tasks. This plugin is automatically applied if you use the Java plugin.