Gradle Download Task

This is a download task for Gradle. It displays progress information just as Gradle does when it retrieves an artifact from a repository.

The plugin has been successfully tested with Gradle 2.0 up to 6.4. It should work with newer versions as well.

Apply plugin configuration

Gradle 2.1 and higher

plugins {
    id "de.undercouch.download" version "4.0.4"
}

Gradle 2.0

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'de.undercouch:gradle-download-task:4.0.4'
    }
}

apply plugin: 'de.undercouch.download'

Usage

After you have applied the plugin configuration (see above), you can use the Download task as follows:

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest buildDir
}

By default, the plugin always performs a download even if the destination file already exists. If you want to prevent files from being downloaded again, use the overwrite flag (see description below).

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest buildDir
    overwrite false
}

As an alternative to the Download task, you may also use the download extension to retrieve a file anywhere in your build script:

task myTask {
    doLast {
        //do something ...
        //... then download a file
        download {
            src 'http://www.example.com/index.html'
            dest buildDir
            overwrite false
        }
        //... do something else
    }
}

Minimum requirements

The plugin requires:

• Gradle 2.x or higher
• Java 7 or higher

If you need to run the plugin with Gradle 1.x or Java 6, use gradle-download-task version 3.4.3.

Examples

Only download a file if it has been modified on the server

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest buildDir
    onlyIfModified true
}

Note that this feature depends on the server and whether it supports the If-Modified-Since request header and provides a Last-Modified timestamp in its response.

Sequentially download a list of files to a directory

task downloadMultipleFiles(type: Download) {
    src([
        'http://www.example.com/index.html',
        'http://www.example.com/test.html'
    ])
    dest buildDir
}

Please note that you have to specify a directory as destination if you download multiple files. Otherwise, the plugin will fail.

Download files from a directory

If you want to download all files from a directory and the server provides a simple directory listing, you can use the following code:

task downloadDirectory {
    doLast {
        def dir = 'http://central.maven.org/maven2/de/undercouch/gradle-download-task/1.0/'
        def urlLister = new org.apache.ivy.util.url.ApacheURLLister()
        def files = urlLister.listFiles(new URL(dir))
        download {
           src files
           dest buildDir
        }
    }
}

Download and extract a ZIP file

To download and unpack a ZIP file, you can combine the download task plugin with Gradle's built-in support for ZIP files:

task downloadZipFile(type: Download) {
    src 'https://github.com/michel-kraemer/gradle-download-task/archive/1.0.zip'
    dest new File(buildDir, '1.0.zip')
}

task downloadAndUnzipFile(dependsOn: downloadZipFile, type: Copy) {
    from zipTree(downloadZipFile.dest)
    into buildDir
}

More examples

Please have a look at the examples directory for more code samples. You can also read my blog post about common recipes for gradle-download-task.

Download task

The download task and the extension support the following properties.

General

src

The URL from which to retrieve the file. Can be a list of URLs if multiple files should be downloaded. (required)

dest

The file or directory where to store the file (required)

quiet

true if progress information should not be displayed (default: false)

overwrite

true if existing files should be overwritten (default: true)

onlyIfModified (alias: onlyIfNewer)

true if the file should only be downloaded if it has been modified on the server since the last download (default: false)

Tip! You may provide Groovy Closures to the src and dest properties to calculate their value at runtime.

Connection

acceptAnyCertificate

true if HTTPS certificate verification errors should be ignored and any certificate (even an invalid one) should be accepted. (default: false)

compress

true if compression should be used during download (default: true)

header

The name and value of a request header to set when making the download request (optional)

headers

A map of request headers to set when making the download request (optional)

connectTimeout

The maximum number of milliseconds to wait until a connection is established. A value of 0 (zero) means infinite timeout. A negative value is interpreted as undefined. (default: 30 seconds)

readTimeout

The maximum time in milliseconds to wait for data from the server. A value of 0 (zero) means infinite timeout. A negative value is interpreted as undefined. (default: 30 seconds)

retries

Specifies the maximum number of retry attempts if a request has failed. By default, requests are never retried and the task fails immediately if the first request does not succeed. If the value is greater than 0, failed requests are retried regardless of the actual error. This includes failed connection attempts and file-not-found errors (404). A negative value means infinite retries. (default: 0)

Authentication

username

The username for Basic or Digest authentication (optional)

password

The password for Basic or Digest authentication (optional)

authScheme

The authentication scheme to use (valid values are Basic and Digest). If username and password are set, the default value of this property will be Basic. Otherwise, this property has no default value. (optional)

Advanced

downloadTaskDir

The directory where the plugin stores information that should persist between builds. It will only be created if necessary. (default: ${buildDir}/download-task)

tempAndMove

true if the file should be downloaded to a temporary location and, upon successful execution, moved to the final location. If overwrite is set to false, this flag is useful to avoid partially downloaded files if Gradle is forcefully closed or the system crashes. Note that the plugin always deletes partial downloads on connection errors, regardless of the value of this flag. The default temporary location can be configured with the downloadTaskDir property. (default: false)

useETag

Use this flag in combination with onlyIfModified. If both flags are true, the plugin will check a file's timestamp as well as its entity tag (ETag) and only download it if it has been modified on the server since the last download. The plugin can differentiate between strong and weak ETags. Possible values are:

false (default)

Do not use the ETag

true

Use the ETag but display a warning if it is weak

"all"

Use the ETag and do not display a warning if it is weak

"strongOnly"

Only use the ETag if it is strong

cachedETagsFile

The location of the file that keeps entity tags (ETags) received from the server. (default: ${downloadTaskDir}/etags.json)

Verify task

The plugin also provides a Verify task that can be used to check the integrity of a downloaded file by calculating its checksum and comparing it to a pre-defined value. The task succeeds if the file's checksum equals the given value and fails if it doesn't.

Use the task as follows:

task verifyFile(type: Verify) {
    src new File(buildDir, 'file.ext')
    algorithm 'MD5'
    checksum 'ce114e4501d2f4e2dcea3e17b546f339'
}

You can combine the download task and the verify task as follows:

task downloadFile(type: Download) {
    src 'http://www.example.com/index.html'
    dest buildDir
}

task verifyFile(type: Verify, dependsOn: downloadFile) {
    src new File(buildDir, 'index.html')
    algorithm 'MD5'
    checksum '09b9c392dc1f6e914cea287cb6be34b0'
}

The verify task supports the following properties:

src

The file to verify (required)

checksum

The actual checksum to verify against (required)

algorithm

The algorithm to use to compute the checksum. See the list of algorithm names for more information. (default: MD5)

Proxy configuration

You can configure a proxy server by setting standard JVM system properties. The plugin uses the same system properties as Gradle. You can set them in the build script directly. For example, the proxy host can be set as follows:

System.setProperty("http.proxyHost", "www.somehost.org");

Alternatively, you can set the properties in a gradle.properties file like this:

systemProp.http.proxyHost=www.somehost.org
systemProp.http.proxyPort=8080
systemProp.http.proxyUser=userid
systemProp.http.proxyPassword=password
systemProp.http.nonProxyHosts=*.nonproxyrepos.com|localhost

Put this file in your project's root directory or in your Gradle home directory.

HTTPS is also supported:

systemProp.https.proxyHost=www.somehost.org
systemProp.https.proxyPort=8080
systemProp.https.proxyUser=userid
systemProp.https.proxyPassword=password
systemProp.https.nonProxyHosts=*.nonproxyrepos.com|localhost

Migrating from version 3.x to 4.x

In gradle-download-task 4.x, we made the following breaking changes to the API:

• The plugin now requires Gradle 2.x (or higher) and Java 7 (or higher)
• We removed the timeout property and introduced connectTimeout and readTimeout instead. This allows you to control the individual timeouts better. Also, it improves compatibility with Gradle 5.x, where all tasks have a timeout property by default.
• The credentials property has been removed. The same applies to the possibility to pass instances of Apache HttpClient's AuthScheme to the authScheme property. The strings Basic and Digest are now the only accepted values. There is no replacement. If you need this functionality, please file an issue.
• The properties requestInterceptor and responseInterceptor have been removed. There is no replacement. Again, if you need this functionality, please file an issue.

License

The plugin is licensed under the Apache License, Version 2.0.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.