Gradle build without internet connection

Issue

How to build the Gradle workspace without an internet connection?
Steps to run the gradlew command using offline mode

Environment

Liferay DXP

Resolution

We have improved the offline support in the most recent release of the DevStudio, however, all of our build tools (Gradle or Maven)) require an internet connection to download the dependencies. Hence, the Liferay workspace build will not work offline.
For debugging purposes, the below attributes help when executing the Gradle tasks to see is there any additional log information getting traced. For example:
- --stacktrace (or even --full-stacktrace) and
- --info (or --debug)
- --offline
  Note: with the third one, you’re asking Gradle to not use the Internet at all. But not sure if the Liferay Plugins respect that or not.
Secondly, the workspace plugin tries to fetch https://releases.liferay.com/tools/workspace/.product_info.json with every run of a Gradle build. This might happens when registering the liferayWorkspace extension on the Settings object:
- WorkspaceExtension _addWorkspaceExtension(Settings settings)
- ProductInfo _getProductInfo(String product)
You might be able to get around this by putting the file into the _workspaceCacheDir ([user.home]/.liferay/workspace)
And, unless the code fetching the URL (DownloadCommand -> HttpUtil) always executes a HEAD request to the given URL to get the Last-Modified header and compare it to the locally cached file.Unfortunately, it seems it does do exactly that, every time:
- https://github.com/liferay/liferay-portal/blob/053984004354b73692dbc66c41ca271ab9c[…]liferay/portal/tools/bundle/support/internal/util/HttpUtil.java

Additional Information

Please Note: The stated procedures and unofficial link involve custom environmental ideas that are beyond the scope of Liferay Support. Please exercise appropriate discretion in the use of this information. For further assistance on the implementation ideas from Liferay, please reach out to our dedicated global service team. Your sales representative is a great resource to discover the connectivity with the GS team to know more about it in detail.

The below unofficial information might help to understand or plan what actions may take to run Gradle build without an internet connection whereas "completely offline build" is not something we support.