From BlenderWiki

Package Manager

The package manager's interface is located in blender's user preferences, under packages.

Repositories

A repository is an collection of packages stored in a repo.json file. Additional repositories may be added by specifying a URL which points to the repository json file. To do this, click the "edit repositories" button under the repository list, then click the plus icon next to the repository list in the resultant dialog.

Repository creation

A repo.json file may be generated from a directory of addons with the ```generate_repository``` script (found here: https://developer.blender.org/diffusion/BPMA/).

Example usage:

 ./generate_repository /path/to/packages --baseurl 'http://localhost/'

This will produce a `repo.json` file in the current directory, which can then be copied to the server. The baseurl is prepended to the filename of each package to form the package's url (so for example, `http://localhost/node_wrangler.py`).

For an explanation of the other options see `generate_repository --help`:

  usage: generate_repository [-h] [-v] [-u BASEURL] [-n NAME] [-o OUTPUT] path

  Generate a blender package repository from a directory of addons

  positional arguments:
    path                  Path to addon directory

  optional arguments:
    -h, --help            show this help message and exit
    -v, --verbose         Increase verbosity (can be used multiple times)
    -u BASEURL, --baseurl BASEURL
                  Component of URL leading up to the package filename.
    -n NAME, --name NAME  Name of repo (defaults to basename of 'path')
    -o OUTPUT, --output OUTPUT
 Directory in which to write repo.json file 

Packages

Packages may be browsed and installed in the *packages* section of the user preferences.

Note: packages with the same name are considered the same package.

Installing

To install a package, click the install button next to a currently uninstalled package. This will download the package and extract the package's file(s) to the appropriate destination(s). If installing would overwrite an existing file, that file is temporarily renamed with a tilde appended to its name (as in, "file" becomes "file~"). If an error occurs during installation, the previous files are moved back in place.

Uninstalling

Likewise, a package may be removed by clicking the uninstall button next to a currently installed package. This removes the files belonging to the package. Note that packages installed outside the user configuration directory (see https://docs.blender.org/manual/en/dev/getting_started/installing/configuration/directories.html) cannot be uninstalled.

Updating

Newer versions of installed packages are be listed in the *Updates* section and can be installed by clicking *Update*. This will replace the old version.

Refreshing

The refresh operator is automatically refreshed when a repository is added or removed a package is installed or uninstalled. To refresh the package list manually, click *Check for updates* under the repository list. This will re-fetch known repositories, and check for new packages which may have appeared on disk.