- `onlyMarketplaceExtensions` allows or blocks developers from installing other extensions by using the command line. Teams developing new extensions must have this setting unlocked (`"locked": false`) to install and test extensions being developed.
- `extensionsPrivateMarketplaceAdminContactURL` defines a contact link for developers to request new extensions in the private marketplace. If `value` is empty then no link is shown to your developers on Docker Desktop, otherwise this can be either an HTTP link or a “mailto:” link. For example,

  ```json
  "extensionsPrivateMarketplaceAdminContactURL": {
    "locked": true,
    "value": "mailto:admin@acme.com"
  }
  ```

To find out more information about the `admin-settings.json` file, see [Settings Management](/manuals/security/for-admins/hardened-desktop/settings-management/_index.md).

## Step three: List allowed extensions

The generated `extensions.txt` file defines the list of extensions that are available in your private marketplace.

Each line in the file is an allowed extension and follows the format of `org/repo:tag`.

For example, if you want to permit the Disk Usage extension you would enter the following into your `extensions.txt` file:

```console
docker/disk-usage-extension:0.2.8
```

If no tag is provided, the latest tag available for the image is used. You can also comment out lines with `#` so the extension is ignored.

This list can include different types of extension images:

- Extensions from the public marketplace or any public image stored in Docker Hub.
- Extension images stored in Docker Hub as private images. Developers need to be signed in and have pull access to these images.
- Extension images stored in a private registry. Developers need to be signed in and have pull access to these images.

> [!IMPORTANT]
>
> Your developers can only install the version of the extension that you’ve listed.

## Step four: Generate the private marketplace

Once the list in `extensions.txt` is ready, you can generate the marketplace:

{{< tabs group="os_version" >}}
{{< tab name="Mac" >}}

```console
$ /Applications/Docker.app/Contents/Resources/bin/extension-admin generate
```

{{< /tab >}}
{{< tab name="Windows" >}}

```console
$ C:\Program Files\Docker\Docker\resources\bin\extension-admin generate
```

{{< /tab >}}
{{< tab name="Linux" >}}

```console
$ /opt/docker-desktop/extension-admin generate
```

{{< /tab >}}
{{< /tabs >}}

This creates an `extension-marketplace` directory and downloads the marketplace metadata for all the allowed extensions.

The marketplace content is generated from extension image information as image labels, which is the [same format as public extensions](extensions-sdk/extensions/labels.md). It includes the extension title, description, screenshots, links, etc.