Windows Docker Installation and Storage Migration

11/10/2023 713 words About 4 min

Docker Desktop is the common GUI client for Docker on Windows, but its installation and storage settings are not very transparent by default.

This post summarizes practical steps to change the Docker Desktop install path, migrate WSL distributions, and move Docker data storage to reduce C drive pressure.

Changing Docker Desktop Installation Directory

First, download Docker Desktop. In fact, the official Docker documentation explains how to manually set its installation directory. However, when searching online, I found that very few sources mention this—I actually stumbled upon it in a reply under a Zhihu post. Many online tutorials suggest "swapping" its installation path by creating symbolic links; I have not tried this method and do not know how reliable it is. The official method, however, works perfectly.

The official approach is to install via the command line. So after downloading the official installer .exe, do not rush to double-click and open it. Open CMD and navigate to the directory where your installer is located. The command-line installation supports various flags for configuration (I'm not sure why basic features like changing installation paths or setting download proxies are not exposed in the GUI). Here is the command to change the installation path:

1	`"Docker Desktop Installer.exe" install --installation-dir=<installation_directory>`

If you are using PowerShell, the command is as follows:

1	`Start-Process 'Docker Desktop Installer.exe' -Wait install --installation-dir=<installation_directory>`

For other parameter commands, check the Official Manual.

Changing WSL System Directory

Windows places the virtual disk environment for WSL (Windows Subsystem for Linux) on drive C by default. Consequently, Docker's storage directory when using WSL is also located on drive C, typically at: C:\Users\<Username>\AppData\Local\Docker\wsl\data\ext4.vhdx. If it is Docker's WSL directory, you can actually configure it during installation using the command-line parameters mentioned above. If it is already installed, it can still be moved, and this method applies to changing the directory of any WSL subsystem.

First, use wsl --list -v to view the installed distributions and their status, for example:

  NAME                   STATE           VERSION
* Arch                   Running         2
  docker-desktop         Stopped         2
  docker-desktop-data    Stopped         2
  Ubuntu                 Stopped         2

Remember the version number (VERSION) of the distro you want to move. If it is currently running, shut it down using wsl --shutdown. Here, we take moving Docker's system data as an example. What we need to move is the docker-desktop-data distro (Please note: do NOT modify the docker-desktop distro!).

First, back up the distro that needs to be moved.
1

wsl --export docker-desktop-data "<directory_to_save_backup_tar(arbitrary)>\docker-desktop-data.tar"
This step packs the entire distro into a temporary archive, which will later be used to restore the system.
Then, unregister the distro at its original location.
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wsl --unregister docker-desktop-data

Finally, specify the new target directory and restore the backed-up distro:

1	`wsl --import docker-desktop-data "<target_directory_to_move_to>" "<directory_where_backup_tar_was_saved>\docker-desktop-data.tar" --version <VERSION_number_checked_earlier>`

Once finished, the directory migration is complete—finally freeing up the system drive Ꮚ･ꈊ･Ꮚ.