Docker Performance Settings (WSL 2 backend and the daemon)

Docker WSL 2 Configuration This is the easiest thing to get wrong on Windows: under the WSL 2 backend, Docker’s CPU and memory are not set in the Docker Desktop GUI; they are controlled by the WSL 2 utility VM’s config file.

Connecting to the WSL 2 backend

Docker Desktop → Settings → General → check Use the WSL 2 based engine.
Settings → Resources → WSL Integration → enable the distros where you want docker available (such as Ubuntu) → Apply & Restart.

With integration on, you can use docker directly from that distro’s Linux terminal.

Only the Hyper-V backend (or macOS / Linux) sets CPU / memory / swap directly under Docker Desktop’s Settings → Resources → Advanced. The WSL 2 backend uses .wslconfig below.

Allocating resources (`.wslconfig`)

CPU / memory / swap are set in the [wsl2] section of %UserProfile%\.wslconfig (create the file if missing). The [wsl2] section header is mandatory, or the settings are ignored:

# Path: C:\Users\<your-username>\.wslconfig
[wsl2]
memory=8GB       # WSL 2 VM memory cap (default is 50% of physical RAM)
processors=4     # virtual processors available (default equals logical processor count)
swap=8GB         # swap size (0 to disable)
# swapfile=C:\\WSL\\wsl-swap.vhdx   # swap file location (default %Temp%\swap.vhdx)

[experimental]
autoMemoryReclaim=dropCache   # automatically release idle memory
sparseVhd=true                # auto-sparsify new VHDs to save real disk usage

Restart WSL to apply:

wsl --shutdown          # shut down all WSL distros (about 8s to fully stop)
wsl --list --running    # confirm none are still running
wsl -d Ubuntu           # start again, settings now applied

Common WSL integration commands

wsl -l -v                       # list distros, WSL version (1 or 2), and state
wsl --set-default-version 2     # new distros default to WSL 2
wsl --set-version Ubuntu 2      # convert an existing distro to WSL 2
wsl --update                    # update the WSL kernel
wsl --shutdown                  # shut down all WSL (required to apply .wslconfig)
wsl --terminate Ubuntu          # shut down only one distro, leaving others running
wsl --status                    # WSL version and kernel info

Where Docker data lives and how to check its size

Under the WSL 2 backend, Docker’s image layers, containers, and volume data all live in the virtual disk (VHDX) of the docker-desktop-data WSL distro, by default at:

C:\Users\<UserName>\AppData\Local\Docker\wsl\

wsl -l -v        # you will see both docker-desktop and docker-desktop-data

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

The docker-desktop-data VHDX is the source of disk usage. It grows dynamically but does not shrink back automatically, and File Explorer does not show its real usage; check with a command:

Get-ChildItem "$env:LOCALAPPDATA\Docker\wsl" -Recurse -File |
  Select-Object Name, @{N='Size(MB)';E={[math]::Round($_.Length/1MB,1)}}

Reclaim space via the cleanup commands (docker system prune). To move the VHDX: Docker Desktop → Settings → Resources → Advanced → Disk image location.

daemon.json (Docker engine settings)

To tune registry mirrors, log rotation, default runtime, and other engine-level settings, edit the daemon config. On Docker Desktop you do not edit the file directly; use the JSON editor under Settings → Docker Engine. Only native Linux installs use /etc/docker/daemon.json.

{
  "log-driver": "json-file",
  "log-opts": { "max-size": "10m", "max-file": "3" },
  "registry-mirrors": ["https://mirror.example.com"],
  "default-runtime": "runc",
  "live-restore": true
}

Common keys: log-opts caps per-container log size and file count (worth adding by default so logs do not fill the disk), registry-mirrors speeds up pulls, data-root changes the data root, live-restore keeps containers running across a daemon restart.

Where data lives: volume vs bind mount performance on WSL 2.
Docker CLI commands: cleanup commands to reclaim VHDX space.

Reference: docs.docker.com/desktop/features/wsl, learn.microsoft.com/windows/wsl/wsl-config

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Networking & Self-hosting

Docker Performance Settings (WSL 2 backend and the daemon)

Connecting to the WSL 2 backend

Allocating resources (`.wslconfig`)

Common WSL integration commands

Where Docker data lives and how to check its size

daemon.json (Docker engine settings)

Next

​Connecting to the WSL 2 backend

​Allocating resources (.wslconfig)

​Common WSL integration commands

​Where Docker data lives and how to check its size

​daemon.json (Docker engine settings)

​Next

Connecting to the WSL 2 backend

Allocating resources (`.wslconfig`)

Common WSL integration commands

Where Docker data lives and how to check its size

daemon.json (Docker engine settings)

Next