Project: Podman (App Definition and Development / Application Definition & Image Build)
File: podman-for-windows.md

Podman for Windows ================== While "containers are Linux," Podman also runs on Mac and Windows, where it provides a native CLI and embeds a guest Linux system to launch your containers. This guest is referred to as a Podman machine and is managed with the `podman machine` command. On Windows, each Podman machine is backed by a virtualized Windows Subsystem for Linux (WSLv2) distribution. The podman command can be run directly from your Windows PowerShell (or CMD) prompt, where it remotely communicates with the podman service running in the WSL environment. Alternatively, you can access Podman directly from the WSL instance if you prefer a Linux prompt and Linux tooling. In addition to command-line access, Podman also listens for Docker API clients, supporting direct usage of Docker-based tools and programmatic access from your language of choice. Prerequisites Since Podman uses WSL, you need a recent release of Windows 10 or Windows 11. On x64, WSL requires build 18362 or later, and 19041 or later is required for arm64 systems. Internally, WSL uses virtualization, so your system must support and have hardware virtualization enabled. If you are running Windows on a VM, you must have a VM that supports nested virtualization. It is also recommended to install the modern "Windows Terminal," which provides a superior user experience to the standard PowerShell and CMD prompts, as well as a WSL prompt, should you want it. You can install it by searching the Windows Store or by running the following `winget` command: `winget install Microsoft.WindowsTerminal` Installing Podman -- Installing the Windows Podman client begins by downloading the Podman Windows installer. The Windows installer is built with each Podman release and can be downloaded from the official . Be sure to download a 4.1 or later release for the capabilities discussed in this guide. Once downloaded, simply run the EXE file, and relaunch a new terminal. After this point, podman.exe will be present on your PATH, and you will be able to run the `podman machine init` command to create your first machine. `PS C:\Users\User> podman machine init` Automatic WSL Installation -- If WSL has not been installed on your system, the first machine init command will prompt a dialog to begin an automated install. If accepted, this process will install the necessary Windows components, restart the system, and after login, relaunch the machine creation process in a terminal window. Be sure to wait a minute or two for the relaunch to occur, as Windows has a delay before executing startup items. Alternatively, you can decline automatic installation and install WSL manually. However, this will require additional download and setup time. Machine Init Process -- After WSL is installed, the init command will install a minimal installation of Fedora, customizing it to run

``` PS C:\Users\User> podman machine init Extracting compressed file Importing operating system into WSL (this may take 5+ minutes on a new WSL install)... Installing packages (this will take a while)... Complete! Configuring system... Generating public/private ed25519 key pair. Your identification has been saved in podman-machine-default Your public key has been saved in podman-machine-default.pub The key fingerprint is: SHA256:RGTGg2Q/LX7ijN+mzu8+BzcS3cEWP6Hir6pYllJtceA root@WINPC Machine init complete To start your machine run: podman machine start ``` Starting Machine After the machine init process completes, it can then be started and stopped as desired: ``` PS C:\Users\User> podman machine start Starting machine "podman-machine-default" This machine is currently configured in rootless mode. If your containers require root permissions (e.g. ports < 1024), or if you run into compatibility issues with non-podman clients, you can switch using the following command: podman machine set --rootful API forwarding listening on: npipe:////./pipe/docker_engine Docker API clients default to this address. You do not need to set DOCKER_HOST. Machine "podman-machine-default" started successfully ``` First Podman Command -- From this point on, podman commands operate similarly to how they would on Linux. For a quick working example with a small image, you can run the Linux date command on PowerShell. ``` PS C:\Users\User> podman run ubi8-micro date Thu May 5 21:56:42 UTC 2022 ``` Port Forwarding Port forwarding also works as expected; ports will be bound against localhost (127.0.0.1). Note: When running as rootless (the default), you must use a port greater than 1023. See the Rootful and Rootless section for more details. To launch httpd, you can run: ``` PS C:\Users\User> podman run --rm -d -p 8080:80 --name httpd docker.io/library/httpd f708641300564a6caf90c145e64cd852e76f77f6a41699478bb83a162dceada9 ``` A curl command against localhost on the PowerShell prompt will return a successful HTTP response: ``` PS C:\Users\User> curl http://localhost:8080/ -UseBasicParsing StatusCode : 200 StatusDescription : OK Content : <html><body><h1>It works!</h1></body></html> ``` As with Linux, to stop, run: `podman stop httpd` Using API Forwarding -- API forwarding allows Docker API tools and clients to use podman as if it was Docker. Provided there is no other service listening on the Docker API pipe; no special settings will be required. ``` PS C:\Users\User> .\docker.exe run -it fedora echo "Hello Podman!" Hello Podman! ``` Otherwise, after starting the machine, you will be notified of an environment variable you can set for tools to point to podman. Alternatively, you can shut down both the conflicting service and podman, then finally run `podman machine start` to restart, which should grab the Docker API address. ``` Another process was listening on the default Docker API pipe address. You can still connect Docker API clients by setting DOCKER HOST using the following PowerShell command in your terminal session: $Env:DOCKER_HOST = 'npipe:////./pipe/podman-machine-default' Or in a classic CMD prompt: set DOCKER_HOST=npipe:////./pipe/podman-machine-default Alternatively, terminate the other process and restart podman machine. Machine "podman-machine-default" started successfully PS C:\Users\User> $Env:DOCKER_HOST = 'npipe:////./pipe/podman-machine-default' PS C:\Users\User>.\docker.exe version --format '{{(index .Server.Components

Podman Engine ``` Rootful & Rootless On the embedded WSL Linux distro, podman can either be run under the root user (rootful) or a non-privileged user (rootless). For behavioral consistency with Podman on Linux, rootless is the default. Note: Rootful and Rootless containers are distinct and isolated from one another. Podman commands against one (e.g., podman ps) will not represent results/state for the other. While most containers run fine in a rootless setting, you may find a case where the container only functions with root privileges. If this is the case, you can switch the machine to rootful by stopping it and using the set command: ``` podman machine stop podman machine set --rootful ``` To restore rootless execution, set rootful to false: ``` podman machine stop podman machine set --rootful=false ``` Another case in which you may wish to use rootful execution is binding a port less than 1024. However, future versions of podman will likely drop this to a lower number to improve compatibility with defaults on system port services (such as MySQL) Volume Mounting New in Podman v4.1 is the ability to perform volume mounts from Windows paths into a Linux container. This supports several notation schemes, including: Windows Style Paths: `podman run --rm -v c:\Users\User\myfolder:/myfolder ubi8-micro ls /myfolder` Unixy Windows Paths: `podman run --rm -v /c/Users/User/myfolder:/myfolder ubi8-micro ls /myfolder` Linux paths local to the WSL filesystem: `podman run --rm -v /var/myfolder:/myfolder ubi-micro ls /myfolder` All of the above conventions work, whether running on a Windows prompt or the WSL Linux shell. Although when using Windows paths on Linux, appropriately quote or escape the Windows path portion of the argument. Listing Podman Machine(s) To list the available podman machine instances and their current resource usage, use the `podman machine ls` command: ``` PS C:\Users\User> podman machine ls NAME VM TYPE CREATED LAST UP CPUS MEMORY DISK SIZE podman-machine-default wsl 2 hours ago Currently running 4 331.1MB 768MB ``` Since WSL shares the same virtual machine and Linux kernel across multiple distributions, the CPU and Memory values represent the total resources shared across running systems. The opposite applies to the Disk value. It is independent and represents the amount of storage for each individual distribution. Accessing the Podman Linux Environment -- While using the podman.exe client on the Windows environment provides a seamless native experience supporting the usage of local desktop tools and APIs, there are a few scenarios in which you may wish to access the Linux environment: Updating to the latest stable packages on the embedded Fedora instance Using Linux development tools directly Using a workflow that relies on EXT4 filesystem performance or behavior semantics There are three mechanisms to access the embedded WSL distribution: SSH using `podman machine ssh` WSL command on the Windows PowerShell prompt Windows Terminal Integration SSH access provides a similar experience as Podman on

It immediately drops you into the appropriate user based on your machine's rootful/rootless configuration (root in the former, 'user' in the latter). The --username option can be used to override with a specific user. An example task using SSH is updating your Linux environment to pull down the latest OS bugfixes: `podman machine ssh sudo dnf upgrade -y` The `wsl` command provides direct access to the Linux system but enters the shell as root first. This is due to design limitations of WSL, where running systemd (Linux's system services) requires the usage of a privileged process namespace. Unless you have no other distributions of WSL installed, it's recommended to use the `-d` option with the name of your podman machine (podman-machine-default is the default) ``` PS C:\Users\User> wsl -d podman-machine-default ``` You will be automatically entered into a nested process namespace where systemd is running. If you need to access the parent namespace, hit `ctrl-d` or type exit. This also means to log out, you need to exit twice. ``` [root@WINPC /]# podman --version podman version 4.1.0 ``` To access commands as the non-privileged user (rootless podman), you must first type `su user`. Alternatively, you can prefix the `wsl` command to use the special `enterns`: ``` wsl -d podman-machine-default enterns su user [user@WINPC /]$ id uid=1000(user) gid=1000(user) groups=1000(user),10(wheel) ``` Likewise, running commands as root without entering a prompt should also be prefixed with `enterns`. `wsl -d podman-machine-default enterns systemctl status` Accessing the WSL instance as a specific user using `wsl -u` or using inline commands without `enterns` is not recommended since commands will execute against the incorrect namespace. Entering WSL as root is a 2-click operation. Simply click the drop-down tag, and pick 'podman-machine-default,' where you will be entered directly as root. As before, to switch to a non-privileged user for rootless podman commands, type `su user`. ``` [root@WINPC /]# su user [user@WINPC /]$ podman info --format '{{.Store.RunRoot}}' /run/user/1000/containers ``` Stopping a Podman Machine To stop a running podman machine, use the `podman machine stop` command: ``` PS C:\Users\User> podman machine stop Machine "podman-machine-default" stopped successfully ``` Removing a Podman Machine To remove a machine, use the `podman machine rm` command: ``` PS C:\Users\User> podman machine rm The following files will be deleted: C:\Users\User\.ssh\podman-machine-default C:\Users\User\.ssh\podman-machine-default.pub C:\Users\User\.local\share\containers\podman\machine\wsl\podman-machine-defaultfedora-35-x8664.tar C:\Users\User\.config\containers\podman\machine\wsl\podman-machine-default.json C:\Users\User\.local\share\containers\podman\machine\wsl\wsldist\podman-machine-default Are you sure you want to continue? [y/N] y ``` Troubleshooting Recovering from a failed auto-installation of WSL If auto-install fails and retrying is unsuccessful, you can attempt to reset your WSL system state and perform a manual WSL installation using the `wsl --install` command. To do so, perform the following steps: Launch PowerShell as administrator ``` Start-Process powershell -Verb RunAs ``` Disable WSL Features ``` dism.exe /online /disable-feature /featurename:Microsoft-Windows-Subsystem-Linux /norestart dism.exe /online /disable-feature /featurename:VirtualMachinePlatform /norestart ``` Reboot Run manual WSL install ``` wsl --install ``` Continue with podman machine init Install Certificate Authority ============================= Instructions for installing a CA certificate can be found .