Automatically fills a Lancache with games from Steam, so that subsequent downloads for the same content will be served from the Lancache, improving speeds and reducing load on your internet connection.
- Selecting which apps to prefill can be done through an interactive menu.
- Supports login with Steam Guard, and Steam Guard Mobile Authenticator
- No installation required! A completely self-contained, portable application.
- Multi-platform support (Windows, Linux, MacOS, Arm64, Docker, Unraid)
- High-performance! Downloads are significantly faster than using Steam. Downloads can scale all the way up to 100gbit/s!
- Game downloads write no data to disk, so there is no need to have enough free space available. This also means no unnecessary wear-and-tear to SSDs!
- Completely implemented from scratch, has no dependency on
SteamCMD! - No Steam API key required!
SteamPrefill is flexible and portable, and supports multiple platforms and configurations. It can be run on directly on the Lancache server itself, or on your gaming machine as an alternative Steam client. You should decide which one works better for your use case.
Detailed setup guides are available for the following platforms:
Warning This guide was written with Linux in mind. If you are running SteamPrefill on Windows you will need to substitute
./SteamPrefillwith.\SteamPrefill.exeinstead.
Prior to prefilling for the first time, you will have to decide which apps should be prefilled. This will be done using an interactive menu, for selecting what to prefill from all of your currently owned apps. To display the interactive menu, run the following command
./SteamPrefill select-appsOnce logged into Steam, all of your currently owned apps will be displayed for selection. Navigating using the arrow keys, select any apps that you are interested in prefilling with space. Once you are satisfied with your selections, save them with enter.
These selections will be saved permanently, and can be freely updated at any time by simply rerunning select-apps again at any time.
Now that a prefill app list has been created, we can now move onto our initial prefill run by using
./SteamPrefill prefillThe prefill command will automatically pickup the prefill app list, and begin downloading each app. During the initial run, it is likely that the Lancache is empty, so download speeds should be expected to be around your internet line speed (in the below example, a 300mbit/s connection was used). Once the prefill has completed, the Lancache should be fully ready to serve clients cached data.
Updating any previously prefilled apps can be done by simply re-running the prefill command, which will use same prefill app list as before.
SteamPrefill keeps track of which version of each app was previously prefilled, and will only re-download if there is a newer version of the app available. Any apps that are currently up to date, will simply be skipped. The number of apps already up to date will be displayed in the end of run summary table:
However, if there is a newer version of an app that is available, then SteamPrefill will re-download the app. Due to how Lancache works, this subsequent run should complete much faster than the initial prefill (example below used a 10gbit connection). Any data that was previously downloaded, will be retrieved from the Lancache, while any new data from the update will be retrieved from the internet. Any apps that have been updated will be counted towards the "Updated" column in the end of run summary.
SteamPrefill, like Steam, will never save your password. Your password will only be temporarily used once during the initial login, and won't be save to disk anywhere. Upon login SteamPrefill will receive an "access token" that will be used on future logins, no password required. Since SteamPrefill is open source, you can validate that this is indeed how your password is being used in the source code.
For extra account security, it is good practice to enable 2 Factor Authentication (2FA) for your account using Steam Guard Mobile Authenticator. The authenticator generates a code that you need to enter every time that you log on to your Steam account. The code changes every 30 seconds, can be used only once, and is unguessable. To get setup, see the guide How to set up a Steam Guard Mobile Authenticator
You certainly can! All you need to do is download SteamPrefill onto the server, and run it as you regularly would!
If everything works as expected, you should see a message saying it found the server at 127.0.0.1
Running from a Docker container on the Lancache server is also supported! You should instead see a message saying the server was found at 172.17.0.1
Running on the Lancache server itself can give you some advantages over running SteamPrefill on a client machine, primarily the speed at which you can prefill apps.
Since there is no network transfer happening, the prefill should only be limited by disk I/O and CPU throughput.
For example, using a SK hynix Gold P31 2TB NVME and running prefill --force on previously cached game yields the following performance
Yes it can! Scheduled jobs can be easily setup on Linux using systemd services, and can be flexibly configured to run on any schedule that you desire.
See Configuring a Nightly Job for a guide on how to get setup with a schedule.
Depending on the terminal that you are using, and what colors your system supports, you may see output similar to the following:
[6:20:46 PM] Starting �[38;5;80mCounter-Strike: Global Offensive�[0m
[6:20:46 PM] Downloading �[38;5;170m12.91 GiB�[0m
One of the reasons you may be seeing this is that your terminal is misreporting what capabilities it supports, thus receiving output that it can't handle.
To remove these characters from the log, simply use the flag --no-ansi which will remove all unsupported characters from the application's output.
Unfortunately it is not possible to fill a Lancache using games that have been installed with Steam. The installed games are in a different format than what Lancache caches, as they are decrypted and unzipped from the raw request. The decryption/unzip process is not reversible. Thus, the only way to get games properly cached is to redownload them using either SteamPrefill or Steam
You may want to limit the download speed of SteamPrefill to prevent it from potentially saturating your entire connection, causing other devices to suffer from massive latency and poor speeds. This issue is known as bufferbloat, and more detailed information on the issue can be found here: What is bufferbloat?
SteamPrefill does not currently contain any functionality to limit its own download speed, and due to the way that downloads are implemented will likely never be able to throttle its own download speed. Additionally, even if SteamPrefill was able to throttle itself, the same issue would persist with downloads through Steam.
One method to limit bandwidth would be to configure Quality of Service (QOS) on your router, limiting bandwidth to the Lancache server, or by prioritizing other network traffic. A general overview of QOS can be found here : Beginners guide to QOS
For more brand specific guides (non-exhaustive), see :
You can pause your downloads at any time by simply pressing CTRL + C, which will immediately terminate the application. This won't hurt anything at all, and SteamPrefill will pickup where it left off during the next prefill run.
While it would certainly be helpful (and cheaper!) to prefill apps that you don't own, it is unfortunately not possible. In order to download from the Steam network, Steam requires you to authenticate with your username and password. Steam keeps track of which apps you own, which is how SteamPrefill displays the list of available apps in select-apps. When SteamPrefill attempts to download any app (owned or unowned) the Steam network will validate that you do indeed own that app. If you do not own it, then the Steam network will simply refuse to let you download it.
Note Detailed command documentation has been moved to the wiki : Detailed Command Usage
SteamPrefill will automatically check for updates, and notify you when an update is available :
- Windows
- Run the
.\update.ps1script in the executable directory
- Run the
- Linux
- First time only : Grant executable permissions to the update script with
chmod +x ./update.sh - Run the
./update.shscript in the executable directory
- First time only : Grant executable permissions to the update script with
- Docker
docker pull tpill90/steam-lancache-prefill:latest
- Download the latest version for your OS from the Releases page.
- Unzip to the directory where SteamPrefill is currently installed, overwriting the previous executable.
- Thats it! You're all up to date!
If you are running into any issues, feel free to open up a Github issue on this repository.
You can also find us at the LanCache.NET Discord, in the #steam-prefill channel.
- Interested in compiling the project from source? See Development Setup Guide
- @dlrudie for all your help with debugging and testing!
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