Setting up Robust.Cdn

Robust.Cdn is the dedicated server for providing manifest-based delta updates without server ACZ.

The TL;DR of how Robust.Cdn operates is that it ingests directories of client zip files whenever you push a new build, then generates manifests and exposes the manifest and endpoint to do delta downloads. The games files are cached in an SQLite DB similar to how the launcher stores it.

Prerequisites

You will need the ASP.NET Core 6 runtime installed.

Building

Clone the code, then compile it with dotnet publish -c Release -r linux-x64 --no-self-contained The files will be dropped in Robust.Cdn/bin/Release/net6.0/linux-x64/publish. Robust.Cdn is the executable to run, but obviously copy everything else too.

Server File Layout

You’re going to want to put the server files somewhere on your uhhh, server. We put them at /opt/robust_cdn, with the following directory structure:

/opt/robust_cdn/
├── appsettings.json
├── run.sh
├── bin
│   ├── Robust.Cdn
│   ├── Robust.Cdn.dll
		.

The run.sh looks like this by the way, yes it’s just that simple:

#!/bin/sh

exec bin/Robust.Cdn

The actual program files go in a subfolder, and we run it from the parent directory so you don’t bulldoze the config files with updates or something.

Configuration

The configuration file is appsettings.json in the current working directory you run the server program from. You need to change at least two configuration settings: the disk path of your game versions, and the update token to trigger updates. Maybe port too.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  // change port for the server to bind to here
  "Urls": "http://localhost:27690/",
  "Cdn": {
    // See https://github.com/space-wizards/Robust.Cdn/blob/master/Robust.Cdn/CdnOptions.cs for all options.
    // Yes you can have comments in here by the way.
    // Change this update token so people don't uh... spam update checks on your server.
    "UpdateToken": "change this",
    // Increase this to reduce bandwidth usage for large downloads. Higher numbers need more CPU.
    "StreamCompressLevel": 5,
    // The file path of the SQLite database used by the server.
    // You can change this to put it on another drive or something if you want.
    // Personally we put it on our server's HDD instead of the SSD, but that's up to you.
    "DatabaseFileName": "content.db",
    // The directory path containing the versioned client builds to load and serve. 
    // See below for explanation
    "VersionDiskPath": "/var/lib/wizards-builds/builds"
  }
}

Version disk

Robust.Cdn needs a directory containing builds to load, with the following layout:

/var/lib/wizards-builds/builds
├── 02030cfa0ed6511ec5527c5b7d1f8bcd46fe1435
│   ├── SS14.Client.zip
│   ├── SS14.Server_linux-arm64.zip
│   ├── SS14.Server_linux-x64.zip
│   ├── SS14.Server_osx-x64.zip
│   └── SS14.Server_win-x64.zip
├── 021d39be2876f991c5fd6e663760a921d29ac694
│   ├── SS14.Client.zip
│   ├── SS14.Server_linux-arm64.zip

It will look for SS14.Client.zip (configurable) in each subdirectory to the directory to specify. The subdirectory’s name is the “version” of content. (Note: these are hashes because we use the Git commit hash as version “number”. They are not tied to manifest or zip hashes in any way, and can be any string, really).

Automatic detection of new versions

You can use something like the following to trigger Robust.Cdn to scan for new versions in the version directory:

curl -X POST -d "" -H 'Authorization: Bearer <token from the config file, change this>' "http://localhost:27690/control/update"

API endpoints / build metadata

Robust.Cdn exposes the /version/{version}/manifest and /version/{version}/download endpoints that do the actual updating. These need to be specified in the build.json in your server files, which you probably want to just specify by modifying gen_build_info.py or something. The new metadata required is as follows:

// (example from Wizard's Den servers)
{
    "download": "https://cdn.centcomm.spacestation14.com/builds/wizards/builds/{FORK_VERSION}/SS14.Client.zip",
    "hash": "49a7f54eb7e848c0a438bcfd3a198454d862e7d58d3e11c7ce60e281ddbd205d",
    "version": "e769ad27256300cfbbf10d641930d43990bff309",
    "fork_id": "wizards",
    "engine_version": "0.12.1.0",
    // These ones are new
    "manifest_url": "https://cdn.centcomm.spacestation14.com/cdn/version/{FORK_VERSION}/manifest",
    "manifest_download_url": "https://cdn.centcomm.spacestation14.com/cdn/version/{FORK_VERSION}/download",
    "manifest_hash": "8B175E9D944F54C1444E93E19C39EB255353392B316118B660F21DF68D56DC2D"
}

Info

Note the ability to specify {FORK_VERSION} in the build.json file. This gets replaced by version from the JSON at runtime. This way the URL does not need to duplicate the version string, and the URL template can be changed via CVar while the entry in build.json stays the same. Other possible keys are {FORK_ID}, {MANIFEST_HASH} and {ZIP_HASH}.

  • manifest_url is the /manifest endpoint on Robust.Cdn. The version must be included in the URL for Robust.Cdn to work.
  • manifest_download_url is the /download endpoint. Same rules as above.
  • manifest_hash must be the manifest hash. This hash is automatically generated by gen_build_info.py now and should just work.

Systemd Unit

We personally use systemd to start the server:

[Unit]
Description=Robust.Cdn

[Service]
Type=notify
WorkingDirectory=/opt/robust_cdn/
ExecStart=/opt/robust_cdn/run.sh
User=robust_cdn
Group=robust_cdn

[Install]
WantedBy=multi-user.target

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