Add Linux support for LocalMultiplayerAgent (containers and processes) by Copilot · Pull Request #210 · PlayFab/MpsAgent

Copilot · 2026-04-08T08:18:39Z

LocalMultiplayerAgent supported MacOS (containers only) and Windows (both modes), but Linux was limited to process mode only with container mode explicitly rejected. This PR enables both Linux containers and Linux processes on native Linux. Linux support is marked as beta, matching the MacOS pattern.

Core changes

Program.cs: Auto-set GameServerEnvironment.Linux on Linux OS, matching the MacOS pattern
MultiplayerSettingsValidator.cs: Remove the RunContainer=true rejection on Linux; narrow the Linux+!RunContainer guard to only reject on non-Linux hosts (Windows LCOW still requires containers)
MultiplayerServerManager.cs: Add Linux to the docker image pull path alongside MacOS/Windows

// Before: Linux was explicitly blocked
if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux) && _settings.RunContainer)
    return false;

// After: only reject Linux process mode on non-Linux hosts
if (Globals.GameServerEnvironment == GameServerEnvironment.Linux && !_settings.RunContainer
    && !RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
    return false;

New files

setup_linux.sh — Docker network setup script (mirrors setup_macos.sh)
Samples/MultiplayerSettingsLinuxContainersOnLinuxSample.json / Samples/MultiplayerSettingsLinuxProcessOnLinuxSample.json — Sample configs for both modes
docs/linux.md — Documentation covering container mode, process mode, building from source, and troubleshooting

Project reorganization

Moved OS-related markdown files (linux.md, macos.md, lcow.md) from the repository root into a docs/ folder
Moved all MultiplayerSettings sample JSON files into a LocalMultiplayerAgent/Samples/ folder
Updated all references in README.md, LocalMultiplayerAgent/readme.md, LocalMultiplayerAgent.csproj, and docs to point to the new paths

Documentation

Marked Linux support as (beta) in both README.md and LocalMultiplayerAgent/readme.md, consistent with the MacOS beta labeling
Added Linux to the supported platforms list in LocalMultiplayerAgent/readme.md

Tests

Replaced LinuxOsRejectsContainerMode with LinuxOsAcceptsContainerMode + LinuxOsAcceptsProcessMode
Removed Assert.Inconclusive / skip guards on container-mode tests that were gated on !Linux — these now run on Linux
LinuxGameServerEnvironmentWithoutContainerFails narrowed to skip on native Linux where process mode is valid

- Remove Linux container mode restriction in MultiplayerSettingsValidator - Set GameServerEnvironment to Linux on native Linux OS in Program.cs - Allow Linux process mode on native Linux in validator - Force docker pull on Linux for container mode - Fix hardcoded Windows path separator in ProcessRunner - Create setup_linux.sh setup script - Create sample configs for Linux containers and processes - Create linux.md documentation - Update README.md with Linux platform support - Update tests to reflect Linux now supports both modes Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/ef46bb0d-1884-40a4-a3be-8f778e0967be Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

dgkanatsios · 2026-04-08T08:20:29Z

VmAgent.Core/Interfaces/ProcessRunner.cs

            // (and were based off of the parameters for containers).
            string executablePath = sessionHostsStartInfo.AssetDetails[0].MountPath?.Length > 0
-                ? parts[0].Replace(sessionHostsStartInfo.AssetDetails[0].MountPath, $"{localPathForAsset0}\\")
+                ? parts[0].Replace(sessionHostsStartInfo.AssetDetails[0].MountPath, $"{localPathForAsset0}{Path.DirectorySeparatorChar}")


@copilot how come was this line working on MacOS?

This line was never reached on MacOS — MacOS only supports container mode (RunContainer=true is enforced by the validator at MultiplayerSettingsValidator.cs:115-122), so ProcessRunner is never instantiated or used there. The \\ was only ever executed on Windows. With this PR enabling process mode on Linux, the hardcoded \\ would produce incorrect paths on Linux, hence the fix to Path.DirectorySeparatorChar.

@copilot yeah but on the production PlayFab Multiplayer Servers page, we have this code running on Linux processes and containers,

You're right — my earlier answer was too narrow. VmAgent.Core is shared with production MPS, so this \\ was a pre-existing latent bug on Linux there as well, not just a LocalMultiplayerAgent issue. It would produce incorrect paths any time the MountPath?.Length > 0 back-compat branch is taken on a Linux host. The fix to Path.DirectorySeparatorChar corrects it for all platforms (production MPS and LocalMultiplayerAgent alike).

@copilot but there is no bug on the production MPS service, Linux processes and containers work just fine.

You're right — this branch is never reached on Linux. In process mode, MountPath is set to null (see MultiplayerSettings.cs:66: MountPath = RunContainer ? x.MountPath : null), so the MountPath?.Length > 0 condition is always false and the \\ is never executed. Reverted in 3a22157.

You're right — this branch is never reached on Linux. In process mode, MountPath is set to null (MultiplayerSettings.cs:66: MountPath = RunContainer ? x.MountPath : null), so the MountPath?.Length > 0 condition is always false and the \\ is never executed. In container mode, ProcessRunner isn't used at all. Reverted in 3a22157.

dgkanatsios · 2026-04-08T08:20:58Z

docs/linux.md

@@ -0,0 +1,161 @@
+# Linux Support


@copilot can we move these OS related md files into their own folder? Make sure to update all references

Moved linux.md, macos.md, and lcow.md into a docs/ folder and updated all references in README.md and LocalMultiplayerAgent/readme.md (5e28122).

Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/d05f2051-b8cb-49dc-be6d-723ac8c87075 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

… taken on Linux Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/1c40afcc-5189-4bdd-86d5-6c86de49f0d6 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

dgkanatsios · 2026-04-08T08:42:40Z

LocalMultiplayerAgent/MultiplayerSettingsLinuxContainersOnLinuxSample.json

@@ -0,0 +1,40 @@
+{


@copilot let's remove all this MultiplayerSettings sample files on a separate folder. Make sure to update all references

Moved all 4 sample JSON files into LocalMultiplayerAgent/Samples/ and updated references in the .csproj, docs, and readme (2cc8e4c).

… all references Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/61f546a2-ffa9-4df1-a391-95ea4fb3bf80 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

dgkanatsios · 2026-04-08T08:59:01Z

@copilot make sure to state in the README that this running on Linux is a beta (like we did for MacOS)

Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/78085e91-d9bf-4b9a-9085-b72d3f40747c Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

Copilot · 2026-04-08T09:00:25Z

@copilot make sure to state in the README that this running on Linux is a beta (like we did for MacOS)

Added "(beta)" to Linux in both README.md and LocalMultiplayerAgent/readme.md, matching the MacOS pattern (c9b6044).

Copilot AI assigned Copilot and dgkanatsios Apr 8, 2026

Copilot created this pull request from a session on behalf of dgkanatsios April 8, 2026 08:18 View session

dgkanatsios reviewed Apr 8, 2026

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Copilot started work on behalf of dgkanatsios April 8, 2026 08:20 View session

dgkanatsios reviewed Apr 8, 2026

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Copilot AI requested a review from dgkanatsios April 8, 2026 08:23

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Copilot started work on behalf of dgkanatsios April 8, 2026 08:24 View session

Move OS-related md files into docs/ folder and update all references

5e28122

Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/d05f2051-b8cb-49dc-be6d-723ac8c87075 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

Copilot finished work on behalf of dgkanatsios April 8, 2026 08:29

Copilot started work on behalf of dgkanatsios April 8, 2026 08:29 View session

Copilot finished work on behalf of dgkanatsios April 8, 2026 08:33

Copilot started work on behalf of dgkanatsios April 8, 2026 08:38 View session

Revert ProcessRunner.cs change: MountPath back-compat branch is never…

3a22157

… taken on Linux Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/1c40afcc-5189-4bdd-86d5-6c86de49f0d6 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

dgkanatsios reviewed Apr 8, 2026

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Copilot AI requested a review from dgkanatsios April 8, 2026 08:46

Copilot finished work on behalf of dgkanatsios April 8, 2026 08:47

Copilot started work on behalf of dgkanatsios April 8, 2026 08:47 View session

Move MultiplayerSettings sample files into Samples/ folder and update…

2cc8e4c

… all references Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/61f546a2-ffa9-4df1-a391-95ea4fb3bf80 Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

Copilot finished work on behalf of dgkanatsios April 8, 2026 08:54

Copilot started work on behalf of dgkanatsios April 8, 2026 08:59 View session

Mark Linux support as beta in README and LocalMultiplayerAgent readme

c9b6044

Agent-Logs-Url: https://github.com/PlayFab/MpsAgent/sessions/78085e91-d9bf-4b9a-9085-b72d3f40747c Co-authored-by: dgkanatsios <8256138+dgkanatsios@users.noreply.github.com>

Copilot finished work on behalf of dgkanatsios April 8, 2026 09:01

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