DRV_public

Unreal Linux container handoff

Objective

Run the latest packaged Linux release of UAVLab-SLU/DRV-Unreal in Docker, publish its Pixel Streaming player to the host, and display the DRV main menu when the simulation is idle.

This checkpoint changes the repository runtime to target a native Linux NVIDIA desktop. Native Linux validation is in progress.

Native Linux checkpoint (2026-08-26)

The host and container GPU prerequisites now pass on the Linux desktop:

• Host GPU: NVIDIA GeForce RTX 3090 Ti, driver 580.173.02, 24564 MiB.
• nvidia-modprobe was installed because the loaded kernel driver had not created /dev/nvidia*; host nvidia-smi now succeeds.
• The user was added to the docker group and the Docker CLI context was changed from desktop-linux to the native default engine. A new login may be required before new shells inherit the group.
• NVIDIA Container Toolkit is registered with the native engine.
• nvidia/cuda:12.8.0-base-ubuntu24.04 sees the same GPU and driver through --gpus all.
• The UE 5.5 signalling/TURN container is healthy and serves the player at http://localhost:8888.

Native Linux runtime validation now passes for release v2.1.0:

• Linux.zip was selected and staged under sim/release.
• The image is labeled v2.1.0; the GitHub token was used only by the host-side downloader and is not part of the sim build context.
• In-container vulkaninfo --summary identifies the physical RTX 3090 Ti and NVIDIA driver 580.173.02.
• The packaged Unreal application remained healthy for more than five minutes with zero container restarts.
• The signalling server registered DefaultStreamer and a browser player.
• The browser displayed the DRV main menu at 1920x1080 and 60 FPS using H.264, with zero dropped frames during validation.
• Hovering the browser mouse over City park map changed the Unreal menu highlight, confirming that the Pixel Streaming data channel carries input.

The runtime image needed both the GLVND EGL loader (libegl1) and an NVIDIA EGL vendor manifest. Without them, NVIDIA’s Vulkan ICD found libGLX_nvidia.so.0 but returned ERROR_INCOMPATIBLE_DRIVER while repeatedly failing to open libEGL.so.1.

AirSim RPC remains unverified at the idle main menu. Docker publishes host TCP 41451, but netstat inside the Unreal container shows no listener before a map is loaded. Do not count the Docker proxy accepting a host TCP connection as an RPC pass; validate an actual AirSim request after choosing a map.

Attempting that validation with Simple map exposed a packaged-release crash. Immediately after the AirSim vehicle-choice dialog closed with the quadrotor selection, Unreal logged r.CustomDepth = "3", caught signal 11, and exited with code 139. The container was not OOM-killed. The shipping build emitted no usable Unreal log or stack; its crash directory contained only CrashReportClient.ini. Restarting the same container restored the healthy main-menu streamer. Publish a new Linux package containing the prepared SM5 and no-hardware-ray-tracing settings, then repeat the map-load and AirSim RPC validation before marking criterion 8 complete.

Repository-side compatibility changes are prepared but not yet included in a published package: the sibling DRV-Unreal checkout explicitly targets Vulkan SM5 on Linux and disables hardware ray tracing in Config/DefaultEngine.ini.

Implemented workflow

• Host-side release downloaders query the GitHub latest release endpoint.
• The first Linux zip asset is selected, with Linux.zip preferred when more than one asset matches.
• Private release downloads support a GitHub token without putting the token in Docker layers.
• The extracted release is staged under ignored sim/release.
• The Docker image discovers DRV.sh, Blocks.sh, or SADE_drone_rep.sh.
• Unreal runs as a non-root user with native NVIDIA Vulkan and NVENC libraries injected by NVIDIA Container Toolkit.
• The entrypoint fails early when it detects Dozen, llvmpipe, CPU Vulkan, or no native NVIDIA device.
• Compose starts a UE 5.5 signalling server and local TURN relay.
• Unreal uses offscreen rendering and connects to ws://signalling:8888.
• AirSim settings can be mounted from AIRSIM_SETTINGS_DIR.
• DroneLume configuration is mounted from DRONELUME_CONFIG_DIR, defaulting to config/dronelume on the host. The launch script creates this directory and the container entrypoint links its InitDSL.json into the active packaged project’s Config directory before Unreal starts.

Primary files:

• download_sim_release.sh
• download_sim_release.ps1
• sim/Dockerfile
• sim/docker-entrypoint.sh
• docker-compose.yaml
• dev.sh
• dev.ps1
• sim/README.md

Windows investigation result

The image was built successfully on Docker Desktop with a local DRV 2.1.1 Linux package. The signalling player loaded at http://localhost:8888, but the Unreal streamer exited with code 139 before connecting.

Docker Desktop exposed /dev/dxg, not native /dev/nvidia* graphics devices. Mesa Dozen 26.1.7 could enumerate the RTX 4080 and reported approximately 15 GB of device-local memory. Full vulkaninfo completed successfully.

An Unreal debugger trace found the actual failure during Vulkan RHI startup:

D3D12: Removing Device.
LowLevelFatalError [VulkanMemory.cpp:926]
Out of Local Memory, Requested1024.00KB MemTypeIndex=0

The stack reached FScreenRectangleVertexBuffer::InitRHI and failed on its first 1 MB Vulkan allocation. The reported memory error was secondary to the Direct3D 12 device removal.

These launch variations produced the same failure:

• SM5 with ray tracing disabled
• reduced resolution and frame rate
• -FeatureLevelES31
• approximately 12.7 GB of free GPU memory

Mesa llvmpipe was also tested as a software Vulkan fallback. It enumerated as a conformant CPU Vulkan device, but the packaged application exited before initializing Unreal rendering.

Conclusion: packaging settings do not provide native Vulkan passthrough to a Linux container on Docker Desktop. Continue on native Linux.

Unreal packaging settings

The current Linux package selection is appropriate for the native Linux test:

• Vulkan Desktop SM5: enabled
• Vulkan Desktop SM6: disabled
• Vulkan Mobile ES3.1: disabled

The Unreal project configuration was found to enable hardware ray tracing while the Linux package targets SM5. Epic requires SM6 for Lumen hardware ray tracing. Before publishing the next Linux release, commit an explicit Linux RHI section and disable hardware ray tracing for the compatibility build:

[/Script/LinuxTargetPlatform.LinuxTargetSettings]
-TargetedRHIs=SF_VULKAN_SM5
+TargetedRHIs=SF_VULKAN_SM5

[/Script/Engine.RendererSettings]
r.RayTracing=False
r.Lumen.HardwareRayTracing=False
r.RayTracing.Shadows=False
r.RayTracing.Skylight=False
r.RayTracing.UseTextureLod=False
r.Vulkan.RayTracing=False

Do not enable SM6 for the first container validation. Do not use ES3.1 as the primary build. ES3.1 selects the mobile rendering path and would require a separate compatibility review for Cesium, AirSim camera materials, and the DRV menu.

Linux pickup procedure

1. Install and validate the host runtime

Install the current NVIDIA Linux driver, Docker Engine, Docker Compose v2, and NVIDIA Container Toolkit. Configure Docker according to NVIDIA’s installation guide, then restart Docker.

nvidia-smi
docker run --rm --gpus all nvidia/cuda:12.8.0-base-ubuntu24.04 nvidia-smi

Both commands must identify the same physical NVIDIA GPU.

2. Configure release access

./dev.sh token

The token is stored in ignored .env. For the private repository, authorize organization SSO and grant release read access.

3. Download and inspect the latest release

./download_sim_release.sh latest
cat sim/release/.release-tag
cat sim/release/.release-asset
find sim/release -maxdepth 3 -type f \
  \( -name DRV.sh -o -name Blocks.sh -o -name SADE_drone_rep.sh \)

4. Build

export DRV_RELEASE_TAG="$(<sim/release/.release-tag)"
docker compose build drv-unreal

5. Validate native Vulkan in the image

docker run --rm --gpus all \
  --entrypoint vulkaninfo \
  droneworld/drv-unreal:linux --summary

Required result:

• The device is the physical NVIDIA GPU.
• The driver is NVIDIA, not Dozen or llvmpipe.
• Vulkan initialization exits with status zero.

6. Start Pixel Streaming

./dev.sh simulator

In a second terminal:

docker compose ps
docker compose logs -f signalling drv-unreal

Open http://localhost:8888 on the Linux host.

Acceptance criteria

The workflow is complete only when:

1. The latest Linux release is selected without editing a version in the Dockerfile or Compose file.
2. The Unreal image builds without embedding the GitHub token.
3. The image uses the native NVIDIA Vulkan driver.
4. Unreal stays running for at least five minutes while idle.
5. The signalling server reports an Unreal streamer connection.
6. The host browser displays the DRV main menu.
7. Mouse input from the browser changes the menu selection.
8. AirSim RPC is reachable on host TCP port 41451.

If native Linux still fails

Capture these diagnostics before changing the image:

nvidia-smi
docker info
docker compose version
docker compose config
docker compose ps -a
docker compose logs --no-color signalling drv-unreal
docker run --rm --gpus all \
  --entrypoint vulkaninfo \
  droneworld/drv-unreal:linux --summary

Check the packaged Unreal log under its Saved/Logs directory. If the shipping build does not emit a log, retain -StdOut -FullStdOutLogOutput and run the binary under gdb with SYS_PTRACE and an unconfined seccomp profile.

Do not respond to Vulkan initialization errors by adding -nullrhi. That can allow simulation logic to run without rendering, but it cannot satisfy Pixel Streaming because there are no frames to encode.

References

• Epic Linux development requirements
• Epic Linux RHI settings
• Epic Pixel Streaming reference
• NVIDIA Container Toolkit installation

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