Linux build

• Requirements:
  • System specifics
  • Dependencies
• GitHub:
  • Create a GitHub account
  • Install git
  • Link GitHub and Unreal Engine
• Unreal Engine:
  • Download UE4.22
  • Build UE4.22
• CARLA build:
  • Clone repository
  • Get assets
  • Set the environment variable
  • make CARLA

The build process can be quite long and tedious. This documentation tries to make things clear and provides for a F.A.Q. with solutions for the most common starting issues. However, the CARLA forum is open for anybody to post unexpected issues, doubts or suggestions. There is a specific section for installation issues on Linux. Feel free to login and become part of the community.

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Requirements

System specifics

• Ubuntu 16.04 or later: Currently migrating to Ubuntu 18, but there is support up to Ubuntu 16.04.
• 30GB disk space: Installing all the software needed and CARLA itself will require quite a lot of space, especially Unreal Engine. Make sure to have around 30/50GB of free disk space.
• An adequate GPU: CARLA aims for realistic simulations, so the server needs at least a 4GB GPU. A dedicated GPU is highly recommended for machine learning.
• Two TCP ports and good internet connection: 2000 and 2001 by default. Be sure neither firewall nor any other application are blocking these.

Dependencies

CARLA needs many dependencies to run. Some of them are built automatically during this process, such as Boost.Python. Others are binaries that should be installed before starting the build (cmake, clang, different versions of Python and much more). In order to do so, run the commands below in a terminal window.

sudo apt-get update &&
sudo apt-get install wget software-properties-common &&
sudo add-apt-repository ppa:ubuntu-toolchain-r/test &&
wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add - &&
sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-7 main" &&
sudo apt-get update

Ubuntu 18.04:

sudo apt-get install build-essential clang-7 lld-7 g++-7 cmake ninja-build libvulkan1 python python-pip python-dev python3-dev python3-pip libpng-dev libtiff5-dev libjpeg-dev tzdata sed curl unzip autoconf libtool rsync libxml2-dev &&
pip2 install --user setuptools &&
pip3 install --user setuptools 

Previous Ubuntu versions:

sudo apt-get install build-essential clang-7 lld-7 g++-7 cmake ninja-build libvulkan1 python python-pip python-dev python3-dev python3-pip libpng16-dev libtiff5-dev libjpeg-dev tzdata sed curl unzip autoconf libtool rsync libxml2-dev &&
pip2 install --user setuptools &&
pip3 install --user setuptools 

Finally, to avoid compatibility issues between Unreal Engine and the CARLA dependencies, it is recommended to use the same compiler version and C++ runtime library to compile everything. The CARLA team uses clang-7 and LLVM's libc++. Change your default clang version to compile Unreal Engine and the CARLA dependencies.

sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/lib/llvm-7/bin/clang++ 170 &&
sudo update-alternatives --install /usr/bin/clang clang /usr/lib/llvm-7/bin/clang 170

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GitHub

First of all, a GitHub account will be needed, as CARLA content is organized in different repositories in there. Also, git will be used in this build guide when facilitating commands to be run in terminal.

In order to access the Unreal Engine repositories, which are set to private, create an Unreal Engine account and connect it to a GitHub account. To do so, there is a section in Unreal Engine's profile settings under the name of Connected accounts. Here is a brief explanation just in case.

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Unreal Engine

The current version of CARLA runs on Unreal Engine 4.22 only, so the following steps will be downloading this version and building it. The path is irrelevant, but for the sake of this tutorial, installation will be done under ~/UnrealEngine_4.22. If the path chosen differs, remember to change it accordingly when running the commands on terminal.
The process described below can be found in this complete guide on how to build Unreal Engine on Linux. It can be consulted if preferred, but remember though that CARLA will need the 4.22 release, not the latest.

Clone the content for Unreal Engine 4.22 in a local computer:

git clone --depth=1 -b 4.22 https://github.com/EpicGames/UnrealEngine.git ~/UnrealEngine_4.22

Get into said folder. Remember, this is the path where you cloned UE4.22:

cd ~/UnrealEngine_4.22

Run the commands necessary to make the build.

./Setup.sh && ./GenerateProjectFiles.sh && make

Unreal Engine should be installed in the system. To try running it go to Engine/Binaries/Linux folder and run the UE4Editor.sh:

cd ~/UnrealEngine_4.22/Engine/Binaries/Linux && ./UE4Editor

If anything goes wrong, it is related with Unreal Engine and there is not much CARLA can do about it. However, checking the guide mentioned above or visiting the build documentation provided by Unreal Engine could be helpful.

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CARLA build

The system should be ready to start building CARLA. Just for clarity, a brief summary so far:

• Minimum technical requirements to run CARLA are suitable.
• Dependencies have been properly installed.
• GitHub account is ready.
• Unreal Engine 4.22 runs smooth.

Clone repository

The project can be found in GitHub. Either download and extract it or clone it on the local computer using the following command line:

git clone https://github.com/carla-simulator/carla

Now the latest content for the project, known as master branch in the repository, has been copied in local.

Get assets

Only the assets package, the visual content, is yet to be donwloaded. These are stored separately to make the repository a bit lighter. CARLA cannot be built without the assets, so there is a script that downloads and extracts the latest content version (this package is >3GB, it might take some time depending on internet connection).
Get into the root carla folder. The path should correspond with the repository just cloned:

cd ~/carla

Run the script to get the assets:

./Update.sh

Set the environment variable

For CARLA to find the Unreal Engine 4.22 installation folder, an environment variable needs to be set.

export UE4_ROOT=~/UnrealEngine_4.22

This variable should be added to ~/.bashrc or ~/.profile to set it persistently session-wide. Otherwise, it will only be accessible for current shell.

make CARLA

The last step is to finally build CARLA. There are different make commands to build the different modules. All of them run in the root CARLA folder:

• launch will compile the server simulator and launch it in Unreal Engine. Press Play to start the spectator view and close the editor window to exit. Camera can be moved with WASD keys and rotated by clicking the scene while moving the mouse around:

make launch

The project may ask to build other instances such as UE4Editor-Carla.dll the first time. Agree in order to open the project. Also, during the first launch Unreal Editor may show warnings regarding shaders and mesh distance fields. These take some time to be loaded and the city will not show properly until then.

• PythonAPI will compile the API client, necessary to grant control over the simulation. It is only needed the first time (remember to run it again when the CARLA code is updated). After building it, scripts can run. The following example will spawn some life into the city:

make PythonAPI && cd PythonAPI/examples && python3 spawn_npc.py

Now everything is ready to go and CARLA has been successfully built. Here is a brief summary of the most useful make commands available:

Command	Description
make help	Prints all available commands.
make launch	Launches CARLA Editor.
make PythonAPI	Builds the CARLA client.
make package	Builds CARLA and creates a packaged version for distribution.
make clean	Deletes all the binaries and temporals generated by the build system.
make rebuild	make clean and make launch both in one command.

Keep reading this section to learn more about how to update CARLA, the build itself and some advanced configuration options. Otherwise, visit the First steps section to learn about CARLA: