Building

Prerequisites

This section describes the steps to build ngen from source.

🔶 Important: ngen does not support building on Windows or with MSVC.

Required Dependencies

ngen requires the following dependencies for core execution:

• C/C++ Compiler supporting C++14
  • gcc (≥8.0.0)
  • clang (≥3.4)
  • IntelLLVM (icx/icpx)
• CMake (≥3.17)
• UDUNITS
• Boost (≥1.72.0)

Note

Only Boost headers are required. As a result, we will vendor in a copy of 1.72.0 after cloning the ngen repository. Package managers typically support installing a system-wide version of Boost, and that will be okay as long as the installed version is at least 1.72.0.

Ubuntu

apt-get install \
	build-essential \ # for gcc
    cmake           \ # for cmake
    libudunits2-dev   # for udunits2

RHEL7

yum install \
	devtoolset-8 \ # for gcc 8
	cmake \        # for cmake
	udunits2-devel # for udunits2

# scl enable devtoolset-8 bash # enable to use gcc

RHEL8

dnf install \
	gcc-toolset-8 \
	cmake \
	udunits2-devel

# scl enable gcc-toolset-8 bash # enable to use gcc

macOS

brew install \
	gcc \
	cmake \
	udunits

Optional Dependencies

The following optional dependencies allow for additional features when building ngen:

• Python (≥3.9)
  • Enables embedded Python support and routing support.
• SQLite3
  • Enables GeoPackage reading support.
• NetCDF
  • Enables NetCDF I/O support.
• OpenMPI / MPI Implementation
  • Enables parallel orchestration.

Building

Clone the ngen repo:

git clone https://github.com/NOAA-OWP/ngen.git
cd ngen

Update git submodules

git submodule update --init --recursive

Note

If you do not have a system Boost installation, then you can vendor 1.72.0:

wget https://boostorg.jfrog.io/artifactory/main/release/1.72.0/source/boost_1_72_0.tar.gz
tar -xvf boost_1_72_0.tar.gz

This will download Boost 1.72.0 into your current directory, then untar it as boost_1_72_0/. To use this directory when building ngen, add -DBOOST_ROOT=boost_1_72_0/ to the command-line options below. If you need to force this vendored copy to be used, then add -DBoost_NO_BOOST_CMAKE:BOOL=ON as well.

Create an out-of-source build with any required options set:

cmake \
	-DNGEN_WITH_MPI:BOOL=OFF         \ # Enable MPI
	-DNGEN_WITH_NETCDF:BOOL=ON       \ # Enable NetCDF
	-DNGEN_WITH_SQLITE:BOOL=OFF      \ # Enable SQLite
	-DNGEN_WITH_UDUNITS:BOOL=ON      \ # Enable UDUNITS
	-DNGEN_WITH_BMI_FORTRAN:BOOL=OFF \ # Enable Fortran
	-DNGEN_WITH_BMI_C:BOOL=ON        \ # Enable C
	-DNGEN_WITH_PYTHON:BOOL=ON       \ # Enable Python
	-DNGEN_WITH_ROUTING:BOOL=ON      \ # Enable t-route
	-DNGEN_WITH_TESTS:BOOL=OFF       \ # Build unit tests
	-DNGEN_QUIET:BOOL=OFF            \ # Suppress output
	-B cmake_build                   \ # Build directory
	-S .

Build the ngen executable:

cmake \
	--build cmake_build \ # Build directory
	-t ngen             \ # Target
	--                  \ 
	-j $(nproc)

Now, you can run ./ngen to see the usage text.