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Building Glean from Source


Glean is written mainly in Haskell, and makes heavy use of Thrift for data communication and serialization, so these are the main dependencies that are needed for building Glean.

You will need​

  • Linux. The build is only tested on Linux so far; we hope to add support for other OSs in the future. We build on x86_64 and arm64v8.

  • GHC. To see which versions Glean is tested with, check the current ci.yml script.

  • Cabal/cabal-install version 3.6 or later (older versions won't work).

Additional per-distribution setup follows.


Install prerequisite packages. (many of these are dependencies of hsthrift; an up to date list can be found in the Dockerfile that we use for building the base image for CI).

sudo apt-get install \
g++ \
cmake \
make \
ninja-build \
bison flex \
git curl \
rsync m4 \
libzstd-dev \
libboost-all-dev \
libevent-dev \
libdouble-conversion-dev \
libgoogle-glog-dev \
libgflags-dev \
libiberty-dev \
liblz4-dev \
liblzma-dev \
libsnappy-dev \
zlib1g-dev \
binutils-dev \
libjemalloc-dev \
libssl-dev \
pkg-config \
libunwind-dev \
libsodium-dev \
libpcre3-dev \
libfftw3-dev \
libxxhash-dev \
libgtest-dev \
libfmt-dev \
clang-12 \
llvm-12 \


The package dependencies for Debian current are the same as above for Ubuntu.


Install prerequisite packages:

sudo dnf install \
g++ \
make \
cmake \
curl git \
rsync m4 \
ninja-build \
binutils \
bison flex \
libzstd-devel \
boost-devel \
libevent-devel \
double-conversion-devel \
glog-devel \
gflags-devel \
zlib-devel \
openssl-devel \
libunwind-devel \
libsodium-devel \
pcre-devel \
fftw-devel \
xxhash-devel \
snappy-devel \
lz4-devel \
gtest-devel \
fmt-devel \
xxhash \
clang \


Clone the repository:

git clone
cd Glean

Build hsthrift and dependencies​

Glean depends on hsthrift, folly, rocksdb and some other core libraries. We need to set paths to these that the Glean build can find the thrift compiler and associated libraries:

export LD_LIBRARY_PATH=$HOME/.hsthrift/lib:$HOME/.hsthrift/lib64:$LD_LIBRARY_PATH
export PKG_CONFIG_PATH=$HOME/.hsthrift/lib/pkgconfig:$HOME/.hsthrift/lib64/pkgconfig
export PATH=$PATH:$HOME/.hsthrift/bin

On Fedora/CentOS and possibly other non-Debian systems, you also need to set:

export LIBRARY_PATH=$HOME/.hsthrift/lib:$HOME/.hsthrift/lib64:$LIBRARY_PATH

These will build with either gcc or clang as the base C and C++ compilers. Clang is the best supported C++ compiler for this project.

Now we will clone hsthrift and build and install its dependencies:


Build Glean​

Now you can build all the Glean parts:


If everything worked, the tests should pass:

make test

At this point you can cabal install to install the executables into ~/.cabal/bin.

Tips for faster builds​

If you have 4 or more cores and at least 16G of ram, you can significantly speed up the build times by passing some flags to the build stages. On an 6 core machine with 16G of ram you might use, to save 50% or more of the build time.

./ --threads 6
make EXTRA_GHC_OPTS='-j4 +RTS -A128m -n2m -RTS'

Using clang++-12 and clang-12 as the C and C++ compilers can shave another 25% off the build time.