Building Packages

A BinaryBuilder.jl build script (what is often referred to as a build_tarballs.jl file) looks something like this:

using BinaryBuilder

name = "libfoo"
version = v"1.0.1"
sources = [
    ArchiveSource("<url to source tarball>", "sha256 hash"),

script = raw"""
cd ${WORKSPACE}/srcdir/libfoo-*
make -j${nproc}
make install

platforms = supported_platforms()

products = [
    LibraryProduct("libfoo", :libfoo),
    ExecutableProduct("fooifier", :fooifier),

dependencies = [

build_tarballs(ARGS, name, version, sources, script, platforms, products, dependencies)

The build_tarballs function takes in the variables defined above and runs the builds, placing output tarballs into the ./products directory, and optionally generating and publishing the JLL package. Let's see in more details what are the ingredients of the builder.


This is the name that will be used in the tarballs and for the JLL package. It should be the name of the upstream package, not for example that of a specific library or executable provided by it, even though they may coincide. The case of the name should match that of the upstream package. Note that the name should be a valid Julia identifier, so it has meet some requirements, among which:

  • it cannot start with a number,
  • it cannot have spaces, dashes, or dots in the name. You can use underscores to replace them.

If you are unsure, you can use Base.isidentifer to check whehter the name is acceptable:

julia> Base.isidentifier("valid_package_name")

julia> Base.isidentifier("100-invalid")

Note that _jll will be automatically appended to the name of the generated JLL package.

Version number

This is the version number used in tarballs and should coincide with the version of the upstream package. However, note that this should only contain major, minor and patch numbers, so

julia> v"1.2.3"

is acceptable, but

julia> v"1.2.3-alpha"

julia> v"1.2.3+3"

or a version including more than three levels (e.g., are not. Truncate the version to the patch number if necessary.

The generated JLL package will automatically add a build number, increasing it for each rebuild of the same package version.


The sources are what will be compiled with the build script. They will be placed under ${WORKSPACE}/srcdir inside the build environment. Sources can be of the following types:

  • ArchiveSource: a compressed archive (e.g., tar.gz, tar.bz2, tar.xz, zip) that will be downloaded and automatically uncompressed;
  • GitSource: a git repository that will be automatically cloned. The specified revision will be checked out;
  • FileSource: a generic file that will be downloaded from the Internet, without special treatment;
  • DirectorySource: a local directory whose content will be copied in ${WORKSPACE}/srcdir. This usually contains local patches used to non-interactively edit files in the source code of the package you want to build.

Example of packages with multiple sources of different types:

Sources are not to be confused with the binary dependencies.


Each builder should build a single package: don't use multiple sources to bundle multiple packages into a single recipe. Instead, build each package separately, and use them as binary dependencies as appropriate. This will increase reusability of packages.

Build script

The script is a bash script executed within the build environment, which is a x86_64 Linux environment using the Musl C library, based on Alpine Linux (triplet: x86_64-linux-musl). The section Build Tips provides more details about what you can usually do inside the build script.


The builder should also specify the list of platforms for which you want to build the package. At the time of writing, we support Linux (x86_64, i686, armv7l, aarch64, ppc64le), Windows (x86_64, i686), macOS (x86_64) and FreeBSD (x86_64). When possible, we try to build for all supported platforms, in which case you can set

platforms = supported_platforms()

You can get the list of the supported platforms and their associated triplets by using the functions supported_platforms and triplet:

julia> using BinaryBuilder

julia> supported_platforms()
13-element Vector{Platform}:
 Linux i686 {libc=glibc}
 Linux x86_64 {libc=glibc}
 Linux aarch64 {libc=glibc}
 Linux armv7l {call_abi=eabihf, libc=glibc}
 Linux powerpc64le {libc=glibc}
 Linux i686 {libc=musl}
 Linux x86_64 {libc=musl}
 Linux aarch64 {libc=musl}
 Linux armv7l {call_abi=eabihf, libc=musl}
 macOS x86_64
 FreeBSD x86_64
 Windows i686
 Windows x86_64

julia> triplet.(supported_platforms())
13-element Vector{String}:

The triplet of the platform is used name of the tarball generated.

For some packages, (cross-)compilation may not be possible for all those platforms, or you have interested in building the package only for a subset of them. Examples of packages built only for some platforms are

  • libevent;
  • Xorg_libX11: this is built only for Linux and FreeBSD systems, automatically filtered from supported_platforms, instead of listing the platforms explicitly.

Expanding C++ string ABIs or libgfortran versions

Building libraries is not a trivial task and entails a lot of compatibility issues, some of which are detailed in Tricksy Gotchas.

You should be aware of two incompatibilities in particular:

  • The standard C++ library that comes with GCC can have one of two incompatible ABIs for std::string, an old one usually referred to as C++03 string ABI, and a newer one conforming to the 2011 C++ standard.


    This ABI does not have to do with the C++ standard used by the source code, in fact you can build a C++03 library with the C++11 std::string ABI and a C++11 library with the C++03 std::string ABI. This is achieved by appropriately setting the _GLIBCXX_USE_CXX11_ABI macro.

    This means that when building with GCC a C++ library or program which exposes the std::string ABI, you must make sure that the user whill run a binary matching their std::string ABI. You can manually specify the std::string ABI in the compiler_abi part of the platform, but BinaryBuilder lets you automatically expand the list of platform to include an entry for the C++03 std::string ABI and another one for the C++11 std::string ABI, by using the expand_cxxstring_abis function:

    julia> using BinaryBuilder
    julia> platforms = [Platform("x86_64", "linux")]
    1-element Array{Linux,1}:
     Platform("x86_64", "linux"; libc="glibc")
    julia> expand_cxxstring_abis(platforms)
    2-element Array{Platform,1}:
     Linux(:x86_64, libc=:glibc, compiler_abi=CompilerABI(cxxstring_abi=:cxx03))
     Linux(:x86_64, libc=:glibc, compiler_abi=CompilerABI(cxxstring_abi=:cxx11))

    Example of packages dealing with the C++ std::string ABIs are:

    • GEOS: expands the the C++ std::string ABIs for all supported platforms;
    • Bloaty: builds the package only for some platforms and expands the C++ std::string ABIs;
    • libcgal_julia: builds only for platforms with C++11 std::string ABI.
  • The libgfortran that comes with GCC changed the ABI in a backward-incompatible way in the 6.X -> 7.X and the 7.X -> 8.X transitions. This means that when you build a package that will link to libgfortran, you must be sure that the user will use a package linking to a libgfortran version compatible with their own. Also in this case you can either manually specify the libgfortran version in the compiler_abi part fo the platform or use a function, expand_gfortran_versions, to automatically expand the list of platform to include all possible libgfortran versions:

    julia> using BinaryBuilder
    julia> platforms = [Platform("x86_64", "linux")]
    1-element Array{Linux,1}:
     Platform("x86_64", "linux"; libc="glibc")
    julia> expand_gfortran_versions(platforms)
    3-element Array{Platform,1}:
     Linux(:x86_64, libc=:glibc, compiler_abi=CompilerABI(libgfortran_version=v"3.0.0"))
     Linux(:x86_64, libc=:glibc, compiler_abi=CompilerABI(libgfortran_version=v"4.0.0"))
     Linux(:x86_64, libc=:glibc, compiler_abi=CompilerABI(libgfortran_version=v"5.0.0"))

    Example of packages expanding the libgfortran versions are:

    • OpenSpecFun: expands the libgfortran versions for all supported platforms;
    • LibAMVW: builds the package only for some platforms and expands the libgfortran versions.

Don't worry if you don't know whether you need to expand the list of platforms for the C++ std::string ABIs or the libgfortran versions: this is often not possible to know in advance without thoroughly reading the source code or actually building the package. In any case the audit will inform you if you have to use these expand-* functions.

Platform-independent packages

BinaryBuilder.jl is particularly useful to build packages involving shared libraries and binary executables. There is little benefit in using this package to build a package that would be platform-independent, for example to install a dataset to be used in a Julia package on the user's machine. For this purpose a simple Artifacts.toml file generated with create_artifact would do exactly the same job. Nevertheless, there are cases where a platform-independent JLL package would still be useful, for example to build a package containing only header files that will be used as dependency of other packages. To build a platform-independent package you can use the special platform AnyPlatform:

platforms = [AnyPlatform()]

Within the build environment, an AnyPlatform looks like x86_64-linux-musl, but this shouldn't affect your build in any way. Note that when building a package for AnyPlatform you can only have products of type FileProduct, as all other types are platform-dependent. The JLL package generated for an AnyPlatform is platform-independent and can thus be installed on any machine.

Example of builders using AnyPlatform:


The products are the files expected to be present in the generated tarballs. If a product is not found in the tarball, the build will fail. Products can be of the following types:

The audit will perform a series of sanity checks on the products of the builder, with the exclusion FileProducts, trying also to automatically fix some common issues.

You don't need to list as products all files that will end up in the tarball, but only those you want to make sure are there and on which you want the audit to perform its checks. This usually includes the shared libraries and the binary executables. If you are also generating a JLL package, the products will have some variables that make it easy to reference them. See the documentation of JLL packages for more information about this.

Packages listing products of different types:

Binary dependencies

A build script can depend on binaries generated by another builder. A builder specifies dependencies in the form of previously-built JLL packages:

# Dependencies of Xorg_xkbcomp
dependencies = [
  • Dependency specify a JLL package that is necessary to build and load the current builder;
  • BuildDependency is a JLL package necessary only to build the current package, but not to load it. This dependency will not be added to the list of the dependencies of the generated JLL package.

The argument of Dependency and BuildDependency can also be a Pkg.PackageSpec, with which you can specify more details about the dependency, like a version number, or also a non-registered package. Note that in Yggdrasil only JLL packages in the General registry can be accepted.

The dependencies will be installed under ${prefix} within the build environment.

In the wizard, dependencies can be specified with the prompt: Do you require any (binary) dependencies? [y/N].

Examples of builders that depend on other binaries include:

  • Xorg_libX11 depends on Xorg_libxcb_jll, and Xorg_xtrans_jll at build- and run-time, and on Xorg_xorgproto_jll and Xorg_util_macros_jll only at build-time.

Version number of dependencies

There are two different ways to specify the version of a dependency, with two different meanings:

  • Dependency("Foo_jll", v"1.2.3"): the second argument of Dependency specifies the version of the package to be used for building: this version is not reflected into a compatibility bound in the project of the generated JLL package. This is useful when the package you want to build is compatible with all the versions of the dependency starting from the given one (and then you don't want to restrict compatibility bounds of the JLL package), but to maximize compatibility you want to build against the oldest compatible version.
  • Dependency(PackageSpec(; name="Foo_jll", version=v"1.2.3")): if the package is given as a Pkg.PackageSpec and the version keyword argument is given, this version of the package is used for the build and the generated JLL package will be compatible with the provided version of the package. This should be used when your package is compatible only with a single version of the dependency, a condition that you want to reflect also in the project of the JLL package.

Building and testing JLL packages locally

As a package developer, you may want to test JLL packages locally, or as a binary dependency developer you may want to easily use custom binaries. Through a combination of dev'ing out the JLL package and creating an overrides directory, it is easy to get complete control over the local JLL package state.

Overriding a prebuilt JLL package's binaries

After running pkg> dev LibFoo_jll, a local JLL package will be checked out to your depot's dev directory (on most installations this is ~/.julia/dev) and by default the JLL package will make use of binaries within your depot's artifacts directory. If an override directory is present within the JLL package directory, the JLL package will look within that override directory for binaries, rather than in any artifact directory. Note that there is no mixing and matching of binaries within a single JLL package; if an override directory is present, all products defined within that JLL package must be found within the override directory, none will be sourced from an artifact. Dependencies (e.g. found within another JLL package) may still be loaded from their respective artifacts, so dependency JLLs must themselves be dev'ed and have override directories created with files or symlinks created within them.

Auto-populating the override directory

To ease creation of an override directory, JLL packages contain a dev_jll() function, that will ensure that a ~/.julia/dev/<jll name> package is dev'ed out, and will copy the normal artifact contents into the appropriate override directory. This will result in no functional difference from simply using the artifact directory, but provides a template of files that can be replaced by custom-built binaries.

Note that this feature is rolling out to new JLL packages as they are rebuilt; if a JLL package does not have a dev_jll() function, open an issue on Yggdrasil and a new JLL version will be generated to provide the function.

Building a custom JLL package locally

When building a new version of a JLL package, if --deploy is passed to build_tarballs.jl then a newly-built JLL package will be deployed to a GitHub repository. (Read the documentation in the Command Line section or given by passing --help to a build_tarballs.jl script for more on --deploy options). If --deploy=local is passed, the JLL package will still be built in the ~/.julia/dev/ directory, but it will not be uploaded anywhere. This is useful for local testing and validation that the built artifacts are working with your package.