BinDeps.jl

Easily build binary dependencies for Julia packages

FAQ

Since there seems to be a lot of confusion surrounding the package systems and the role of this package, before we get started looking at the actual package, I want to answer a few common questions:

What is BinDeps?

BinDeps is a package that provides a collection of tools to build binary dependencies for Julia packages.
Do I need to use this package if I want to build binary dependencies for my Julia package?

Absolutely not! The system is designed to give the maximum amount of freedom to the package author in order to be able to address any situation that one may encounter in the real world. This is achieved by simply evaluating a file called deps/build.jl (if it exists) in a package whenever it is installed or updated. Thus the following might perhaps be the simplest possible useful build.jl script one can imagine:

    run(`make`)

I want to use BinDeps, but it is missing some functionality I need
(e.g. a package manager)

Since BinDeps is written in Julia it is extensible with the same ease as the rest of Julia. In particular, defining new behavior, e.g. for adding a new package manger, consists of little more than adding a type and implementing a couple of methods (see the section on Interfaces) or the RPMmd package for an example implementation.
I like the runtime features that BinDeps provides, but I don't really want to use its build time capabilities. What do you recommend?

The easiest way to do this is probably just to declare a BuildProceess for all your declared dependencies. This way, your custom build process will be called whenever there is an unsatisfied library dependency and you my still use the BinDeps runtime features.
Is there anything I should keep in mind when extending BinDeps or writing my own build process?

BinDeps uses a fairly standard set of directories by default and if possible, using the same directory structure is advised. Currently the specified directory structure is:

	deps/
		build.jl 		# This is your build file
		downloads/  	# Store any binary/source downloads here
		builds/		
			dep1/		# out-of-tree build for dep1, is possible
			dep2/   	# out-of-tree build for dep2, is possible
		    ...
		src/		
			dep1/   	# Source code for dep1
			dep2/		# Source code for dep2
			...
		usr/			# "prefix", install your binaries here
			lib/		# Dynamic libraries (yes even on Windows)
			bin/		# Excecutables
			include/	# Headers
			...

The high level interface - Declaring dependencies

To get a feel for the high level interface provided by BinDeps, have a look at a real-world example, namely the build script from the Cairo package. That build script uses almost all the features that BinDeps currently provides and is a great overview, but let's take it apart, to see exactly what's going on.

As you can see Cairo depends on a lot of libraries that all need to be managed by this build script. Every one of these library dependencies is introduced by the library_dependency function. The only required argument is the name of the library, so the following would be an entirely valid call:

	foo = library_dependency("libfoo")

However, you'll most likely quickly run into the issue that this library is named differently on different systems, which is why BinDeps provides the handy aliases keyword argument. So suppose our library is sometimes known as libfoo.so, but other times as libfoo-1.so or libfoo-1.0.0.dylib or even libbar.dll on windows, because the authors of the library decided to punish windows uses. In either case, we can easily declare all these in our library dependency:

	foo = library_dependency("libfoo",aliases=["libfoo","libfoo-1","libfoo-1.0.0","libbar"])

So far so good! There are a couple of other keyword arguments that are currently implemented and many more will most likely be added as necessary. The ones that are currently used are:

os = OS_NAME Limits this dependency to certain operating systems. The same could be achieved by using the operating specific macro, but this setting applies to all uses of this dependency and avoids having to wrap all uses of this dependency in macros. Note that the os parameter must match the value of Base.OS_NAME on the target platform with the special exception that :Unix matches all Unix-like platforms (e.g. Linux, Mac OS X, FreeBSD) As an example, consider this line from the Cairo build script:

	gettext = library_dependency("gettext", aliases = ["libgettext", "libgettextlib"], os = :Unix)

depends = [dep1,dep2] Currently unused, but in the future will be used to keep track of the dependency graph between binary dependencies to allow parallel builds. E.g.:

	cairo = library_dependency("cairo", aliases = ["libcairo-2", "libcairo"], depends = [gobject,fontconfig,libpng])

runtime::Bool Whether or not to consider this a runtime dependency. This means it's absence will not trigger an error at runtime (and it will not be loaded), but if it cannot be found at buildtime it will be installed (useful for build-time) dependencies of other binary dependencies.
validate::Function You may pass a function to validate whether or not a certain library is usable, e.g. whether or not has the correct version. To do so, pass a function that takes (name,handle) as an argument and returns true if the library is usable and false it not. The name argument is either an absolute path or the library name if it is a global system library, while the handle is a handle that may be passed to ccall or dlsym to check library symbols or the return value of function. Note however that it is invalid to store the handle. Instead, use the @load_dependencies macro (see below). Should the validation return false for a library that was installed by a provider, the provider will be instructed to force a rebuild.

The high level interface - Declaring build mechanisms

Alright, now that we have declared all the dependencies that we need let's tell BinDeps how to build them. One of the easiest ways to do so it to use the system package manger. So suppose we have defined the following dependencies:

	foo = library_dependency("libfoo")
	baz = library_dependency("libbaz")

And let's suppose that these libraries are available in the libfoo-dev and libbaz-dev in apt-get and that both libraries are installed by the libbaz yum package. We may declare this as follows:

	provides(AptGet,{
		"libfoo-dev" => foo,
		"libbaz-dev" => baz,
	})
	provides(Yum,"libbaz",[foo,baz])
}

One may remember the provides function by thinking AptGet provides the dependencies foo and baz.

The basic signature of the provides function is

	provides(Provider, data, dependency, options...)

where data is provider-specific (e.g. a string in all of the package manager cases) and dependency is the return value from `library dependency. As you saw above multiple definitions may be combined into one function call as such:

	provides(Provider,{data1=>dep1, data2=>dep2},options...)

which is equivalent to (and in fact will be internally dispatched) to:

	provides(Provider,data1,dep1,options...)
	provides(Provider,data2,dep2,options...)

If one provide satisfied multiple dependencies simultaneously, dependency may also be an array of dependencies (as in the Yum case above).

There are also several builtin options. Some of them are:

os = OS_NAME

This provider can only satisfy the library dependency on the specified os. This argument takes has the same syntax as the os keyword argument to
library_dependency.

The high level interface - built in providers

We have already seen the AptGet, and Yum providers, which all take a string naming the package as their data argument. The other build-in providers are:

Sources

Takes a URI object as its data argument and declared that the sources may be downloaded from the provided URI. This dependency is special, because it's success does not automatically mark the build as succeeded (in BinDeps terminology, it's a "helper"). By default this provider expects the unpacked directory name to be that of the archive downloaded. If that is not the case, you may use the :unpacked_dir option to specify the name of the unpacked directory, e.g.

provides(Sources,URI("http://libvirt.org/sources/libvirt-1.1.1-rc2.tar.gz"),libvirt,
		unpacked_dir="libvirt-1.1.1")

Binaries

If given a URI object as its data argument, indicates that the binaries may be downloaded from the provided URI. It is assumed that the binaries unpack the libraries into usr/lib. If given a String as its data argument, provides a custom search path for the binaries. A typical use might be to allow the user to provide a custom path by using an environmental variable.
BuildProcess

Common super class of various kind of build processes. The exact behavior depends on the data argument. Some of the currently supported build processes are:

 	Autotools(;options...)

Download the sources (as declared by the "Sources" provider) and attempt to 
install using Autotools. There is a plethora of options to change the behavior of 
this command. See the appropriate section of the manual (or even better, read the 
code) for more details on the available options.

SimpleBuild

A subclass of BuildProcess that takes any object that's part of the low-level interface and could be passed to run and simply executes that command.

The high level interface - Loading dependencies

BinDeps provides the @BinDeps.load_dependencies macro that you may call early in initialization process of your package to load all declared libraries in your build.jl file.

The basic usage is very simple:

using BinDeps
@BinDeps.load_dependencies

This will make all your libraries available as variables named by the names you gave the dependency. E.g. if you declared a dependency as

	library_dependency("libfoo")

The libfoo variable will now contain a reference to that library that may be passed to ccall or similar functions.

If you only want to load a subset of the declared dependencies you may pass the macro a list of libraries to load, e.g.

@BinDeps.load_dependencies [:libfoo, :libbar]

if you do not want to change the names of the variables that these libraries get stored in, you may use

@BinDeps.load_dependencies [:libfoo=>:_foo, :libbar=>:_bar]

which will assign the result to the _foo and _bar variables instead.

The low level interface

The low level interface provides a number of utilities to write cross platform build scripts. It looks something like this (from the Cairo build script):

	@build_steps begin
		GetSources(libpng)
		CreateDirectory(pngbuilddir)
		@build_steps begin
			ChangeDirectory(pngbuilddir)
			FileRule(joinpath(prefix,"lib","libpng15.dll"),@build_steps begin
				`cmake -DCMAKE_INSTALL_PREFIX="$prefix" -G"MSYS Makefiles" $pngsrcdir`
				`make`
				`cp libpng*.dll $prefix/lib`
				`cp libpng*.a $prefix/lib`
				`cp libpng*.pc $prefix/lib/pkgconfig`
				`cp pnglibconf.h $prefix/include`
				`cp $pngsrcdir/png.h $prefix/include`
				`cp $pngsrcdir/pngconf.h $prefix/include`
			end)
		end
	end

All the steps are executed synchronously. The result of the `@build_steps` macro 
may be passed to run to execute it directly, thought this is not recommended other
than for debugging purposes. Instead, please use the high level interface to tie 
the build process to dependencies. 

Some of the builtin build steps are:

FileDownloader(remote_file,local_file)

Download a file from remote_file create it as local_file
FileUnpacker(local_file,folder)

Unpack the file local_file into the folder folder
AutotoolsDependency(opts...)

Invoke autotools. Use of this build step is not recommended. Use the high level
interface instead
CreateDirectory(dir)

Create the directory dir
ChangeDirectory(dir)

cd into the directory dir and try to remain there for this build block. Must be the first command in a @build_steps block and will remain active for the entire block
MakeTargets([dir,],[args...],env)

Invoke make with the given arguments in the given directory with the given environment.
DirectoryRule(dir,step)

If dir does not exist invoke step and validate that the directory was created
FileRule([files...],step)

Like Directory rule, but validates the existence of any of the files in the files array`.
GetSources(dep)

Get the declared sources from the dependency dep and put them in the default download location