obuild

A parallel, incremental and declarative build system for OCaml.

Design

The goal is to make a very simple build system for users and developers of OCaml library and programs.

obuild acts as building black box: user declare only what they want to build and with which sources, and it will be consistently built. The design is based on Haskell's Cabal, and borrow most of the layout and way of working, adapting parts where necessary to support OCaml fully.

There's no way to build things that obuild has not been designed to do on purpose, so that the experience provided is consistent, and all future improvements to obuild will automatically benefit program and libraries using older versions. Currently unsupported features should be requested on the Github issue tracker.

Feature

• Incremental & parallel build system. only rebuilding what's necessary.
• Content-digest based staleness: rebuilds are driven by what actually changed, not file timestamps, with early cutoff (an implementation-only change does not recompile dependents whose interfaces are unchanged).
• Descriptive configuration file.
• Easy for users: no rules to mess about, just describe what you want.
• No building dependency apart from OCaml's stdlib: easy to build
• No tool or binary dependencies apart from ocaml compilers
• OCamlfind-like support integrated for faster compilation
• Wrapped libraries (pack: true): a library's modules namespaced under a single top-level module, so different libraries can reuse module names
• Vendored sub-projects (vendor-dirs:): build against obuild projects checked into your tree (e.g. git submodules) without installing them
• obuild run: build and run an executable in one step
• Generates .merlin automatically for IDE support

How to build a project using obuild

obuild supports a clean, user-friendly command-line interface with helpful error messages and automatic help generation.

Quick Start

# Get help
obuild -h                    # Show all available commands
obuild build -h              # Show build-specific options

# Check version
obuild --version

# Typical workflow
obuild configure --build-tests true
obuild build
obuild test

Available Commands

obuild configure    Prepare to build the package
obuild build        Make this package ready for installation
obuild run          Build an executable (if needed) and run it
obuild clean        Clean up after a build
obuild install      Install this package
obuild test         Run the tests
obuild doc          Generate documentation
obuild sdist        Generate a source distribution file (.tar.gz)
obuild init         Initialize a new project
obuild get          Get project metadata field
obuild generate     Generate configuration files (merlin, opam, completions)

Command Details

configure - Prepare the project by checking dependencies and setting build options

obuild configure [OPTIONS]

Options:
  --build-tests true|false        Build tests
  --build-examples true|false     Build examples
  --library-bytecode true|false   Compile libraries as bytecode
  --library-native true|false     Compile libraries as native
  -g                              Enable debugging symbols
  --annot                         Generate .annot files

build - Build every buildable target defined by the project

obuild build [OPTIONS] [TARGETS...]

Options:
  -j, --jobs N               Maximum number of parallel jobs (default: auto-detected)
  --dot                      Dump dependency graphs as .dot files

Examples:
  obuild build                # Build everything
  obuild build -j 4          # Build with 4 parallel jobs
  obuild build mylib myexe   # Build specific targets only

run - Build an executable target if it is stale, then run it

obuild run [EXE] [ARGS...]

# with a single executable in the project the name can be omitted;
# everything after the executable name is passed to the program verbatim
obuild run
obuild run myexec --port 8080

The program inherits the terminal and its exit code is propagated.

clean - Remove all build artifacts

test - Run all test targets

obuild test [OPTIONS]

Options:
  --output                   Show test output (default: only show failures)

install - Install libraries and executables

obuild install [OPTIONS]

Options:
  --destdir DIR              Override installation directory
  --opam                     Generate .install file for OPAM

get - Retrieve project metadata

obuild get FIELD

Fields: name, version, license

Examples:
  obuild get name            # Get project name
  obuild get version         # Get project version

Global Options

These options work with any command:

-v, --verbose              Verbose output
-q, --quiet                Quiet mode (errors only)
--color                    Enable colored output
--strict                   Enable strict mode

Configuration Files

Obuild supports configuration files for setting default values. Config files use a simple key = value format.

Config file locations (in order of precedence):

1. ./.obuildrc - Project-specific settings
2. ~/.obuildrc - User-wide settings

Example config file:

# ~/.obuildrc - User configuration for obuild

# Set default number of parallel jobs
jobs = 8

# Enable colored output by default
color = true

# Verbose mode
verbose = false

Supported options:

• jobs - Default number of parallel build jobs (integer)
• color - Enable colored output (true/false)
• verbose - Verbose output mode (true/false)
• quiet - Quiet mode (true/false)
• strict - Strict mode (true/false)

Command-line arguments always override config file values.

Shell Completion

Obuild can generate shell completion scripts for bash, zsh, and fish:

# Generate and install bash completion
obuild completion bash > ~/.bash_completion.d/obuild
source ~/.bash_completion.d/obuild

# Generate zsh completion
obuild completion zsh > ~/.zsh/completions/_obuild

# Generate fish completion
obuild completion fish > ~/.config/fish/completions/obuild.fish

How to write a project file

A project file is a file terminated by the .obuild extension. Only one per project is supported.

The content is declarative using a simple layout format. Every normal line needs to be in a "key: value" format. Multiple lines are supported by indenting (with spaces) the value related to the key.

    name: myproject
    version: 0.0.1
    description:
      This is my new cool project
      .
      This is a long description describing properly what the project does.
    licence: MyLicense
    authors: John Doe <john@doe.com>
    obuild-ver: 1
    homepage: http://my.server.com/myproject

The different target types:

• executable: this creates an executable that is going to be installed by default.
• library: create a library that is going to be installed.
• test: create an executable that will not be installed, and will interact with obuild according to the test_type field. cabal test will run every built tests in a row. for the exit test_type, the exit code is used to signal error (0 = success, anything else = failure)
• bench: create an executable that will not be installed, and will allow to benchmarks, some part of the project. This is largely unimplemented and just a placeholder for future development.
• example: create an executable that is not installed, nor compiled by default. you need to use configure with --enable-examples. This allow to make sure that examples are compiled with the sources to prevent bitrotting. At a later stage that can be used to generate extra documentation.

Declaring an executable

    executable myexec
      main-is: mymain.ml
      src-dir: src
      build-deps: unix

Declaring a library

    library mylib
      modules: Module1, Module2
      src-dir: lib
      build-deps: mydep1, mydep2

Wrapped libraries (pack)

Adding pack: true to a library namespaces all of its modules under a single top-level module named after the library:

    library mylib
      modules: Util, Core
      src-dir: lib
      pack: true

Consumers see Mylib.Util and Mylib.Core; the bare names are hidden, so two libraries may both define a module Util without clashing. Inside the library, modules refer to each other by their plain names. On OCaml >= 4.02 this is implemented with module aliases (dune-style Mylib__Util units, cheap incremental builds); on older compilers it falls back to -pack. The project syntax is the same either way.

Without pack: true, a module name may only be defined once per project: obuild reports a clear error when two targets provide the same module name from different source files.

Vendored sub-projects

    name: myproject
    ...
    vendor-dirs: vendor

Each entry of vendor-dirs either is a vendored obuild project directory or contains project directories (vendor/*/x.obuild — the layout produced by git submodules). The libraries of vendored projects are built as part of your project (their build-deps resolve against other vendored or project libraries first, then ocamlfind) and are not installed: they link into your artifacts. Vendored executables and tests are ignored. Vendored projects must themselves be obuild projects.