Belenios compilation instructions

The easy way

Belenios is written in OCaml and has some dependencies towards third-party OCaml libraries. The easiest and most portable way to compile Belenios from source is to use OPAM, which is a package manager for OCaml projects.

The non-OCaml prerequisites are:

These libraries and tools are pretty common, and might be directly part of your operating system. On Debian and its derivatives, they can be installed with the following command:

sudo apt install bubblewrap build-essential libgmp-dev libpcre3-dev pkg-config m4 libssl-dev libsqlite3-dev wget ca-certificates zip unzip aspcud libncurses-dev uuid-runtime zlib1g-dev libgd-securityimage-perl cracklib-runtime

If you are unfamiliar with OCaml or OPAM, we provide an shell script that creates a whole, hopefully self-contained, OCaml+OPAM install, and then installs all the dependencies of Belenios, everything into a single directory. You can choose the directory by setting the BELENIOS_SYSROOT environment variable, or it will take ~/.belenios by default. Just run:


On a modern desktop system, this needs approximately 20 minutes and 2.6 gigabytes of disk space.

If everything goes successfully, follow the given instructions to update your shell environment, then run:

make all

and you can skip the next two sections and go directly to the Documentation section.

You can also compile a debug version by using the BELENIOS_DEBUG environment variable:


Note that this version may introduce vulnerabilities and should not be used in production!

To make sure everything went well, you can run tests:

make check

If you are familiar with OCaml, please read the shell script, or the following two sections to compile Belenios with your existing OCaml installation.

Command-line tool

To compile the command-line tool, you will need:

With OPAM, these dependencies can be installed with the following command:

opam install atdgen zarith cryptokit uuidm cmdliner

Once all the dependencies have been installed, the command-line tool can be compiled with:


It produces a single executable, belenios-tool, in the _build/ directory. You can install it in your PATH (which we will assume in the guides), or refer to it with a full path.

Web server

The web server has the following additional dependencies:

With OPAM, you can install them with:

opam install calendar eliom csv

Once all the dependencies have been installed, the Eliom module can be compiled with:

make all

It will produce a single Eliom module, server.cma, in the _build/src/web directory. See demo/ for an ocsigenserver configuration template, and the Server administrator's guide for more information on how to use it.


To generate HTML files from .md ones, you will need:

Additionnaly, you will need LaTeX to compile the specification.

On Debian-based systems, you can install the dependencies needed to compile the documentation with:

sudo apt install markdown texlive-latex-extra texlive-fonts-recommended texlive-fonts-extra lmodern

Once all the dependencies have been installed, the documentation can be compiled with:

make doc

Compiling on Windows using Cygwin

Windows is not yet a fully supported platform, but you can compile at least the command-line tool on Windows + 32-bit Cygwin. You might need the following packages:

With these packages installed, you should be able to install OPAM by following its installation instructions from sources. Once OPAM is installed, follow the instructions in the Command-line tool section above.


Bootstrap fails if dune is already installed

The script fails when a not suitable version of dune is already installed in your $PATH. This is due to a bug in opam. If you face this issue, either uninstall dune before running, or manage to get opam running by other means, and directly use it to install the dependencies of Belenios.

Missing sources

The instructions outlined in this document and in the script imply downloading files from third-party servers. Sometimes, these servers can be down. For example, you can get:

=-=-= Installing ocamlnet.3.7.3 =-=-=
ocamlnet.3.7.3 Downloading
[ERROR] is not available

===== ERROR while installing ocamlnet.3.7.3 =====
Could not get the source for ocamlnet.3.7.3.

This can be worked around with the following steps:

Errors while compiling ocsigenserver

If ocsigenserver fails to install because of a SSL-related error:

An alternative could be to install aspcud before running

Errors while compiling Belenios itself

If you succeeded installing all dependencies, but you get errors while compiling Belenios, maybe you installed an incompatible version of a dependency. The script is tuned to install only compatible versions; you can have a look at it to get these versions.