Ocsigen Server

Ocsigen Server is a powerful and modular generic purpose Web Server. It supports static files, redirections, reverse proxy, CORS, user pages with local configuration, page compression, authentication, etc.

Ocsigen Server can be used:

• as an executable: it reads its configuration from a file and dynamically loads the extensions and libraries you need for your sites,
• or as a library: build your own executable and statically link your the modules you need for your pages.

It is written in OCaml and uses the Cohttp library.

Installation

The easier way to install Ocsigenserver is to use the opam package manager. Ocsigen Server is also available in Linux distributions.

Quick start: serving a directory in one command

To serve the static files of a directory without writing any configuration file, just give the directory to ocsigenserver:

ocsigenserver ./public

This starts a server on port 8080 serving the files of ./public. No configuration file and no log directory are needed: the logs go to the terminal. A few options are available:

ocsigenserver --serve ./public --port 8000 --directory-listing

You can also start a reverse proxy that forwards every request to another server, again without any configuration file:

ocsigenserver --reverse-proxy http://localhost:9000 --port 8080

This is the simplest way to get started. For anything more elaborate (several hosts, extensions, fine-grained reverse proxy rules, etc.) use a configuration file or the library API, as described below.

Using Ocsigen Server as an executable

Create your configuration file. You can take this one as an example:

<ocsigen>
  <server>
    <port>8080</port>

    <logdir>local/var/log/mysite</logdir>
    <datadir>local/var/data/mysite</datadir>
    <charset>utf-8</charset>

    <commandpipe>local/var/run/mysite-cmd</commandpipe>
    <extension findlib-package="ocsigenserver.ext.staticmod"/>
    <host hostfilter="*">
      <static dir="local/var/www/mysite/" />
    </host>
  </server>
</ocsigen>

Update the paths to match your configuration and create the missing directories. Then run:

ocsigenserver -c <name of your configuration file>

Personalising your configuration

Have a look at the page Configuration to learn how to personalise the configuration file and adapt it to your needs.

Using Ocsigen Server as a library

If you want to include a Web Server in your OCaml app, add library ocsigenserver and the extensions you need (here ocsigenserver.ext.staticmod) in your Dune file:

(executable
 (public_name myapp)
 (name main)
 (libraries
  ocsigenserver
  ocsigenserver.ext.staticmod))

Call function Ocsigen.Server.start like this to run the server:

let _ =
  Ocsigen.Server.start
    [ Ocsigen.Server.host [Staticmod.run ~dir:"local/var/www/mysite/" ()]]

The server runs on port 8080 by default. Customise this using optional parameters of function Ocsigen.Server.start

Extensions

Depending on the features you need, you can extend the server by loading some modules.

The extensions provided are:

• Staticmod: for serving static pages,
• Accesscontrol: if you need to restrict the access to the sites,
• Eliom: if you want to use dynamic Web and mobile applications written in OCaml with Eliom,
• Revproxy: if you want to redirect some requests to another Web server,.
• Redirectmod: if you want to define some HTTP redirections,
• Deflatemod: if you want to compress the content before sending your pages,
• Outputfilter: allows to change the header of the HTTP response,
• Securityheaders: adds common security-related HTTP headers (HSTS, nosniff, X-Frame-Options, CSP),
• Rewritemod: allows to rewrite the request before continuing,
• Extendconfiguration: adds many useful configuration options,
• Authbasic: for basic HTTP authentication,
• CORS: for settings CORS options,
• Userconf: for allowing local users to have personal pages,

If you are using a configuration, file, use tag <extension/> to load an exetnsion (see examples in the manual of each extension). Most extension have configuration options, and define new tags for the configuration file.

If you are building a static executable, load the extensions as any library from your Dune file. Have a look at the API documentation of each documentation to see the functions it defines and the configuration options.

API reference

See the API reference for all the modules, functions and configuration options provided by Ocsigen Server and its extensions.

Upgrading from an earlier version

Ocsigen Server 8.0 renamed its modules and modernised its base library. See Migrating to Ocsigen Server 8.0 for the details and for the ocsigenserver-compat package that eases the transition.

Running on port 80 or 443

It is not recommended to run a Web server as root. If you want to use priviledged ports (port numbers less than 1024), like 80 or 443, you can add the capability to ocsigenserver with:

setcap 'cap_net_bind_service=+ep' <path to the server executable>

If something goes wrong

If something goes wrong, first have a look in the logs to see if there is an error message. The directory of logs is set in the configuration file or through option ?logdir of function Ocsigen.Server.start ($OPAM_SWITCH_PREFIX/lib/ocsigenserver/var/log/ocsigenserver by default).

If you cannot solve your problem, if you find a bug, a mistake in the documentation (even a small one), or if you want to make a suggestion, open an issue on Github.