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Mirage is a programming framework for constructing secure, high-performance network applications across a variety of cloud computing and mobile platforms. Code can be developed on a normal OS such as Linux or MacOS X, and then compiled into a fully-standalone, specialised unikernel that runs under the Xen hypervisor. Since Xen powers most public cloud computing infrastructure such as Amazon EC2, this lets your servers run more cheaply, securely and finer control than with a full software stack.

The most up-to-date documentation can be found at the homepage, at The site is self-hosted and a useful example, available at Simpler skeleton applications are found at

This repository includes:

  • a commmand-line tool to create and deploy applications with Mirage.
  • in types/, a library of type signatures that compliant applications use.

There are several diverse backends in Mirage that require rather specialised build steps (from Javascript to Xen unikernels), and this complexity is wrapped up in the tool.

To work with Mirage, you'll need the following prerequisites installed:

  • a working OCaml compiler (4.01.0 or higher).
  • the OPAM source package manager (1.2.0 or higher).
  • an x86_64 or armel Linux host to compile Xen kernels, or FreeBSD, OpenBSD or MacOS X for the userlevel version.

There are three stages to using mirage:

  • a configuration phase where OPAM package dependencies are satisfied.

  • a build phase where the compiler and any support scripts are run.

  • a run phase where mirage spawns and tracks the progress of the deployment (e.g. as a UNIX process or a Xen kernel).

Configuration files

mirage currently uses a configuration file to build a Mirage unikernel. While we're documenting it all, please see the lib_test directory in this repository for the regression examples. The latest instructions are also to be found at

Configuring Mirage Applications

Provided that one and only one file of name <foo>.conf (where <foo> can be any string) is present in the current working directory, the command:

mirage configure

will configure your project. It will generate a Makefile and with the appropriate boilerplate for your chosen platform.

To configure for the unix-direct target (using tap interfaces), do:

mirage configure --unix

To build for the xen target, do:

mirage configure --xen

Once configuration is complete, you can install the OPAM packages required by this unikernel by:

make depend

Building Mirage Applications

The command:

mirage build

will build your project. Likewise, you can use the --unix or --xen switches to build for a particular target.

Running Mirage Applications

The command:

mirage run # [--unix or --xen]

will run the unikernel on the selected backend.

  • Under the unix-direct backend (--unix), mirage sets up a virtual interface (tap) is passes its fd to the unikernel that will use it to perform networking operations.

  • Under the xen backend (--xen), mirage creates a xl configuration file and uses xl to run the unikernel locally. Xen has to be installed and running on the machine.

Compiling to Xen and deploying to the cloud

In order to deploy a Mirage unikernel to Amazon EC2, you need to install the AWS tools on your machine, build a unikernel with the --xen option and then use the script (in directory script) in order to register you kernel with AWS. Then you can start your kernel with the web interface to AWS or any other mean AWS provides to start EC2 instances.