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Disnix
Disnix is a distributed service deployment extension for the Nix package manager.
Nix builds packages from Nix expressions and manages intra-dependencies on single systems. Disnix extends the Nix approach to distributed service-oriented systems by managing inter-dependencies of a distributed system and performs the distribution and activation of distributed system components.
It uses Nix expressions that capture the services, the infrastructure and the distribution of services to machines to automate the entire deployment process.
Prerequisites
In order to build Disnix from source code, the following packages are required:
When building directly from a Git clone, you also need:
To be able to build software with Disnix, Nix and Nixpkgs are required:
To run the Disnix service you need the following packages:
These dependencies can be acquired with the Nix package manager, your host system's package manager or be compiled from sources. Consult the documentation of your distribution or the corresponding packages for more information.
Installation
Disnix is a typical autotools based package which can be compiled and installed by running the following commands in a shell session:
$ ./configure
$ make
$ make install
When building from the Git repository, you should run the bootstrap script first:
$ ./bootstrap
For more information about using the autotools setup or for customizing the
configuration, take a look at the ./INSTALL file.
Disnix must be installed on a coordinator machine that initiates deployment as well as all target machines in the network to which service components can be deployed.
On the target machines, you must also run the disnix-service to make deployment
operations remotely accessible. The Disnix service requires a protocol wrapper
to actually do this. The default wrapper in the Disnix distribution is the SSH
wrapper. More information on this can be found in the Disnix manual.
Moreover, it also requires Dysnomia to be installed so that services can activated and deactivated.
The coordinator machine requires the presence of a copy of Nixpkgs to make
building of service components possible. In order to find the location of
Nixpkgs, the NIX_PATH environment variable must be refer to the location where
Nixpkgs is stored. This can be done by running the following command-line
instruction:
$ export NIX_PATH="nixpkgs=/path/to/nixpkgs"
On NixOS, this environment variable has already been configured.
Usage
In order to deploy a service-oriented system, a developer has to write Nix expressions that capture the services of which a distributed system consists, the infrastructure that descibes the machines in a network (including their properties) and a distribution of service components to machines in the network.
By invoking disnix-env with these Nix expressions as parameters, services are
automatically built from source code (including all its intra-dependencies),
distributed to the target machines and activated in the right order. In case of a
failure a rollback is performed:
$ disnix-env -s services.nix -i infrastructure.nix -d distribution.nix
See the tutorials on the webpage for more information on deploying a service-oriented system with Disnix.
Disnix itself has a modular architecture, which supports various extensions that can be used to make integration with the host environment better and deployment activities more convenient. Refer to the Disnix manual to see what extensions can be used.
Manual
Disnix has a nice Docbook manual that can be compiled yourself. However, it is also available online.
License
Disnix is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation either version 2.1 of the License, or (at your option) any later version. Disnix is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.