svanderburg / disnix-stafftracker-nodejs-example

A REST/Node.js based toy system to test Disnix's deployment features

disnix-stafftracker-nodejs-example

This is an example case representing a system to manage staff of a university department. The system uses data stored in several databases. For each database, a REST interface is provided to retrieve and update records. A web application front-end is provided for end-users to retrieve and edit staff members.

Architecture

The above figure shows the architecture of this example, consisting of three layers. The data layer contains various Mongo databases storing data sets. The service layer provides RESTful web interfaces to the databases. The presentation layer contains a web application front-end which can be used by end users to manage staff of a university. The web application front-end is placed behind an nginx reverse proxy instance that caches the results of the requests to improve performance.

All the components in the figure are distributable components (or services) which can deployed to various machines in the network.

Usage

The deployment/DistributedDeployment sub folder contains all neccessary Disnix models, such as a services, infrastructure and distribution models required for deployment.

The models come in two variants:

• The standard variant, e.g. services.nix, infrastructure.nix and distribution.nix can be used to deploy services to a network of machines that already provide pre-deployed container services, e.g. MongoDB
• The self-contained variant, e.g. services-with-containers.nix, distribution-with-containers.nix deploy both the application services and their underlying container services, e.g. MongoDB, using the experimental Nix process management framework

Deployment using Disnix to a predeployed network of container services

For this scenario only installation of the basic Disnix toolset is required. First, you must manually install a network of machines running the Disnix service. Then you must adapt the infrastructure model to match to properties of your network and the distribution model to map the services to the right machines.

To deploy the databases you must install MongoDB. Check the instructions of your Linux distribution or the software distributions themselves how to install these system services. Dysnomia detects the presence of these system services and configures the corresponding modules to use them.

The system can be deployed by running the following command:

$ disnix-env -s services.nix -i infrastructure.nix -d distribution.nix

We can also deploy the system in which Nginx caches incoming requests:

$ disnix-env -s services-with-caching.nix -i infrastructure.nix -d distribution.nix

Deployment of the self-contained example with Disnix

It is also possible to deploy the self-contained example with the basic Disnix toolset:

$ disnix-env -s services-with-containers.nix -i infrastructure.nix -d distribution-with-containers.nix

To make the above example work, a network of machines that have the Disnix service installed are required with a infrastructure.nix model providing their connectivity settings.

Deployment using the NixOS test driver

This system can be deployed without adapting any of the models in deployment/DistributedDeployment. By running the following instruction, the variant without the proxy can be deployed in a network of virtual machines:

$ disnixos-vm-env -s services.nix -n network.nix -d distribution.nix

The variant with caching enabled can be deployed as follows:

$ disnixos-vm-env -s services-with-caching.nix -n network.nix -d distribution.nix

We can deploy the self-contained example (that also includes the container services) with:

$ disnixos-vm-env -s services-with-containers.nix -n network.nix -d distribution-with-containers.nix

Deployment using NixOps for infrastructure and Disnix for service deployment

It's also possible to use NixOps for deploying the infrastructure (machines) and let Disnix do the deployment of the services to these machines.

A virtualbox network can be deployed as follows:

$ nixops create ./network.nix ./network-virtualbox.nix -d vboxtest
$ nixops deploy -d vboxtest

The services can be deployed by running the following commands:

$ export NIXOPS_DEPLOYMENT=vboxtest
$ disnixos-env -s services.nix -n network.nix -d distribution.nix --use-nixops

The variant with caching enabled can be deployed as follows:

$ export NIXOPS_DEPLOYMENT=vboxtest
$ disnixos-env -s services-with-caching.nix -n network.nix -d distribution.nix --use-nixops

The variant with container services included can be deployed with:

$ export NIXOPS_DEPLOYMENT=vboxtest
$ disnixos-env -s services-with-containers.nix -n network.nix -d distribution.nix --use-nixops

Running the system

After the system has been deployed, open a web browser and type the following URL:

http://test1

The test1 hostname must be replaced by the real hostname of the machine to which the web application front-end is deployed. Check the distribution model for this. If the network expression is used included in this example, the third machine in the network machine automatically boots into IceWM and includes the Mozilla Firefox web browser for convenience.

License

This package is released under the MIT license.