Building

Building dentOS

This section will explain how to build dentOS from source.

Structure

The build system repository structure is as follows:

• builds/ - contains architecture-specific configuration files
• docker/ - contains Docker configurations for all available builds (e.g. Debian 8, Debian 9 builds)
• docs/ - contains documentation
• make/ - contains make rules
• packages/ - contain package configuration, custom patches, etc.
• tools/ - contains scripts which drive the build system

DentOS binaries can be obtaining by downloading pre-built binaries, which are available at https://nexus.dent.dev/content/repositories/releases/org/dent/1.0 or by manually compiling from source. Compilation from source, being more time and resource demanding, has some advantages, such as that it enables us to include additional package [1] or drop others from the default configuration. We can also change various environment variables, such as compilation flags to optimize the built binaries for a selected architecture while on the other hand pre-built binaries and images are built generically and can't be customized in detail.

dentOS uses the Docker environment inside which the build process is executed. As already mentioned, compilation is a resource intensive process. Officially supported platform for building images is the Debian Linux distribution (versions 8-10), although generic compilation inside a Docker container should work on any Linux Distribution (assuming Docker is setup properly). Detailed instructions on how to install and configure Docker engine on Debian Linux can be found here. dentOS uses Dockerized Buildroot-like Makefiles where integration is based on the direct Makefile inclusion. Many custom Python scripts are used to drive the build in the ./tools directory. Before executing a target, the top-level Makefile include ./make/config.mk file. Entrypoint to the build system is a python script in ./tools/docker/onlbuilder. This build system is capable of building a ONIE-compatible installer. Currently supported architectures are:

• amd64
• arm (armel and armhf)
• arm64
• ppc

To start the build process is it enough to invoke the make command inside a local copy of the repository.

~ $ git clone https://github.com/dentproject/dentOS.git
~ $ cd dentOS
~ $ make docker

This will by default build a Debian 9 based image. In order to build an image which is based on the different Debian version we can specify the VERSION variable in the make command,:

# build a Debian 8 based image
~ $ make docker VERSION=8

Note that when setting up the Docker engine, it is often necessary to add your user to the “docker” group. This will enable using docker for non-privileged users.

[1] https://packages.debian.org/stable/