['Distribution oriented templating system', '=======================================', '', '', 'The problem this project tries to mitigate is "portable" scripting for variety', 'of operating systems (currently Linux distributions only) in the wild. While', 'writing an "universal" script, one needs to take into account small or bigger', 'differences among operating systems (like package installation tools, versions', 'of utilities, expected directories for binaries, libraries, etc.).', '', 'The *distgen* project is thus something like database of OS differences together', 'with convenience tool-set that allows you to instantiate valid script for', 'particular distribution. The concept is to have *template* file (mostly raw', 'jinja2 template) together with "declarative" *spec* file (YAML file) that', 'fulfils the needs of particular template.', '', 'You can find distgen documentation at http://distgen.readthedocs.io.', '', 'Download/Installation', '---------------------', '', 'Stable releases of distgen are available as RPMs in Fedora and EPEL', 'repositories, and in [pypi](https://pypi.python.org/pypi/distgen):', '', ' ```', ' $ sudo dnf install distgen', '', ' $ pip install distgen', ' ````', '', 'Development (git snapshot) RPMs are automatically built in [Fedora', 'Copr](https://copr.fedoraproject.org/coprs/praiskup/distgen).', '', 'You can also run development version directly from `git`, simply use the `dg`', 'shell wrapper available in this git root directory.', '', 'Example with Dockerfile', '-----------------------', '', 'Typical example is the need to instantiate working **FOO** package oriented', '**Dockerfile**s for all supported **Fedora/RHEL** versions.', '', 'To achieve that goal with distgen, you need to write something like', '`docker.tpl` template and `FOO.yaml` spec file. If the system-default', '`docker.tpl` template is good enough, its enough to write proper spec file:', '', '1. create `FOO.yaml` spec:', '', ' ```', ' $ cat FOO.yaml', ' maintainer: John Doe <jdoe@example.com>', ' parts:', ' pkginstall:', ' data:', ' - type: pkg', ' action: install', ' packages:', ' - vim', ' footer:', ' cmd: ["vim"]', ' ```', '', '2. Run `dg` tool to generate **Fedora 22** Dockerfile:', '', ' ```', ' $ dg --template docker.tpl \\', ' --spec FOO.yaml \\', ' --distro fedora-22-x86_64.yaml \\', ' > Dockerfile', ' $ cat Dockerfile', ' FROM index.docker.io/fedora:22', ' MAINTAINER John Doe <jdoe@example.com>', '', ' ENV container="docker"', '', ' RUN dnf -y --setopt=tsflags=nodocs install vim \\', " && dnf -y --setopt=tsflags=nodocs clean all --enablerepo='*'", '', ' CMD ["vim"]', ' ```', '', '3. Run `dg` tool again to generate **RHEL 7** dockerfile:', '', ' ```', ' $ dg --template docker.tpl \\', ' --spec FOO.yaml \\', ' --distro rhel-7-x86_64.yaml \\', ' > Dockerfile', ' $ cat Dockerfile', ' FROM registry.access.redhat.com/rhel7', ' MAINTAINER John Doe <jdoe@example.com>', '', ' ENV container="docker"', '', ' RUN yum -y --setopt=tsflags=nodocs install vim \\', " && yum -y --setopt=tsflags=nodocs clean all --enablerepo='*'", '', ' CMD ["vim"]', ' ```']
