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115 lines
4.6 KiB
Markdown
115 lines
4.6 KiB
Markdown
# About
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This directory contains the source code for a tiny service supervision
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framework devised for the Pygos system, consisting of an init daemon,
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a small syslog daemon, a _definitely_ non standards compliant cron
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implementation and various command line utilities.
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The individual parts of the framework are designed to be independent of
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each other (for instance, the tiny syslogd is intended to work with *any*
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init system and other components of the framework don't depend on the presence
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of this *specific* syslog implementation) and everything that is not strictly
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part of the init system (such as the syslog daemon) can be disabled through
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the configure script.
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The programs of this package are developed first and foremost for GNU/Linux
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systems, so there are some GNU and some Linux extensions used and some of the
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code may unintentionally rely on Linux specific behavior.
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Nevertheless, if sufficient interest exists, it should be possible to make it
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run on BSDs or other Unix-like systems, but some effort may be required.
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The init system tries to mimic the concept of unit files from systemd as those
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were considered to be a good design choice.
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In a typical setup, the parameterizeable service description files are stored
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in `/usr/share/init` by default. Services are enabled by creating a symlink
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in `/etc/init.d`. This can be done more conveniently using the `service`
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command line tool.
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A default setup is provided, as needed for the Pygos system, including helper
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scripts for setting up mount points and for network configuration. If you want
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to use the init daemon for another system, you may have to toss out or adapt
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some of the default configuration and make your own.
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Right now, the system is in a "basically works" proof of concept stage and
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needs some more work to become usable.
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There are plans for *maybe* *eventually* adding more fancy features like
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support for Linux name spaces, seccomp filters and cgroups or network
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back ends for the syslog daemon, but right now, features are added only
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when the need arises.
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See [docs/init.md](docs/init.md) for more information on the design,
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implementation and caveats of the init daemon.
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See [docs/cmdline.md](docs/cmdline.md) for an explanation on the available
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command line tools.
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See [docs/services.md](docs/services.md) for more information on service
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description files.
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See [docs/network.md](docs/network.md) for information on how the network
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configuration works.
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See [docs/defconfig.md](docs/defconfig.md) for an explanation on the default
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services and configuration provided with this package.
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See [docs/usyslogd.md](docs/usyslogd.md) for details on the tiny syslog
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implementation.
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See [docs/gcron.md](docs/gcron.md) for details on the cron implementation.
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## Why
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There are already a bunch of similar projects out there that have been
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considered for use in the Pygos system. The reason for starting a new
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one was mainly dissatisfaction with the existing ones. Other Projects
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that have been considered include:
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- systemd
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Contains a lot of good ideas, but it is HUGE. It has tons of
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dependencies. It implements tons of things that it simply shouldn't.
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It has a horrid, "modern", python based, hipster build system.
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It's simply too damn large and complex.
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- SystemV init
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A bad combination of unnecessary complexity where it isn't needed and a
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complete lack of abstraction where it would be needed. Shell script
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copy and paste madness. There are reasons people started developing
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alternatives (other than "hurr-durr-parallel-boots").
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- upstart
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Seems nice overall, but needlessly big and complex for the intended
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use case in Pygos. Would have needlessly added D-Bus to the system.
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- OpenRC
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Was already integrated into Pygos. Things turned out to be broken.
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Upstream developers did not accept fixes (after ignoring them for weeks
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and preferring typo fixes instead). Complaints from other people who
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tried to contribute fixes were observed on GitHub. Complaints from
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package maintainers about deteriorating code quality were observed
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on the official IRC channel. Documentation is non-existent.
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- daemon tools and similar (runnit, s6, minit, ...)
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The sixties are over. And even code from that era is more readable. The
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source code for those projects should better be tossed out the window and
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rewritten from scratch. If you are a first semester CS student and you
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hand something like this in as a homework, the best you might get is a
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well deserved slap on the back of your head.
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- busybox init
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Nice and simple. Probably the best fit if the rest of your user space is
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busybox as well.
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