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doc: Mention Linux containers; emphasize reproducible builds.

* doc/guix.texi (Introduction): Use "containers" instead of "chroots".
  (Invoking guix-daemon): Add @cindex entries.  Mention the Linux
  container features.
  (Features): Add sentence on build reproducibility.
Ludovic Courtès 9 years ago
  1. 19


@ -95,7 +95,7 @@ always produces the same result when passed a given set of inputs. It
cannot alter the system's environment in
any way; for instance, it cannot create, modify, or delete files outside
of its build and installation directories. This is achieved by running
build processes in isolated environments (or @dfn{chroots}), where only their
build processes in isolated environments (or @dfn{containers}), where only their
explicit inputs are visible.
@cindex store
@ -224,6 +224,7 @@ The @code{guix-daemon} program may then be run as @code{root} with:
# guix-daemon --build-users-group=guix-builder
@end example
@cindex chroot
This way, the daemon starts build processes in a chroot, under one of
the @code{guix-builder} users. On GNU/Linux, by default, the chroot
@ -271,6 +272,10 @@ is normally run as @code{root} like this:
For details on how to set it up, @ref{Setting Up the Daemon}.
@cindex chroot
@cindex container, build environment
@cindex build environment
@cindex reproducible builds
By default, @command{guix-daemon} launches build processes under
different UIDs, taken from the build group specified with
@code{--build-users-group}. In addition, each build process is run in a
@ -278,7 +283,10 @@ chroot environment that only contains the subset of the store that the
build process depends on, as specified by its derivation
(@pxref{Programming Interface, derivation}), plus a set of specific
system directories. By default, the latter contains @file{/dev} and
@file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
@dfn{container}: in addition to having its own file system tree, it has
a separate mount name space, its own PID name space, network name space,
etc. This helps achieve reproducible builds (@pxref{Features}).
The following command-line options are supported:
@ -447,13 +455,18 @@ profiles, and remove those that are provably no longer referenced
generations of their profile so that the packages they refer to can be
@cindex reproducibility
@cindex reproducible builds
Finally, Guix takes a @dfn{purely functional} approach to package
management, as described in the introduction (@pxref{Introduction}).
Each @file{/nix/store} package directory name contains a hash of all the
inputs that were used to build that package---compiler, libraries, build
scripts, etc. This direct correspondence allows users to make sure a
given package installation matches the current state of their
distribution, and helps maximize @dfn{reproducibility}.
distribution. It also helps maximize @dfn{build reproducibility}:
thanks to the isolated build environments that are used, a given build
is likely to yield bit-identical files when performed on different
machines (@pxref{Invoking guix-daemon, container}).
@cindex substitute
This foundation allows Guix to support @dfn{transparent binary/source