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authorLudovic Courtès <ludo@gnu.org>2015-10-14 15:48:14 +0200
committerLudovic Courtès <ludo@gnu.org>2015-10-14 21:39:05 +0200
commitd6c3267a32ae80b5a6f780a1678710ecc958b456 (patch)
tree63a2bc1b8ba582ee026ff453c2048e2730522044 /doc
parenta64cd7b65fc9ecf63035bd39e41f8cac5b8dc716 (diff)
downloadpatches-d6c3267a32ae80b5a6f780a1678710ecc958b456.tar
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guix system: Add 'extension-graph' command.
* guix/scripts/system.scm (service-node-label, service-node-type, export-extension-graph): New procedures. (guix-system)[parse-sub-command]: Add 'extension-graph'. Honor it. (show-help): Add 'extension-graph'. * doc/guix.texi (Invoking guix system): Document it. (Service Composition): Add cross-reference.
Diffstat (limited to 'doc')
-rw-r--r--doc/guix.texi28
1 files changed, 28 insertions, 0 deletions
diff --git a/doc/guix.texi b/doc/guix.texi
index 9956887b96..0e0e507714 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -6983,6 +6983,30 @@ KVM kernel module should be loaded, and the @file{/dev/kvm} device node
must exist and be readable and writable by the user and by the daemon's
build users.
+The @command{guix system} command has even more to offer! The following
+sub-commands allow you to visualize how your system services relate to
+each other:
+
+@anchor{system-extension-graph}
+@table @code
+
+@item extension-graph
+Emit in Dot/Graphviz format to standard output the @dfn{service
+extension graph} of the operating system defined in @var{file}
+(@pxref{Service Composition}, for more information on service
+extensions.)
+
+The command:
+
+@example
+$ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
+@end example
+
+produces a PDF file showing the extension relations among services.
+
+@end table
+
+
@node Defining Services
@subsection Defining Services
@@ -7015,6 +7039,7 @@ collects device management rules and makes them available to the eudev
daemon; the @file{/etc} service populates the system's @file{/etc}
directory.
+@cindex service extensions
GuixSD services are connected by @dfn{extensions}. For instance, the
secure shell service @emph{extends} dmd---GuixSD's initialization system,
running as PID@tie{}1---by giving it the command lines to start and stop
@@ -7035,6 +7060,9 @@ as arrows, a typical system might provide something like this:
At the bottom, we see the @dfn{boot service}, which produces the boot
script that is executed at boot time from the initial RAM disk.
+@xref{system-extension-graph, the @command{guix system extension-graph}
+command}, for information on how to generate this representation for a
+particular operating system definition.
@cindex service types
Technically, developers can define @dfn{service types} to express these