cdist/docs/src/cdist-scan.rst
2021-07-10 21:02:27 +02:00

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Scan
=====
Description
-----------
Runs cdist as a daemon that discover/watch on hosts and reconfigure them
periodically. It is especially useful in netboot-based environment where hosts
boot unconfigured, and to ensure your infrastructure stays in sync with your
configuration.
This feature is still consider to be in **beta** stage, and only operate on
IPv6 (including link-local).
Usage (Examples)
----------------
Discover hosts on local network and configure those whose name is resolved by
the name mapper script.
.. code-block:: sh
$ cdist scan --beta --interface eth0 \
--mode scan --name-mapper path/to/script \
--mode trigger --mode config
List known hosts and exit.
.. code-block:: sh
$ cdist scan --beta --list --name-mapper path/to/script
Please refer to `cdist(1)` for a detailed list of parameters.
Modes
-----
The scanner has 3 modes that can be independently toggled. If the `--mode`
parameter is not specified, only `tigger` and `scan` are enabled (= hosts are
not configured).
trigger
Send ICMPv6 requests to specific hosts or broadcast over IPv6 link-local to
trigger detection by the `scan` module.
scan
Watch for incoming ICMPv6 replies and optionally configure detected hosts.
config
Enable configuration of hosts detected by `scan`.
Name Mapper Script
------------------
The name mapper script takes an IPv6 address as first argument and writes the
resolved name to stdout - if any. The script must be executable.
Simplest script:
.. code-block:: sh
#!/bin/sh
case "$1" in
"fe80::20d:b9ff:fe57:3524")
printf "my-host-01"
;;
"fe80::7603:bdff:fe05:89bb")
printf "my-host-02"
;;
esac
Resolving name from `PTR` DNS record:
.. code-block:: sh
#!/bin/sh
for cmd in dig sed; do
if ! command -v $cmd > /dev/null; then
exit 1
fi
done
dig +short -x "$1" | sed -e 's/.$//'