forked from ungleich-public/cdist
303 lines
9.1 KiB
ReStructuredText
303 lines
9.1 KiB
ReStructuredText
cdist type
|
|
==========
|
|
|
|
Description
|
|
-----------
|
|
Types are the main component of cdist and define functionality. If you
|
|
use cdist, you'll write a type for every functionality you would like
|
|
to use.
|
|
|
|
Synopsis
|
|
--------
|
|
|
|
.. code-block:: sh
|
|
|
|
__TYPE ID --parameter value [--parameter value ...]
|
|
__TYPE --parameter value [--parameter value ...] (for singletons)
|
|
|
|
|
|
How to use a type
|
|
-----------------
|
|
|
|
You can use types from the initial manifest or the type manifest like a
|
|
normal shell command:
|
|
|
|
.. code-block:: sh
|
|
|
|
# Creates empty file /etc/cdist-configured
|
|
__file /etc/cdist-configured --type file
|
|
|
|
# Ensure tree is installed
|
|
__package tree --state installed
|
|
|
|
A list of supported types can be found in the `cdist reference <cdist-reference.html>`_ manpage.
|
|
|
|
|
|
Singleton types
|
|
---------------
|
|
If a type is flagged as a singleton, it may be used only
|
|
once per host. This is useful for types which can be used only once on a
|
|
system. Singleton types do not take an object name as argument.
|
|
|
|
|
|
Example:
|
|
|
|
.. code-block:: sh
|
|
|
|
# __issue type manages /etc/issue
|
|
__issue
|
|
|
|
# Probably your own type - singletons may use parameters
|
|
__myfancysingleton --colour green
|
|
|
|
|
|
How to write a new type
|
|
-----------------------
|
|
A type consists of
|
|
|
|
- parameter (optional)
|
|
- manifest (optional)
|
|
- singleton (optional)
|
|
- explorer (optional)
|
|
- gencode (optional)
|
|
|
|
Types are stored below cdist/conf/type/. Their name should always be prefixed with
|
|
two underscores (__) to prevent collisions with other executables in $PATH.
|
|
|
|
To implement a new type, create the directory **cdist/conf/type/__NAME**.
|
|
|
|
|
|
Defining parameters
|
|
-------------------
|
|
Every type consists of required, optional and boolean parameters, which must
|
|
each be declared in a newline separated file in **parameter/required**,
|
|
**parameter/required_multiple**, **parameter/optional**,
|
|
**parameter/optional_multiple** and **parameter/boolean**.
|
|
Parameters which are allowed multiple times should be listed in
|
|
required_multiple or optional_multiple respectively. All other parameters
|
|
follow the standard unix behaviour "the last given wins".
|
|
If either is missing, the type will have no required, no optional, no boolean
|
|
or no parameters at all.
|
|
|
|
Default values for optional parameters can be predefined in
|
|
**parameter/default/<name>**.
|
|
|
|
Example:
|
|
|
|
.. code-block:: sh
|
|
|
|
echo servername >> cdist/conf/type/__nginx_vhost/parameter/required
|
|
echo logdirectory >> cdist/conf/type/__nginx_vhost/parameter/optional
|
|
echo loglevel >> cdist/conf/type/__nginx_vhost/parameter/optional
|
|
mkdir cdist/conf/type/__nginx_vhost/parameter/default
|
|
echo warning > cdist/conf/type/__nginx_vhost/parameter/default/loglevel
|
|
echo server_alias >> cdist/conf/type/__nginx_vhost/parameter/optional_multiple
|
|
echo use_ssl >> cdist/conf/type/__nginx_vhost/parameter/boolean
|
|
|
|
|
|
Using parameters
|
|
----------------
|
|
The parameters given to a type can be accessed and used in all type scripts
|
|
(e.g manifest, gencode, explorer). Note that boolean parameters are
|
|
represented by file existence. File exists -> True,
|
|
file does not exist -> False
|
|
|
|
Example: (e.g. in cdist/conf/type/__nginx_vhost/manifest)
|
|
|
|
.. code-block:: sh
|
|
|
|
# required parameter
|
|
servername="$(cat "$__object/parameter/servername")"
|
|
|
|
# optional parameter
|
|
if [ -f "$__object/parameter/logdirectory" ]; then
|
|
logdirectory="$(cat "$__object/parameter/logdirectory")"
|
|
fi
|
|
|
|
# optional parameter with predefined default
|
|
loglevel="$(cat "$__object/parameter/loglevel")"
|
|
|
|
# boolean parameter
|
|
if [ -f "$__object/parameter/use_ssl" ]; then
|
|
# file exists -> True
|
|
# do some fancy ssl stuff
|
|
fi
|
|
|
|
# parameter with multiple values
|
|
if [ -f "$__object/parameter/server_alias" ]; then
|
|
for alias in $(cat "$__object/parameter/server_alias"); do
|
|
echo $alias > /some/where/useful
|
|
done
|
|
fi
|
|
|
|
|
|
Input from stdin
|
|
----------------
|
|
Every type can access what has been written on stdin when it has been called.
|
|
The result is saved into the **stdin** file in the object directory.
|
|
|
|
Example use of a type: (e.g. in cdist/conf/type/__archlinux_hostname)
|
|
|
|
.. code-block:: sh
|
|
|
|
__file /etc/rc.conf --source - << eof
|
|
...
|
|
HOSTNAME="$__target_host"
|
|
...
|
|
eof
|
|
|
|
If you have not seen this syntax (<< eof) before, it may help you to read
|
|
about "here documents".
|
|
|
|
In the __file type, stdin is used as source for the file, if - is used for source:
|
|
|
|
.. code-block:: sh
|
|
|
|
if [ -f "$__object/parameter/source" ]; then
|
|
source="$(cat "$__object/parameter/source")"
|
|
if [ "$source" = "-" ]; then
|
|
source="$__object/stdin"
|
|
fi
|
|
....
|
|
|
|
|
|
Writing the manifest
|
|
--------------------
|
|
In the manifest of a type you can use other types, so your type extends
|
|
their functionality. A good example is the __package type, which in
|
|
a shortened version looks like this:
|
|
|
|
.. code-block:: sh
|
|
|
|
os="$(cat "$__global/explorer/os")"
|
|
case "$os" in
|
|
archlinux) type="pacman" ;;
|
|
debian|ubuntu) type="apt" ;;
|
|
gentoo) type="emerge" ;;
|
|
*)
|
|
echo "Don't know how to manage packages on: $os" >&2
|
|
exit 1
|
|
;;
|
|
esac
|
|
|
|
__package_$type "$@"
|
|
|
|
As you can see, the type can reference different environment variables,
|
|
which are documented in `cdist reference <cdist-reference.html>`_.
|
|
|
|
Always ensure the manifest is executable, otherwise cdist will not be able
|
|
to execute it. For more information about manifests see `cdist manifest <cdist-manifest.html>`_.
|
|
|
|
|
|
Singleton - one instance only
|
|
-----------------------------
|
|
If you want to ensure that a type can only be used once per target, you can
|
|
mark it as a singleton: Just create the (empty) file "singleton" in your type
|
|
directory:
|
|
|
|
.. code-block:: sh
|
|
|
|
touch cdist/conf/type/__NAME/singleton
|
|
|
|
This will also change the way your type must be called:
|
|
|
|
.. code-block:: sh
|
|
|
|
__YOURTYPE --parameter value
|
|
|
|
As you can see, the object ID is omitted, because it does not make any sense,
|
|
if your type can be used only once.
|
|
|
|
|
|
The type explorers
|
|
------------------
|
|
If a type needs to explore specific details, it can provide type specific
|
|
explorers, which will be executed on the target for every created object.
|
|
|
|
The explorers are stored under the "explorer" directory below the type.
|
|
It could for instance contain code to check the md5sum of a file on the
|
|
client, like this (shortened version from the type __file):
|
|
|
|
.. code-block:: sh
|
|
|
|
if [ -f "$__object/parameter/destination" ]; then
|
|
destination="$(cat "$__object/parameter/destination")"
|
|
else
|
|
destination="/$__object_id"
|
|
fi
|
|
|
|
if [ -e "$destination" ]; then
|
|
md5sum < "$destination"
|
|
fi
|
|
|
|
|
|
Writing the gencode script
|
|
--------------------------
|
|
There are two gencode scripts: **gencode-local** and **gencode-remote**.
|
|
The output of gencode-local is executed locally, whereas
|
|
the output of gencode-remote is executed on the target.
|
|
The gencode scripts can make use of the parameters, the global explorers
|
|
and the type specific explorers.
|
|
|
|
If the gencode scripts encounters an error, it should print diagnostic
|
|
messages to stderr and exit non-zero. If you need to debug the gencode
|
|
script, you can write to stderr:
|
|
|
|
.. code-block:: sh
|
|
|
|
# Debug output to stderr
|
|
echo "My fancy debug line" >&2
|
|
|
|
# Output to be saved by cdist for execution on the target
|
|
echo "touch /etc/cdist-configured"
|
|
|
|
Notice: if you use __remote_copy or __remote_exec directly in your scripts
|
|
then for IPv6 address with __remote_copy execution you should enclose IPv6
|
|
address in square brackets. The same applies to __remote_exec if it behaves
|
|
the same as ssh for some options where colon is a delimiter, as for -L ssh
|
|
option (see :strong:`ssh`\ (1) and :strong:`scp`\ (1)).
|
|
|
|
|
|
Variable access from the generated scripts
|
|
------------------------------------------
|
|
In the generated scripts, you have access to the following cdist variables
|
|
|
|
- __object
|
|
- __object_id
|
|
|
|
but only for read operations, means there is no back copy of this
|
|
files after the script execution.
|
|
|
|
So when you generate a script with the following content, it will work:
|
|
|
|
.. code-block:: sh
|
|
|
|
if [ -f "$__object/parameter/name" ]; then
|
|
name="$(cat "$__object/parameter/name")"
|
|
else
|
|
name="$__object_id"
|
|
fi
|
|
|
|
|
|
Hints for typewriters
|
|
----------------------
|
|
It must be assumed that the target is pretty dumb and thus does not have high
|
|
level tools like ruby installed. If a type requires specific tools to be present
|
|
on the target, there must be another type that provides this tool and the first
|
|
type should create an object of the specific type.
|
|
|
|
If your type wants to save temporary data, that may be used by other types
|
|
later on (for instance \__file), you can save them in the subdirectory
|
|
"files" below $__object (but you must create it yourself).
|
|
cdist will not touch this directory.
|
|
|
|
If your type contains static files, it's also recommended to place them in
|
|
a folder named "files" within the type (again, because cdist guarantees to
|
|
never ever touch this folder).
|
|
|
|
|
|
How to include a type into upstream cdist
|
|
-----------------------------------------
|
|
If you think your type may be useful for others, ensure it works with the
|
|
current master branch of cdist and have a look at `cdist hacking <cdist-hacker.html>`_ on
|
|
how to submit it.
|