Introduction
This article describes one solution to transfer a folder and all of its contents recursively with cdist to target hosts. I am motivated to do so, because I want to have one central place to configure the tftproot that I may use on a variety of KVM hosts.
Traditionally, it is not an easy job to handle recursive transfer correctly and efficiently in a configuration management system. Using a sophisticated tool like rsync or unison makes life usually way easier.
If you just have a minor number of files, like I have in this case, doing a recursive copy with cdist may be the easist way.
Copying the files recursively
Cdist knows about the types __file and __directory for file transfer and directory management. The type __nico_tftp_root, which can be found in the cdist-nico git repository (below cdist/conf/type) recursively copies all files it contains to the folder /home/service/tftp. Only when a file is changed, it is transferred again (the __file type takes care of this).
The manifest
In cdist, a manifest of a type defines, which other types to use. A manifest file is essentially shell code that can call other cdist types.
To accomplish the task, first of all the base directory is created on the remote site:
basedir=/home/services/tftp
__directory "$basedir" --mode 0755
Afterwards, I change into the source directory and find all files. Cdist exports the variable "__type" to access the folder in which the type is stored.
cd "$__type/files"
for file in $(find . | sed 's;./;;' | grep -v '^\.$' ); do
The grep command is needed, to skip the current directory, that is returned by find.
Now, for every file I determine the remote file name. Furthermore dependencies to the required directories are setup: You can require another type to be run before a type, by setting up the require environment variable (this will be changed in cdist 2.1. and replaced in 2.2, but there is still some time until this happens).
The remote name is constructed by this line:
name="$basedir/$file"
And the requirement is setup using this line:
# Require the previous directory in the path
export require="__directory/${name%/*}"
The shell (!) knows about string manipulation: ${variablename%/*} replaces the shortest matching suffix that equals "/*". And thus the previous statement removes the last part of the path (also known as dirname).
If the file found by find is a file, we call the __file type, if the file is actually a directory, the __directory type is called:
if [ -d "$file" ]; then
__directory "$name" --mode 0755
else
__file "$basedir/$file" --source "$__type/files/$file" \
--mode 0644
fi
done
And that's it - a full recursive copy with just a bunch of lines.