180 lines
5.2 KiB
Text
180 lines
5.2 KiB
Text
Rethinking ideas of last talk.
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What if types are formal / have formal arguments?
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What if cdist can do all the parsing stuff and the real
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functionality comes out of the library (similar to cfengine)?
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What if the library is integral part of cdist?
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conf/lib/$name/
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attributes/
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a
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b
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c
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I'm not sure whether this design is in fact helpful.
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But it's clearly necessary to have a directory per type, so a type can
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have helpers.
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conf/lib/$name/
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init?
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Prepare some very minimal (non functional) framework for library integration?
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Like parsing for command line arguments?
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Real configurations versus types:
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Types are reusable code: For instance etc_resolv.
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Configurations are types used and configured.
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Style
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__type <id> --option1 <arg1>
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<id> = everything your filesystem permits, but may not start with a period (".").
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If <id> == ., it setups the standard attributes.
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seems to be quite good usable. cdist can easily -----parse--- this.
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Nope. We don't parse. We let the shell execute.
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So whatever is __type will get executed.
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__type must probably be part of some cdist specific path.
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Which again could be
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conf/lib/$name
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Which could result in the directory
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conf/lib/.$name for helpers
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That style could include a mandority --help, --args arguments
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and would thus be independent of the language used (can, but does
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not must be shell).
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How to solve standard configurations that way?
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EASY AS WELL!
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__type <either option or magic> --option1 <arg1>
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for instance
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__type . --option1 <arg1>
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Type paths
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At least (at maximum)? 2:
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user + system
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Easy to do.
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Types: Name types types or name types modules?
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Where to place/start the configuration?
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wherever it is: name it configuration!
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cdist installation / paths:
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/etc/cdist/ # CDISTBASEDIR
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config/ # CDISTCONFIGDIR
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types/ # CDISTUSERTYPEDIR
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$prefix/lib/cdist/types/ # CDISTSYSTYPEDIR
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cdist environment:
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$__loaded_from # path where $type has been loaded from
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PATH=$CDISTUSERTYPEDIR:$CDISTSYSTYPEDIR:$PATH
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Recommendation (not a must):
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Put helpers for types into the typedir/.$typename
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All types should be prefixed by "__" to prevent clashes with the system
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binaries.
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Type commands (__bla) could get generated by cdist and cdist could use that
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to generate the actual cconfig part.
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This leads up to the next section
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How to write my own type named "coffee":
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Create the directory /etc/cdist/types/coffee/
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Create the file /etc/cdist/types/coffee/README containing a description of the type.
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If your type supports attributes, create the directory /etc/cdist/types/coffee/attributes.
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For each attribute, create the file
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/etc/cdist/types/coffee/attributes/$attribute_name which contains
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a short description on the first line
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then a blank line
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then a long description (probably over several lines)
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If you think your type may be useful for others, submit it for inclusion
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into cdist at cdist -- at -- l.schottelius.org.
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Create /etc/cdist/types/coffee/init which reads $configinput
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(either via cconfig or via environment) and outputs a block of
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shell code suitable for running on the client.
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cdist exec steps:
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- check for valid types, abort if user (re-)defined system types
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- generate __type binaries (aliases?), which contains cdist logic
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to analyse types and check for correct arguments
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- execute /etc/cdist/config/init (MAIN CONFIG) which in turn
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calls __type binaries
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- __type binaries (which are all the same, multicall!) generate
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cconfig
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- Run real type/init binaries with respective cconfig dir as path,
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which must generate shellcode to be executed.
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- Create the temporary shellscript containing all the code and execute
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it on the client.
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--------------------------------------------------------------------------------
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Support metaargs like --depends?
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If so, they need to be forbidden for types.
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Shell code generator:
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- use subshells for each shellcodeblock
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- create one main function (to ensure transfer is complete)
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Example:
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cdist_apply_$hostname()
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{
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# repeat this block for every type/id defined
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echo "Executing block from $type_$id ..."
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(
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code
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)
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}
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cdist_apply_$hostname
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