129 lines
4.1 KiB
Text
129 lines
4.1 KiB
Text
This document is a brainstorming document,
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on how to integrate providers. Providers
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had been "type" in previous discussion.
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Proposed/discussed structures:
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1) 2010-11-02
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$basedir/$type/
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properties/
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name/
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required # required | optional
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choices # \n liste
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meta/
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default (shell script)
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providers/
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pukman/
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2) 2010-11-09
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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
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type.
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If your type supports attributes, create the directory /etc/cdist/types/coffee/
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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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--------------------------------------------------------------------------------
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provider layout:
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<name>/
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config # binary that is called to adjust cconfig tree
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change # binary that is called on the remote host?
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--------------------------------------------------------------------------------
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cdist view on providers:
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How providers are integrated/run:
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First stage:
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- If cdist encounters provider in manifest,
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a wrapper script is run, that creates a
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new entry in the cconfig database and adds
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attribute values. This defines a cconfig
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tree, that may look as follows:
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<hostname>/<provider>/<id>/<parameters>:
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myhost/__file/cdist_bin/source
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myhost/__file/cdist_bin/destination
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...
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- In this stage, no conflicts may occur, as
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no provider code has been called (i.e. only
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manifests, which map config to hosts is
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applied).
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Second stage:
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- The "manifest" script of every used provider
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(i.e. the manifests created at least one object)
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is called, which again is able to call other
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providers. All created objects may also be modified
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by the provider.
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For instance a "httpd" provider may call the
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"webroot" provider with --path / ...
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# FIND CASE WHERE SENSEFUL => look through
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current puppet config
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- The newly created objects are merged back into
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the existing tree. No conflicts may occur during
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the merge, because this would implicit that the
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provider conflicts with other providers.
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The idea of this that a provider may expand another
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provider with functionality, but may need to adjust
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("overwrite") settings from the original provider.
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Third stage:
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- Cdist calls the "gencode" binary of the providers
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for every created object. This binary should create
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code to be executed on the target on stdout.
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If the gencode binary fails, it must print diagnostic
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messages on stderr and exit non-zero.
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A description of what the generated code may/must/should
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do can be found at the end of this document.
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- Cdist merges together the generated code
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(taking care of DEPENDENCIES (which are not
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yet defined (take care, double nested brackets)))
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Fourth stage:
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- The resulting shell script is transferred
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to the target and executed.
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--------------------------------------------------------------------------------
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Scope of code execution on the client
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It should be assumed that the clients are pretty dumb
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and thus do not have high level tools like python
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installed.
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If a provider requires specific tools to be present
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on the target, there must be another provider that
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provides this tool and the first provider must create
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an object of the specific provider.
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If the generated code fails on the client, it must
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print diagnostistic messages on stderr and call
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"exit 1", so the configuration is aborted.
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