140 lines
4.3 KiB
Text
140 lines
4.3 KiB
Text
cdist-stages(7)
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===============
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Nico Schottelius <nico-cdist--@--schottelius.org>, Steven Armstrong <steven-dist--@--armstrong.cc>
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NAME
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----
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cdist-stages - Stages used during configuration deployment
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DESCRIPTION
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-----------
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Starting the execution of deployment with cdist-deploy-to(1), cdist passes
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through different stages, each can be triggered and debugged on its own.
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Reading the source of the cdist-deploy-to and cdist-object-run-all executables
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shows the scripts responsible for each stage.
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STAGE 0: INTERNAL PREPERATION
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-----------------------------
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Before running the user facing stages, cdist prepares the target host
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to contain cdist binaries and creates a clean environment for the
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configuration run.
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Related documentation:
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- Source of cdist-deploy-to
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STAGE 1: TARGET INFORMATION RETRIEVAL
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--------------------------------------
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In this stage information is collected about the target host using so called
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explorers. Every existing explorer is run on the target and the output of all
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explorers are copied back into the local cache. The results can be used by
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manifests and types.
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Related documentation:
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- cdist-explorer-run-global(1)
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- cdist-remote-explorer-run(1)
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- cdist-explorer(7)
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STAGE 2: RUN THE INITIAL MANIFEST
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---------------------------------
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The initial manifest, which should be used for mappings of hosts to types,
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is executed. This stage creates objects in a cconfig database that contains
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the objects as defined in the manifest for the specific host. In this stage,
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no conflicts may occur, i.e. no object of the same type with the same id may
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be created.
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Related documentation:
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- cdist-manifest-run-init(1)
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- cdist-manifest-run(1)
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- cdist-manifest(7)
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STAGE 3: OBJECT INFORMATION RETRIEVAL
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-------------------------------------
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Every object is checked whether its type has explorers and if so, these are
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transfered to the target host and executed. The results are transfered back
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and can be used in the following stages to decide what changes need to made
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on the target to implement the desired state.
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Related documentation:
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- cdist-object-explorer-run(1)
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- cdist-remote-explorer-run(1)
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- cdist-type(7)
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- cdist-explorer(7)
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STAGE 4: RUN THE OBJECT MANIFEST
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--------------------------------
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Every object is checked whether its type has a manifest file. If the type has
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a manifest file and it is executable, it will be executed. The manifest script
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may generate and change the created objects. In other words, one type can reuse
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other types.
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For instance the object __apache/www.test.ch is of type __apache, which may
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contain a manifest script, which creates new objects of type __file.
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The newly created objects are merged back into the existing tree. No conflicts
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may occur during the merge. A conflict would mean that two different objects
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try to create the same object, which indicates a broken configuration.
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Related documentation:
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- cdist-object-manifest-run(1)
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- cdist-manifest-run(1)
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- cdist-type(7)
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STAGE 5: CODE GENERATION
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------------------------
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In this stage for every created objects its type is checked whether it has a
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gencode script. If the type has a gencode script and it is executable it will
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be executed. This executable should create code to be executed on the target
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on stdout. If the gencode executable fails, it must print diagnostic messages
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on stderr and exit non-zero.
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Related documentation:
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- cdist-object-gencode-run(1)
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- cdist-object-gencode(1)
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- cdist-type(7)
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STAGE 6: CODE EXECUTION
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-----------------------
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For every object the resulting code from the previous stage is transferred to
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the target host and executed there to apply the configuration changes.
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Related documentation:
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- cdist-object-code-run(1)
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- cdist-code-run(1)
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STAGE 7: CACHE
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--------------
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The cache stores the information from the current run for later use.
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Related documentation:
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- cdist-cache(1)
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SUMMARY
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-------
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If, and only if, all the stages complete without an errors, the configuration
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will be applied to the target. Each stage can also be run individually, though
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dependencies for each stage must be fulfilled and thus the stages must be run
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in correct order.
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SEE ALSO
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--------
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- cdist(7)
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- cdist-deploy-to(1)
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- cdist-reference(7)
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COPYING
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-------
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Copyright \(C) 2010-2011 Nico Schottelius, Steven Armstrong. Free use of this software is
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granted under the terms of the GNU General Public License version 3 (GPLv3).
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