54 lines
1.5 KiB
ReStructuredText
54 lines
1.5 KiB
ReStructuredText
Explorer
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========
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Description
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-----------
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Explorers are small shell scripts, which will be executed on the target
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host. The aim of each explorer is to give hints to types on how to act on the
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target system. An explorer outputs the result to stdout, which is usually
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a one liner, but may be empty or multi line especially in the case of
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type explorers.
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There are general explorers, which are run in an early stage, and
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type explorers. Both work almost exactly the same way, with the difference
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that the values of the general explorers are stored in a general location and
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the type specific below the object.
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Explorers can reuse other explorers on the target system by calling
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::
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$__explorer/<explorer_name> (general and type explorer)
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or
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::
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$__type_explorer/<explorer name> (type explorer).
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In case of significant errors, the explorer may exit non-zero and return an
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error message on stderr, which will cause cdist to abort.
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You can also use stderr for debugging purposes while developing a new
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explorer.
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Examples
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--------
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A very simple explorer may look like this::
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hostname
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Which is in practise the **hostname** explorer.
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A type explorer, which could check for the status of a package may look like this:
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.. code-block:: sh
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if [ -f "$__object/parameter/name" ]; then
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name="$(cat "$__object/parameter/name")"
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else
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name="$__object_id"
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fi
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# Expect dpkg failing, if package is not known / installed
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dpkg -s "$name" 2>/dev/null || exit 0
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