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doc: document override_defaults phase
override_defaults phase was added to devstack in [1]
but documentation was pending. This patch adds the
same. For history around override_defaults, one can
refer to the mail thread [2]
Also fixes a small typo
[1]: https://review.openstack.org/#/c/167933/
[2]: http://lists.openstack.org/pipermail/openstack-dev/2015-March/059621.html
Change-Id: I1b58ca0ce0e4b85a1dbd710b4c426606fd4dcf45
Deepak C Shetty authored on 2015/11/18 15:59:33Showing 2 changed files
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@@ -19,7 +19,16 @@ DevStack supports a standard mechanism for including plugins from |
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external repositories. The plugin interface assumes the following: |
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An external git repository that includes a ``devstack/`` top level |
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-directory. Inside this directory there can be 2 files. |
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+directory. Inside this directory there can be 3 files. |
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+ |
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+- ``override_defaults`` - a file containing global variables that |
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+ will be sourced before the lib/* files. This allows the plugin |
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+ to override the defaults that are otherwise set in the lib/* |
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+ files. |
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+ |
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+ For example, override_defaults may export CINDER_ENABLED_BACKENDS |
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+ to include the plugin-specific storage backend and thus be able |
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+ to override the default lvm only storage backend for Cinder. |
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- ``settings`` - a file containing global variables that will be |
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sourced very early in the process. This is helpful if other plugins |
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@@ -38,7 +47,7 @@ directory. Inside this directory there can be 2 files. |
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- ``plugin.sh`` - the actual plugin. It is executed by devstack at |
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well defined points during a ``stack.sh`` run. The plugin.sh |
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- internal structure is discussed bellow. |
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+ internal structure is discussed below. |
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Plugins are registered by adding the following to the localrc section |
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@@ -14,10 +14,13 @@ The scripts are sourced at the beginning of each script that calls them. The |
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entire `stack.sh` variable space is available. The scripts are |
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sourced with one or more arguments, the first of which defines the hook phase: |
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- source | stack | unstack | clean |
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+ override_defaults | source | stack | unstack | clean |
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- source: always called first in any of the scripts, used to set the |
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- initial defaults in a lib/* script or similar |
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+ override_defaults: always called first in any of the scripts, used to |
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+ override defaults (if need be) that are otherwise set in lib/* scripts |
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+ |
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+ source: called by stack.sh. Used to set the initial defaults in a lib/* |
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+ script or similar |
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stack: called by stack.sh. There are four possible values for |
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the second arg to distinguish the phase stack.sh is in: |