This is a re-factor of element_dependencies to achieve two things --
centralising override policy and storing path names.
Firstly we want to make the override policy for elements completely
explicit. Currently, elements that wish to copy parts of other
elements walk ELEMENTS_PATH themselves and look for elements in
IMAGE_ELEMENT. How they handle duplicate elements can differ, leading
to inconsistent behaviour.
We introduce logic in element-info to find elements in each of the
directories in ELEMENT_PATHS in *reverse* order -- that is to say,
earlier entries in the paths will overwrite later ones.
For example
ELEMENT_PATHS=foo:bar:baz
will mean that "foo/element" will override "baz/element", since "foo"
is first. This should be sane to anyone familiar with $PATH.
Documentation is clarified around this point and a test-case is added.
The second thing is that we want to keep the complete path of the
elements we have chosen. We want the aforementioned elements that
walk the element list to use these canonical paths to pickup files;
this way they don't need to make local decisions about element
overrides, but can simply iterate a list and copy/merge files if they
exist.
A follow-on change (I7092e1845942f249175933d67ab121188f3511fd) will
expose this data in a separate variable that can be parsed by elements
(a further follow-on I0a64b45e9f2cfa28e84b2859d76b065a6c4590f0
modifies the elements to use this information). Thus this does not
change the status-quo -- elements that are walking ELEMENTS_PATH
themselves and can/will continue doing that.
Change-Id: I2a29861c67de2d25c595cb35d850e92807d26ac6
Icf8a075224833fcfbbe2128e8802ff41c39f3c09 looked rather ugly, and it's
easy for us to expand the processing done in the arch list.
Change "arch" to a comma-separated list of architectures that should
match for install.
Add a "not-arch" list which will exclude the package from installation
on those architectures. (An aside -- I considered making it just he
one list with foo,!bar,moo but ! has special meaning in YAML, so it's
easier to have two lists).
$ ARCH=ppc64 package-installs-squash --elements ironic-agent --path=./elements/ /dev/stdout | grep dmidecode
$ ARCH=ppc64 package-installs-squash --elements ironic-agent --path=./elements/ /dev/stdout | grep lshw
"lshw",
$ ARCH=amd64 package-installs-squash --elements ironic-agent --path=./elements/ /dev/stdout | grep lshw
$ ARCH=amd64 package-installs-squash --elements ironic-agent --path=./elements/ /dev/stdout | grep dmidecode
"dmidecode",
Change-Id: Ic69dd02a09e6f3ba9078a2377d8df29871a20db2
