Commit Graph

9 Commits

Author SHA1 Message Date
Gregory Haynes
5da7574aee Add get_elements; preserve backwards compat for expand_dependencies
expand_dependencies() was a public interface so we should try and
preserve backwards compat. However, since the interface is really
broken, add a new exported function "get_elements" that instack can
switch to.  This returns the canonical list of elements without
duplicates, and gives the path to each element too.

This highlighted that the unit tests were really a bit wrong.  They're
testing inner functions when we have an "API" in the get_elements()
function.  Convert all unit-tests to use this function instead.  Since
this is a library call, convert the sys.exit() calls to raised
exceptions.

Refactor the variable output into a separate function so we can do a
sanity check on it.

The added flake8 ignores are for the "over-indented for ... indent"
which happens a lot with these new longer lines.  Most other projects
ignore them.

This is an alternative proposal to
I15609389c18adf3017220fc94552514d195b323a

Change-Id: If97bcd21e45de1b5ed91023fdc441a4617051a6b
2016-12-20 08:18:59 +11:00
Ian Wienand
274be6de55 Making element overriding explicit
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
2016-09-08 10:58:19 +10:00
Ian Wienand
452f7b8d5a Clear up "already provided" message
I got quite confused what this was trying to tell me at first.  It's
saying that you requested an element but another element already
provides that element, so we don't know which one to choose.

To help clarify the situation to the user, keep track of what is
providing elements so we can describe where the conflict came from.

Change-Id: Ie7471ac900a8cbee5684c928badd1b8ce6d3e3cf
2016-07-01 11:53:07 +10:00
Ian Wienand
2b18513cad Convert element_dependencies to logging
Use standard logging module for output.  Add some basic testing of
error messages to the unit-tests.  Use the logging_config module to
setup the logging for interactive use.

Change-Id: Ia23722a7bd00aba336118edb155356a3b3ef6926
2016-06-28 16:02:45 +10:00
Gonéri Le Bouder
1011adf370 fail at startup with no operating-system element
Raise an error if there is no element with “operating-system”
in the element-provides file.

Change-Id: I2242537abc4c610252984c32c286bc6eb25de672
2014-06-12 11:19:20 +02:00
Monty Taylor
1c07d4ba1a Remove All Rights Reserved
The phrase is no longer needed as of August 23, 2000 with Nicaragua's
joining of the Berne Convention.

Additionally, in at least one instance,
elements/cache-url/bin/cache-url, its existence in the file between
Copyright lines is just weird and feels misleading, even though it is
not.

Remove all of the lines, because sanity.

Change-Id: I24fd76c2b4f66b8036010b5079db39ead729abee
2014-04-25 11:25:10 -07:00
Jon-Paul Sullivan
c357ca6634 Iterate over provided elements first
To ensure that we have the list of provided elements from the
command line before looking up dependencies, use a deque and
popleft() to take the elements on a first-in/first-out basis.

Change-Id: I0a2c21fa081763fd3cc8358be25dafeee1ed4718
Closes-Bug: #1303911
2014-04-07 18:04:00 +01:00
Jan Provaznik
604926b38f Adds "element-provides" support to element dependencies
An element can define a list of elements provided by itself. This allows
using an alternative element and keeping element dependencies at the
same time. This will be needed for example for mariadb element which will be
an alternative to mysql element - mysql dependency can be kept everywhere
but user can choose mariadb explicitly as a replacement by putting "mysql"
into "element-provides" file.

Change-Id: I7f193612f279dd71d9f1f1edfc60009838a00c5a
2014-03-25 15:35:52 +01:00
James Slagle
dee69b1810 Python code refactorings.
This commit refactors the python code in diskimage_builder slightly.  This is
in preparation for a larger review that adds more functionality to the python
code, namely the ability to apply elements to the current system as opposed to
a chroot.  Further, the refactorings can stand on their own for better clarity.
They include:
 - renaming elements.py to element_dependencies.py.  Adds clarity about the
   purpose of this module.
 - updating other code for this rename.
 - move tests into a tests submodule.

Change-Id: I5519cc52398e442b24e33802bae42070d64b0c1d
2013-11-12 10:47:57 -05:00