This adds a "fragments" mode to the file resource. In addition to
"content" and "source", you can now alternatively build a file from the
file fragments of other files.
This might be slightly controversial, in that you must specify the state
if a file would need to be created to perform the action. We no longer
implicitly assume that just specifying content is enough. As it turns
out, I believe this is safer and more correct. The code to implement
this turns out to be much more logical and simplified, and does this
removes an ambiguous corner case from the reversed resource code.
Some discussion in: https://github.com/purpleidea/mgmt/issues/540
This patch also does a bit of related cleanup.
This adds the first reversible resource (file) and the necessary engine
API hooks to make it all work. This allows a special "reversed" resource
to be added to the subsequent graph in the stream when an earlier
version "disappears". This disappearance can happen if it was previously
in an if statement that then becomes false.
It might be wise to combine the use of this meta parameter with the use
of the `realize` meta parameter to ensure that your reversed resource
actually runs at least once, if there's a chance that it might be gone
for a while.
This patch also adds a new test harness for testing resources. It
doesn't test the "live" aspect of resources, as it doesn't run Watch,
but it was designed to ensure CheckApply works as intended, and it runs
very quickly with a simplified timeline of happenings.
This simple check should prevent some silly mistakes and make the logic
easier for other parts of the code that won't have to worry about this
pattern.
The default file state should be undefined. This is important because if
a reverse scenario that doesn't specify the state gets given this
default, it will be as if it was specified explicitly, which wouldn't
necessarily be what we want. Instead, an undefined state should
implicitly cause a file to get created if there's a reason to do so,
such as if content or another attribute is specified.
Hopefully this change doesn't introduce any bugs in the CheckApply code,
if it does, then it was due to a lack of implicit file creation.
This replaces the static obj.path and obj.isDir with live variants. I
don't know why I ever cared about caching these before, and if we ever
care we can memoize properly in the future.
This caused a small bug to actually be masked in the gob code. It is now
fixed in the previous commit.
Not sure how I let this in, but we should never do this. Hopefully the
Validate should catch this issue in advance, and if not, at least we'll
only error.
If the file res was defined with state => "exists" but no content
specified, it was not created. This patch fixes this bug and adds a test
and an example.
The engine core had some unfortunate bugs that were the result of some
early design errors when I wasn't as familiar with channels. I've
finally rewritten most of the bad parts, and I think it's much more
logical and stable now.
This also simplifies the resource API, since more of the work is done
completely in the engine, and hidden from view.
Lastly, this adds a few new metaparameters and associated code.
There are still some open problems left to solve, but hopefully this
brings us one step closer.
This patch fixes a previously undiscovered bug which prevented
the use of the source field in the file resource. CheckApply was
returning early if obj.Content was nil. It is also necessary to
check that obj.Source is empty before returning, otherwise
syncCheckApply never runs.
This giant patch makes some much needed improvements to the code base.
* The engine has been rewritten and lives within engine/graph/
* All of the common interfaces and code now live in engine/
* All of the resources are in one package called engine/resources/
* The Res API can use different "traits" from engine/traits/
* The Res API has been simplified to hide many of the old internals
* The Watch & Process loops were previously inverted, but is now fixed
* The likelihood of package cycles has been reduced drastically
* And much, much more...
Unfortunately, some code had to be temporarily removed. The remote code
had to be taken out, as did the prometheus code. We hope to have these
back in new forms as soon as possible.
