This fixes some perpetual diffs I saw in Atlas AccTests where an empty
map (`map[string]interface{}{}`) was being `d.Set` for "metadata_full".
Because the MapFieldWriter was not distinguishing between empty and nil,
this trigger the "map delete" logic and no count was written to the
state. This caused subsequent plans to improperly report a diff.
Here we redefine the map delete functionality to explicitly trigger only
on `nil`, so we catch the `.#` field for empty maps.
This was actually quite nasty as the first bug covered the second one…
The first bug is with HasChange. This function uses reflect.DeepEqual
to check if two instances are the same/have the same content. This
works fine for all types except for Set’s as they contain a function.
And reflect.DeepEqual will only say the functions are equal if they are
both nil (which they aren’t in a Set). So in effect it means that
currently HasChange will always say true for Set’s, even when they are
actually being equal.
As soon as you fix this problem, you will notice the second one (which
the added test is written for). Without saying you want the exact diff,
you will end up with a merged value which will (in most cases) be the
same.
Run all unit tests and a good part of the acc tests to verify this
works as expected and all look good.
This is a refactored solution for PR #616. Functionally this is still
the same change, but it’s implemented a lot cleaner with less code and
less changes to existing parts of TF.
This fixes a seemingly minor issue (GH-255) around plans showing changes
when in fact there are none. But in reality this turned out to uncover a
really terrible bug.
The effect of what was happening was that multiple items in a set were
being merged. Now, they were being merged in the right order, so if you
didn't have rich types (lists in a set) then you never saw the effect
since the later value would overwrite the earlier. But with lists (such
as in security groups), you would end up with the lists merging. So, if
you had one ingress rule with CIDR blocks and one with SGs, then after
the merge both ingress rules would have BOTH CIDR and SGs, resulting in
an incorrect plan (GH-255).
This fixes the issue by introducing a `getSourceExact` bitflag to the
ResourceData source. When this is set, ALL data must come from this
level, instead of merging lower levels. In the case of sets and diffs,
this is exactly what you want: "Get me the set 'foo' from the config and
the config ONLY (not the state or diff or w/e)".
Andddddd its fixed.
GH-255
Mitchell Hashimoto