✨ Allow configuring a default cache selector #1710

alvaroaleman · 2021-11-01T15:23:52Z

It is already possible to configure cache selectors per gvk, but it is
not possible to default this selector for all types. This change adds
that.

Fixes #1708

alvaroaleman · 2021-11-01T16:28:51Z

/assign @joelanford @vincepri

joelanford · 2021-11-01T20:05:25Z

pkg/cache/cache.go

+// SelectorsByObjectDefaultKey can be used in SelectorsByObject to configure a default
+// selector for all kinds that do not have a specific selector set up.
+type SelectorsByObjectDefaultKey struct{ metav1.Object }
+
+// GetObjectKind implements runtime.Object.
+func (s *SelectorsByObjectDefaultKey) GetObjectKind() schema.ObjectKind {
+	return schema.EmptyObjectKind
+}
+
+// DeepCopyObject implements runtime.Object.
+func (s *SelectorsByObjectDefaultKey) DeepCopyObject() runtime.Object { return s }


Rather than encoding the default selector into the SelectorsByObject option which requires this new exported SelectorsByObjectDefaultKey type, is it possible to add a DefaultSelector field to the options struct and then handle the setup internally?

That's a great idea, updated the PR, PTAL

FillZpp

In fact, now we already have ObjectAll and GroupVersionKindAll.

In type DisableDeepCopyByObject map[client.Object]bool, If developers use ObjectAll as its key, it will be the default value. So how about reuse ObjectAll in SelectorsByObject to avoid defining a new option?

joelanford · 2021-11-04T15:55:01Z

@FillZpp Brings up a good point that there's already a mechanism for this with ObjectAll.

I'm torn though. On one hand, I think a separate Default* field is much better from a user discoverability standpoint. On the other, there is already precedent for storing the default value in the map with a special key.

Interested on folks thoughts about introducing Default* fields for all of these *ByObject maps?

alvaroaleman · 2021-11-05T21:03:31Z

In type DisableDeepCopyByObject map[client.Object]bool, If developers use ObjectAll as its key, it will be the default value. So how about reuse ObjectAll in SelectorsByObject to avoid defining a new option?

Right, that is where I got the idea from, I thought I remembered we did that but then couldn't find it :)

So tbh I am thorn as well, the UX of having a top-level field is much better than a magic key but does that warrant making things differently? Also I feel like the selector option warrants it because it is likely going to be used more than the somewhat exotic DisableDeepCopyByObject but I might be biased in that opinion as I need one but not the other.

To not get stuck in this question I would suggest to only add a magic key and not a top-level option for now. If we later find that ppl want to use this but have trouble finding the magic key we can still add a top-level option without breaking compatibility (by copying its value into the magic key entry). WDYT @joelanford ?

alvaroaleman · 2021-11-12T17:49:38Z

@joelanford could you have another look, please?

pkg/cache/cache.go

vincepri · 2021-11-15T19:49:29Z

pkg/cache/cache.go

+// Use SelectorsByObjectDefaultKey as key to specify a default selector that
+// will be used for all types that do not have a selector configured.


Is this comment still valid?

err after the back-and-forth regarding magic key vs config option I decided to use the magic key, as it is easy to add a config option later but not easy to remove it again: #1710 (comment)

Apparently I forgot to update the code though 😬 did that now.

I ended up not re-using the ObjectAll because it is a default that doesn't apply to everything, just to everything that doesn't have a setting so the name might cause confusion.

I ended up not re-using the ObjectAll because it is a default that doesn't apply to everything, just to everything that doesn't have a setting so the name might cause confusion.

Emm.. I'm confused that the default and all here seem to be the same semantics? They all mean the default configuration for all kinds of object, except the objects that have their specific values.

fabriziopandini · 2021-11-15T20:06:56Z

pkg/cache/cache.go

@@ -203,6 +209,7 @@ func convertToSelectorsByGVK(selectorsByObject SelectorsByObject, scheme *runtim
 		}
 		selectorsByGVK[gvk] = internal.Selector(selector)
 	}
+	selectorsByGVK[schema.GroupVersionKind{}] = internal.Selector(defaultSelector)


nit not blocking
const defalutSelectorKey = schema.GroupVersionKind{}

Needs to be a var but good idea, updated the code.

alvaroaleman · 2021-11-15T21:42:26Z

/retest
The failure seems unrelated

alvaroaleman · 2021-11-15T21:53:05Z

/retest

alvaroaleman · 2021-11-16T14:01:07Z

/retest

alvaroaleman · 2021-11-22T17:11:39Z

@joelanford @vincepri could you have another look, please?

vincepri · 2021-11-29T05:55:38Z

pkg/cache/cache_test.go

+			SelectorsByObject: cache.SelectorsByObject{
+				&corev1.ServiceAccount{}:             {Field: fields.OneTermEqualSelector("metadata.namespace", testNamespaceOne)},
+				&cache.SelectorsByObjectDefaultKey{}: cache.ObjectSelector{Field: fields.OneTermEqualSelector("metadata.namespace", testNamespaceTwo)},
+			},


Looking at how this is being used, if I understood what we're trying to do here correctly, we can summarize it as:

For objects of type ServiceAccount, always cache only the objects in namespace 1

For any other object, cache objects in namespace 2

If that's the case, I'm not super sure if I like this APIs, it's confusing that the fallback is also a "selector by object", which seems like a wildcard, although it could be confusing to users.

Have we thought instead of adding another option, like DefaultSelector, or similar?

@vincepri yes, see the discussion here: #1710 (comment)

I would suggest to not add and deprecate any magic key in favor of a different field, it makes a nicer UX and easier understanding of the codebase. Without this test/example, it wouldn't have been clear what the PR was trying to achieve and how.

Okay, reverted it back to add a top-level DefaultSelector field, ptal.

It is already possible to configure cache selectors per gvk, but it is not possible to default this selector for all types. This change adds that.

k8s-ci-robot · 2021-12-01T16:11:20Z

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✨ Allow configuring a default cache selector

0b60488

It is already possible to configure cache selectors per gvk, but it is not possible to default this selector for all types. This change adds that.

alvaroaleman force-pushed the default-selector branch from 9ee0603 to 0b60488 Compare November 29, 2021 16:19

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✨ Allow configuring a default cache selector #1710

✨ Allow configuring a default cache selector #1710

alvaroaleman commented Nov 1, 2021 •

edited

alvaroaleman commented Nov 1, 2021

joelanford Nov 1, 2021

alvaroaleman Nov 1, 2021

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joelanford commented Nov 4, 2021

alvaroaleman commented Nov 5, 2021

alvaroaleman commented Nov 12, 2021

vincepri Nov 15, 2021

alvaroaleman Nov 15, 2021

FillZpp Nov 16, 2021

fabriziopandini Nov 15, 2021

alvaroaleman Nov 15, 2021

alvaroaleman commented Nov 15, 2021

alvaroaleman commented Nov 15, 2021

alvaroaleman commented Nov 16, 2021

alvaroaleman commented Nov 22, 2021

vincepri Nov 29, 2021

alvaroaleman Nov 29, 2021

vincepri Nov 29, 2021

alvaroaleman Nov 29, 2021

k8s-ci-robot commented Dec 1, 2021

		// Use SelectorsByObjectDefaultKey as key to specify a default selector that
		// will be used for all types that do not have a selector configured.

✨ Allow configuring a default cache selector #1710

✨ Allow configuring a default cache selector #1710

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