Arbitrary vars in rule refs #5913

johanfylling · 2023-05-10T18:10:50Z

This PR adds the possibility to declare rules with variables at arbitrary locations int the ref; e.g.

package example

p[q].r[s] := 42 { q := "foo"; s := "bar" }

By default, the compiler won't allow rule refs to have vars in any other position than the last term; to enable general rule refs, set the OPA_ENABLE_GENERAL_RULE_REFS env var (any value). (is this the best way to do this, or do we have precedence of other ways of setting feature flags?)

Not included in this PR:

~~Feature flag to enable/disable~~
~~Partial eval~~
Planner implementation
~~Type-checker update~~
Language definition update in docs
~~fmt~~

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srenatus · 2023-05-31T11:15:15Z

ast/compile.go

@@ -311,6 +335,8 @@ func NewCompiler() *Compiler {
 		{"BuildComprehensionIndices", "compile_stage_rebuild_comprehension_indices", c.buildComprehensionIndices},
 	}

+	_, c.generalRuleRefsEnabled = os.LookupEnv("OPA_ENABLE_GENERAL_RULE_REFS")


Huh interesting 💡 yeah, why not. We might throw in a _WIP_

srenatus

Started looking at it. Still much ground to cover on my side 🔍

ast/index.go

ast/parser.go

test/cases/cases.go

topdown/exported_test.go

This is the topdown part of supporting generic refs. Fixes: open-policy-agent#5993 Signed-off-by: Johan Fylling <johan.dev@fylling.se>

srenatus

Sorry it took me so long to get back to this. Some comments and questions inside

srenatus · 2023-07-06T09:56:53Z

ast/parser.go

@@ -140,6 +142,7 @@ func NewParser() *Parser {
 		s:  &state{},
 		po: ParserOptions{},
 	}
+	_, p.po.generalRuleRefsEnabled = os.LookupEnv("OPA_ENABLE_GENERAL_RULE_REFS")


💭 treating the environment as a global variable is better avoided, but if we can keep this as a short-term stop-gap, it's probably OK.

This is temporary, and will be removed once general refs are feature complete. Hopefully soon 🤞. I'm open to improve this if it's too much of an eyesore, though 😅 .

srenatus · 2023-07-06T09:57:43Z

test/cases/testdata/refheads/test-arbitrary-var-refs.yaml

+        1: true
+      c:
+        2: true
+# FIXME: Below test case returns: rego_type_error: undefined ref: data.test.p.b


This has been solved in the type-checker update I have lined up: johanfylling/opa@jf/5685/multi-var-rule-refs...generic_refs/type-check

srenatus · 2023-07-06T09:59:18Z

test/cases/testdata/refheads/test-arbitrary-var-refs.yaml

+#
+#      p.q[r].s := 1 { r := "foo" }
+#      p.q[r].s := 2 { r := "bar" }
+#  query: i := ["foo", "bar"][_]; data.test.p.q[i].s = x


Maybe quotes help?

Suggested change

# query: i := ["foo", "bar"][_]; data.test.p.q[i].s = x

# query: 'i := ["foo", "bar"][_]; data.test.p.q[i].s = x'

Alternatively, you could query data.test.q and add

q = x { i := ["foo", "bar"][_] p.q[i].s = x }

Hm, looking at this again, I actually get a result with the expected parameters, but with some added "stuff":

{{"$0": 0, "__localq0__": ["foo", "bar"], "i": "foo", "x": 1}, {"$0": 1, "__localq0__": ["foo", "bar"], "i": "bar", "x": 2}}

If I change the query to data.test.p.q[i].s = x, I get a good result:

{{"i": "bar", "x": 2}, {"i": "foo", "x": 1}}

Is this expected, or perhaps an unwanted side effect of my changes 🤔 ? Will try a similar thing on main.

main exhibit the same behavior. Running opa eval does not output bindings for $0 and __localq0__; so maybe this is a side effect of how the test works?

Those should never make it out, I think; but opa eval might have some extra code to filter them. Or maybe that was the rego package, https://github.com/open-policy-agent/opa/blob/main/rego/rego.go#L2166-L2168

srenatus · 2023-07-06T10:02:24Z

topdown/eval.go

+
+func (e *eval) biunifyDynamicRef(pos int, a, b ast.Ref, b1, b2 *bindings, iter unifyIterator) error {
+	if pos >= len(a) || pos >= len(b) {
+		return iter()


So if they don't have the same length, but overlap, we'd accept that?

data.foo.bar = data.foo[x].z

we'd add x = "bar" to the bindings and go on?

But I might be missing something here, I haven't fully understood the topdown change yet.

We're simply binding any possibly known vars in a rule's ref before evaluating its body.

If data.foo.bar == data.foo.bar.z then I'd expect your snipped should evaluate. (is that even possible, though? 😵‍💫)

This is an interesting case to test for, though; hadn't thought about it from this angle before 🤔.

Perhaps a bit hacky test, but this should trigger this scenario:

package unification p := i { foo.bar.x.y = foo[i].z } foo[a][b] := c { a := "bar" c := { "x": { "y": 42 }, "z": 42 }[b] }

$ OPA_ENABLE_GENERAL_RULE_REFS=true opa eval -d . 'data.unification.p'

Or am I completely misunderstanding you?

srenatus · 2023-07-06T10:03:30Z

topdown/eval_test.go

+		//	`,
+		//	query: `i := ["foo", "bar"][_]; data.test.p.q[i].s = x`,
+		//	exp:   `[{"x": 1}, {"x": 2}]`,
+		//},


What's up with these? Do they not work yet; or have they been subsumed by the tests above...? 🤔

Ah, I missed un-commenting those. Fixed 👍 .

srenatus · 2023-07-06T10:07:49Z

topdown/eval.go

+		e.e.virtualCache.Put(hint.key, result)
+		return e.evalTerm(iter, e.pos+1, result, e.bindings)
+	}
+
 	for _, rule := range e.ir.Rules {


Given that generic ref head rules are the more general case, you might expect that the base case (below) is also covered by what's added above -- is that so? Or what am I missing?

I think you're right. These two branches should be possible to merge into one; given that there is no performance benefit to keeping them separate.

I think it's around here PE is breaking down too; so I'll dig around here a bit to see what improvements are necessary + possible.

It's even a bit broken as-is, given that this should be in an elseblock 😅 . I think this rule unification just won't contribute any data in applicable cases, so the result ends up being correct; but we're doing unnecessary work 🤔 .
Scratch that; I'm not even reading my own code right 😄 .

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

…ert()` Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Fixes: open-policy-agent#5994 Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

instead of `Or`:ing them Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Nested object created by general ref didn't maintain ground:ness even though containing vars. Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

… with dynamic portion of a rule ref Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

* Adding comments * Removing unused stuff * Rename evalOneDynamicRefRulePreUnify() -> evalOneRulePreUnify() Signed-off-by: Johan Fylling <johan.dev@fylling.se>

…l ref heads Signed-off-by: Johan Fylling <johan.dev@fylling.se>

srenatus

Checked the commits since last week, only had a few questions. It's great to see this progress 🚀

srenatus · 2023-08-24T09:41:34Z

format/testfiles/test_ref_heads.rego.formatted

@@ -17,3 +17,26 @@ r[x] if x := 10
 p.q.r[x] if x := 10

 p.q.r[2] = true
+
+g[h].i[j].k = true


This looks so wrong but h and j could be rules defined somewhere in the package, right? 😅 (Not that it matters for formatting)

True, this isn't internally consistent; but it's valid Rego, and for this rule we're more interested to see what the formatter does with the redundant { true } body.

topdown/eval_test.go

Conflicts: ast/env.go

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

ashutosh-narkar · 2023-08-29T17:53:19Z

ast/check_test.go

@@ -579,6 +687,7 @@ func TestCheckInferenceRules(t *testing.T) {
 				t.Fatalf("Unexpected error %v:", err)
 			}

+			fmt.Println(env.tree.String())


Left from testing probably.

Oops, yea 🤦‍♂️ 😄

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

srenatus

Nitpicks only. Yay, can't wait to get this in. Thanks for the hard work; it's like a summer project 😎

srenatus · 2023-08-31T07:22:19Z

ast/check_test.go

-					types.NewStaticProperty("c", types.B)},
-				nil,
+			expected: types.NewObject(nil,
+				types.NewDynamicProperty(types.S, types.Any{types.B, types.N, types.S}),


📝 took me a moment to understand this, but I had overlooked that it's p.q[r].b = 42 and not p.q[r] = 42. So, the extra S keys would (could) be "a", "b", "c". ✔️

srenatus · 2023-08-31T07:24:30Z

docs/content/policy-language.md

+Any term, except the very first, in a rule head's reference can be a variable. These variables can be assigned within the rule, just as for any other partial rule, to dynamically construct a nested collection of objects. 
+
+{{< danger >}}
+General refs in rule heads is an experimental feature, and can be enabled by setting the `OPA_ENABLE_GENERAL_RULE_REFS` environment variable.


I was wondering about the name for a moment, but I think it's OK. We've got another example here, FWIW.

Ah, I'll change this to EXPERIMENTAL_GENERAL_RULE_REFS, to align 👍 .

srenatus · 2023-08-31T07:24:53Z

docs/content/policy-language.md

+import future.keywords
+
+# A partial object rule that converts a list of users to a mapping by "role" and then "id".
+users_by_role[role][id] := user {


Let's throw in an if here and below

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling force-pushed the jf/5685/multi-var-rule-refs branch 2 times, most recently from 8ef1c96 to 9ae279d Compare May 30, 2023 08:42

johanfylling marked this pull request as ready for review May 30, 2023 11:23

johanfylling changed the title ~~WIP: Arbitrary vars in rule refs~~ Arbitrary vars in rule refs May 30, 2023

ashutosh-narkar requested a review from srenatus May 30, 2023 22:20

srenatus reviewed May 31, 2023

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topdown: Adding support for multiple variables in rule refs

525c93d

This is the topdown part of supporting generic refs. Fixes: open-policy-agent#5993 Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling force-pushed the jf/5685/multi-var-rule-refs branch from e2dbd38 to 525c93d Compare June 9, 2023 16:49

johanfylling linked an issue Jun 9, 2023 that may be closed by this pull request

general ref heads: topdown #5993

Closed

Merge branch 'main' into jf/5685/multi-var-rule-refs

5f70376

ashutosh-narkar requested a review from srenatus July 5, 2023 16:26

srenatus reviewed Jul 6, 2023

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johanfylling added 16 commits July 6, 2023 16:57

Updating commented-out tests.

d387cfd

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Fixing yaml test expecting multiple results.

d1dcb03

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Not running yaml test for WASM

2073c3d

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Merge branch 'main' into jf/5685/multi-var-rule-refs

29c2a2e

Moving type merge from typeChecker.checkRule() to `typeTreeNode.Ins…

659ef2a

…ert()` Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Updating type-checker to handle generic rule refs

692770e

Fixes: open-policy-agent#5994 Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Updating tests

9707e66

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Generalizing types.Object.Merge()`

391d469

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Merging sub-objects in types.Object.Merge()

ea52a01

instead of `Or`:ing them Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Removing comment in test

996cdec

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Updating tests

1065755

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Aligning hint-key and entry for general refs on virtual partial eval

67ba943

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Enforcing no-else parser rule on general ref heads

8ffcf1d

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

PE impl

f02441d

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Removing redundant legacy PE eval branch

68f9436

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Fixing issue where PE-produced query contained non-namespaced local vars

bec96d1

Nested object created by general ref didn't maintain ground:ness even though containing vars. Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling added 3 commits August 18, 2023 18:31

Adding PE tests

33ebc2f

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Invoking evalOneRulePostUnify() for any ref with unknowns overlapping…

80620a0

… with dynamic portion of a rule ref Signed-off-by: Johan Fylling <johan.dev@fylling.se>

fmt: Not using rule ref ground prefix if ref has dynamic part

98178fb

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling force-pushed the jf/5685/multi-var-rule-refs branch from 213ac32 to b9ea4d5 Compare August 21, 2023 16:20

Fixing linter warnings

372def8

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling force-pushed the jf/5685/multi-var-rule-refs branch from b9ea4d5 to 372def8 Compare August 21, 2023 16:53

johanfylling added 4 commits August 22, 2023 11:01

Ignoring additional yaml tests not supported by Wasm

9e544c6

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Merge branch 'main' into jf/5685/multi-var-rule-refs

0fa5652

Cleanup

52bb04d

* Adding comments * Removing unused stuff * Rename evalOneDynamicRefRulePreUnify() -> evalOneRulePreUnify() Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Producing cache hint keys containing entire applicable ref for genera…

18702a3

…l ref heads Signed-off-by: Johan Fylling <johan.dev@fylling.se>

srenatus reviewed Aug 24, 2023

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johanfylling added 3 commits August 29, 2023 14:02

Merge branch 'main' into jf/5685/multi-var-rule-refs

d4ac3b0

Conflicts: ast/env.go

Updating type-tree construction

9e46555

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Merge branch 'main' into jf/5685/multi-var-rule-refs

e1c0a23

ashutosh-narkar reviewed Aug 29, 2023

View reviewed changes

johanfylling added 3 commits August 29, 2023 19:59

Removing debug print

2e7121b

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

Merge branch 'main' into jf/5685/multi-var-rule-refs

a98a6ee

Adding docs

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Signed-off-by: Johan Fylling <johan.dev@fylling.se>

srenatus previously approved these changes Aug 31, 2023

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johanfylling added 2 commits August 31, 2023 11:31

Merge branch 'main' into jf/5685/multi-var-rule-refs

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Making changes suggested by @srenatus

ebf1503

Signed-off-by: Johan Fylling <johan.dev@fylling.se>

johanfylling dismissed srenatus’s stale review via ebf1503 August 31, 2023 10:11

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johanfylling merged commit 0431567 into open-policy-agent:main Aug 31, 2023
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Arbitrary vars in rule refs #5913

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	# query: i := ["foo", "bar"][_]; data.test.p.q[i].s = x
	# query: 'i := ["foo", "bar"][_]; data.test.p.q[i].s = x'

Arbitrary vars in rule refs #5913

Arbitrary vars in rule refs #5913

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