feat(constraints): add compound constraints and olm.constraint value …

…parser (#203)

* feat(constraints): add compound constraints and olm.constraint value parser

Signed-off-by: Eric Stroczynski <ericstroczynski@gmail.com>

* renaming and add yaml tags

Signed-off-by: Eric Stroczynski <ericstroczynski@gmail.com>

pkg/constraints/cel.go

@@ -16,17 +16,6 @@ import (
 // PropertiesKey is the key for bundle properties map (input data for CEL evaluation)
 const PropertiesKey = "properties"
 
-// Constraint is a struct representing the new generic constraint type
-type Constraint struct {
-	// Constraint message that surfaces in resolution
-	// This field is optional
-	Message string `json:"message" yaml:"message"`
-
-	// The cel struct that contraints CEL expression
-	// This field is required
-	Cel *Cel `json:"cel" yaml:"cel"`
-}
-
 // Cel is a struct representing CEL expression information
 type Cel struct {
 	// The CEL expression

pkg/constraints/constraint.go

@@ -0,0 +1,86 @@
+package constraints
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+)
+
+// OLMConstraintType is the schema "type" key for all constraints known to OLM
+// (except for legacy types).
+const OLMConstraintType = "olm.constraint"
+
+// Constraint holds parsed, potentially nested dependency constraints.
+type Constraint struct {
+	// Constraint message that surfaces in resolution
+	// This field is optional
+	Message string `json:"message,omitempty" yaml:"message,omitempty"`
+
+	// The cel struct that contraints CEL expression
+	Cel *Cel `json:"cel,omitempty" yaml:"cel,omitempty"`
+
+	// Package defines a constraint for a package within a version range.
+	Package *PackageConstraint `json:"package,omitempty" yaml:"package,omitempty"`
+
+	// GVK defines a constraint for a GVK.
+	GVK *GVKConstraint `json:"gvk,omitempty" yaml:"gvk,omitempty"`
+
+	// All, Any, and None are compound constraints. See this enhancement for details:
+	// https://github.com/operator-framework/enhancements/blob/master/enhancements/compound-bundle-constraints.md
+	All *CompoundConstraint `json:"all,omitempty" yaml:"all,omitempty"`
+	Any *CompoundConstraint `json:"any,omitempty" yaml:"any,omitempty"`
+	// A note on None: this constraint is not particularly useful by itself.
+	// It should be used within an All constraint alongside some other constraint type
+	// since saying "none of these GVKs/packages/etc." without an alternative doesn't make sense.
+	None *CompoundConstraint `json:"none,omitempty" yaml:"none,omitempty"`
+}
+
+// CompoundConstraint holds a list of potentially nested constraints
+// over which a boolean operation is applied.
+type CompoundConstraint struct {
+	Constraints []Constraint `json:"constraints" yaml:"constraints"`
+}
+
+// GVKConstraint defines a GVK constraint.
+type GVKConstraint struct {
+	Group   string `json:"group" yaml:"group"`
+	Kind    string `json:"kind" yaml:"kind"`
+	Version string `json:"version" yaml:"version"`
+}
+
+// PackageConstraint defines a package constraint.
+type PackageConstraint struct {
+	// PackageName is the name of the package.
+	PackageName string `json:"packageName" yaml:"packageName"`
+	// VersionRange required for the package.
+	VersionRange string `json:"versionRange" yaml:"versionRange"`
+}
+
+// maxConstraintSize defines the maximum raw size in bytes of an olm.constraint.
+// 64Kb seems reasonable, since this number allows for long description strings
+// and either few deep nestings or shallow nestings and long constraints lists,
+// but not both.
+// QUESTION: make this configurable?
+const maxConstraintSize = 2 << 16
+
+// ErrMaxConstraintSizeExceeded is returned when a constraint's size > maxConstraintSize.
+var ErrMaxConstraintSizeExceeded = fmt.Errorf("olm.constraint value is greater than max constraint size %d bytes", maxConstraintSize)
+
+// Parse parses an olm.constraint property's value recursively into a Constraint.
+// Unknown value schemas result in an error. Constraints that exceed the number of bytes
+// defined by maxConstraintSize result results in an error.
+func Parse(v json.RawMessage) (c Constraint, err error) {
+	// There is no way to explicitly limit nesting depth.
+	// From https://github.com/golang/go/issues/31789#issuecomment-538134396,
+	// the recommended approach is to error out if raw input size
+	// is greater than some threshold.
+	if len(v) > maxConstraintSize {
+		return c, ErrMaxConstraintSizeExceeded
+	}
+
+	d := json.NewDecoder(bytes.NewBuffer(v))
+	d.DisallowUnknownFields()
+	err = d.Decode(&c)
+
+	return
+}

pkg/constraints/constraint_test.go

@@ -0,0 +1,274 @@
+package constraints
+
+import (
+	"encoding/json"
+	"fmt"
+	"math/rand"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestParse(t *testing.T) {
+	type spec struct {
+		name          string
+		input         json.RawMessage
+		expConstraint Constraint
+		expError      string
+	}
+
+	specs := []spec{
+		{
+			name:  "Valid/BasicGVK",
+			input: json.RawMessage(inputBasicGVK),
+			expConstraint: Constraint{
+				Message: "blah",
+				GVK:     &GVKConstraint{Group: "example.com", Version: "v1", Kind: "Foo"},
+			},
+		},
+		{
+			name:  "Valid/BasicPackage",
+			input: json.RawMessage(inputBasicPackage),
+			expConstraint: Constraint{
+				Message: "blah",
+				Package: &PackageConstraint{PackageName: "foo", VersionRange: ">=1.0.0"},
+			},
+		},
+		{
+			name:  "Valid/BasicAll",
+			input: json.RawMessage(fmt.Sprintf(inputBasicCompoundTmpl, "all")),
+			expConstraint: Constraint{
+				Message: "blah",
+				All: &CompoundConstraint{
+					Constraints: []Constraint{
+						{
+							Message: "blah blah",
+							Package: &PackageConstraint{PackageName: "fuz", VersionRange: ">=1.0.0"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:  "Valid/BasicAny",
+			input: json.RawMessage(fmt.Sprintf(inputBasicCompoundTmpl, "any")),
+			expConstraint: Constraint{
+				Message: "blah",
+				Any: &CompoundConstraint{
+					Constraints: []Constraint{
+						{
+							Message: "blah blah",
+							Package: &PackageConstraint{PackageName: "fuz", VersionRange: ">=1.0.0"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:  "Valid/BasicNone",
+			input: json.RawMessage(fmt.Sprintf(inputBasicCompoundTmpl, "none")),
+			expConstraint: Constraint{
+				Message: "blah",
+				None: &CompoundConstraint{
+					Constraints: []Constraint{
+						{
+							Message: "blah blah",
+							Package: &PackageConstraint{PackageName: "fuz", VersionRange: ">=1.0.0"},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:  "Valid/Complex",
+			input: json.RawMessage(inputComplex),
+			expConstraint: Constraint{
+				Message: "blah",
+				All: &CompoundConstraint{
+					Constraints: []Constraint{
+						{Package: &PackageConstraint{PackageName: "fuz", VersionRange: ">=1.0.0"}},
+						{GVK: &GVKConstraint{Group: "fals.example.com", Kind: "Fal", Version: "v1"}},
+						{
+							Message: "foo and buf must be stable versions",
+							All: &CompoundConstraint{
+								Constraints: []Constraint{
+									{Package: &PackageConstraint{PackageName: "foo", VersionRange: ">=1.0.0"}},
+									{Package: &PackageConstraint{PackageName: "buf", VersionRange: ">=1.0.0"}},
+									{GVK: &GVKConstraint{Group: "foos.example.com", Kind: "Foo", Version: "v1"}},
+								},
+							},
+						},
+						{
+							Message: "blah blah",
+							Any: &CompoundConstraint{
+								Constraints: []Constraint{
+									{GVK: &GVKConstraint{Group: "foos.example.com", Kind: "Foo", Version: "v1beta1"}},
+									{GVK: &GVKConstraint{Group: "foos.example.com", Kind: "Foo", Version: "v1beta2"}},
+									{GVK: &GVKConstraint{Group: "foos.example.com", Kind: "Foo", Version: "v1"}},
+								},
+							},
+						},
+						{
+							None: &CompoundConstraint{
+								Constraints: []Constraint{
+									{GVK: &GVKConstraint{Group: "bazs.example.com", Kind: "Baz", Version: "v1alpha1"}},
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "Invalid/TooLarge",
+			input: func(t *testing.T) json.RawMessage {
+				p := make([]byte, maxConstraintSize+1)
+				_, err := rand.Read(p)
+				require.NoError(t, err)
+				return json.RawMessage(p)
+			}(t),
+			expError: ErrMaxConstraintSizeExceeded.Error(),
+		},
+		{
+			name: "Invalid/UnknownField",
+			input: json.RawMessage(
+				`{"message": "something", "arbitrary": {"key": "value"}}`,
+			),
+			expError: `json: unknown field "arbitrary"`,
+		},
+	}
+
+	for _, s := range specs {
+		t.Run(s.name, func(t *testing.T) {
+			constraint, err := Parse(s.input)
+			if s.expError == "" {
+				require.NoError(t, err)
+				require.Equal(t, s.expConstraint, constraint)
+			} else {
+				require.EqualError(t, err, s.expError)
+			}
+		})
+	}
+}
+
+const (
+	inputBasicGVK = `{
+		"message": "blah",
+		"gvk": {
+			"group": "example.com",
+			"version": "v1",
+			"kind": "Foo"
+		}
+	}`
+
+	inputBasicPackage = `{
+		"message": "blah",
+		"package": {
+			"packageName": "foo",
+			"versionRange": ">=1.0.0"
+		}
+	}`
+
+	inputBasicCompoundTmpl = `{
+"message": "blah",
+"%s": {
+	"constraints": [
+		{
+			"message": "blah blah",
+			"package": {
+				"packageName": "fuz",
+				"versionRange": ">=1.0.0"
+			}
+		}
+	]
+}}
+`
+
+	inputComplex = `{
+"message": "blah",
+"all": {
+	"constraints": [
+		{
+			"package": {
+				"packageName": "fuz",
+				"versionRange": ">=1.0.0"
+			}
+		},
+		{
+			"gvk": {
+				"group": "fals.example.com",
+				"version": "v1",
+				"kind": "Fal"
+			}
+		},
+		{
+			"message": "foo and buf must be stable versions",
+			"all": {
+				"constraints": [
+					{
+						"package": {
+							"packageName": "foo",
+							"versionRange": ">=1.0.0"
+						}
+					},
+					{
+						"package": {
+							"packageName": "buf",
+							"versionRange": ">=1.0.0"
+						}
+					},
+					{
+						"gvk": {
+							"group": "foos.example.com",
+							"version": "v1",
+							"kind": "Foo"
+						}
+					}
+				]
+			}
+		},
+		{
+			"message": "blah blah",
+			"any": {
+				"constraints": [
+					{
+						"gvk": {
+							"group": "foos.example.com",
+							"version": "v1beta1",
+							"kind": "Foo"
+						}
+					},
+					{
+						"gvk": {
+							"group": "foos.example.com",
+							"version": "v1beta2",
+							"kind": "Foo"
+						}
+					},
+					{
+						"gvk": {
+							"group": "foos.example.com",
+							"version": "v1",
+							"kind": "Foo"
+						}
+					}
+				]
+			}
+		},
+		{
+			"none": {
+				"constraints": [
+					{
+						"gvk": {
+							"group": "bazs.example.com",
+							"version": "v1alpha1",
+							"kind": "Baz"
+						}
+					}
+				]
+			}
+		}
+	]
+}}
+`
+)