feat: add resourceid package

Forklifted from incubator repo, contains validation for user-settable
IDs and default implementation of system-generated IDs.

go.mod

@@ -4,6 +4,7 @@ go 1.15
 
 require (
 	github.com/golang/protobuf v1.4.3 // indirect
+	github.com/google/uuid v1.1.2
 	google.golang.org/genproto v0.0.0-20201214200347-8c77b98c765d
 	google.golang.org/protobuf v1.25.0
 	gotest.tools/v3 v3.0.3

go.sum

@@ -23,6 +23,8 @@ github.com/google/go-cmp v0.3.1/go.mod h1:8QqcDgzrUqlUb/G2PQTWiueGozuR1884gddMyw
 github.com/google/go-cmp v0.4.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.0 h1:/QaMHBdZ26BB3SSst0Iwl10Epc+xhTquomWX0oZEB6w=
 github.com/google/go-cmp v0.5.0/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/uuid v1.1.2 h1:EVhdT+1Kseyi1/pUmXKaFxYsDNy9RQYkMWRH68J/W7Y=
+github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=

resourceid/systemgenerated.go

@@ -0,0 +1,8 @@
+package resourceid
+
+import "github.com/google/uuid"
+
+// NewSystemGenerated returns a new system-generated resource ID.
+func NewSystemGenerated() string {
+	return uuid.New().String()
+}

resourceid/systemgenerated_test.go

@@ -0,0 +1,15 @@
+package resourceid
+
+import (
+	"regexp"
+	"testing"
+
+	"gotest.tools/v3/assert"
+	"gotest.tools/v3/assert/cmp"
+)
+
+func TestNewSystemGenerated(t *testing.T) {
+	t.Parallel()
+	const uuidV4Regexp = `^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$`
+	assert.Assert(t, cmp.Regexp(regexp.MustCompile(uuidV4Regexp), NewSystemGenerated()))
+}

resourceid/usersettable.go

@@ -0,0 +1,48 @@
+package resourceid
+
+import (
+	"fmt"
+
+	"github.com/google/uuid"
+)
+
+// ValidateUserSettable validates a user-settable resource ID.
+//
+// From https://google.aip.dev/122#resource-id-segments:
+//
+// User-settable resource IDs should conform to RFC-1034,which restricts to letters, numbers, and hyphen, with a 63
+// character maximum. Additionally, user-settable resource IDs should restrict letters to lower-case.
+//
+// User-settable IDs should not be permitted to be a UUID (or any value that syntactically appears to be a UUID).
+//
+// See also: https://google.aip.dev/133#user-specified-ids
+func ValidateUserSettable(id string) error {
+	if len(id) < 4 || 63 < len(id) {
+		return fmt.Errorf("user-settable ID must be between 4 and 63 characters")
+	}
+	if id[0] == '-' {
+		return fmt.Errorf("user-settable ID must not start with a hyphen")
+	}
+	if _, err := uuid.Parse(id); err == nil {
+		return fmt.Errorf("user-settable ID must not be a valid UUIDv4")
+	}
+	for position, character := range id {
+		switch character {
+		case
+			// numbers
+			'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+			// hyphen
+			'-',
+			// lower-case
+			'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
+			'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z':
+		default:
+			return fmt.Errorf(
+				"user-settable ID must only contain lowercase, numbers and hyphens (got: '%c' in position %d)",
+				character,
+				position,
+			)
+		}
+	}
+	return nil
+}

resourceid/usersettable_test.go

@@ -0,0 +1,33 @@
+package resourceid
+
+import (
+	"testing"
+
+	"gotest.tools/v3/assert"
+)
+
+func TestValidateUserSettable(t *testing.T) {
+	t.Parallel()
+	for _, tt := range []struct {
+		id            string
+		errorContains string
+	}{
+		{id: "abcd"},
+		{id: "abcd-efgh-1234"},
+		{id: "abc", errorContains: "must be between 4 and 63 characters"},
+		{id: "-abc", errorContains: "must not start with a hyphen"},
+		{id: "daf1cb3e-f33b-43f1-81cc-e65fda51efa5", errorContains: "must not be a valid UUIDv4"},
+		{id: "abcd/efgh", errorContains: "must only contain lowercase, numbers and hyphens"},
+	} {
+		tt := tt
+		t.Run(tt.id, func(t *testing.T) {
+			t.Parallel()
+			err := ValidateUserSettable(tt.id)
+			if tt.errorContains != "" {
+				assert.ErrorContains(t, err, tt.errorContains)
+			} else {
+				assert.NilError(t, err)
+			}
+		})
+	}
+}