Revert "Fix some leaks in opa policies (networkservicemesh#1624)"

This reverts commit c2a3414.

pkg/tools/opa/policy.go

@@ -1,6 +1,6 @@
 // Copyright (c) 2020-2022 Doc.ai and/or its affiliates.
 //
-// Copyright (c) 2023-2024 Cisco and/or its affiliates.
+// Copyright (c) 2023 Cisco and/or its affiliates.
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -20,10 +20,10 @@ package opa
 
 import (
 	"context"
-	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"github.com/open-policy-agent/opa/rego"
 	"github.com/pkg/errors"
@@ -77,12 +77,15 @@ func WithNamedPolicyFromSource(name, source, query string, checkQuery CheckQuery
 
 // AuthorizationPolicy checks that passed tokens are valid
 type AuthorizationPolicy struct {
+	initErr        error
 	name           string
 	policyFilePath string
 	policySource   string
 	pkg            string
 	query          string
+	evalQuery      *rego.PreparedEvalQuery
 	checker        CheckAccessFunc
+	once           sync.Once
 }
 
 // Name returns AuthorizationPolicy name
@@ -96,11 +99,10 @@ func (d *AuthorizationPolicy) Check(ctx context.Context, model interface{}) erro
 	if err != nil {
 		return err
 	}
-	evalQuery, intErr := d.init()
-	if intErr != nil {
+	if intErr := d.init(); intErr != nil {
 		return intErr
 	}
-	rs, err := evalQuery.Eval(ctx, rego.EvalInput(input))
+	rs, err := d.evalQuery.Eval(ctx, rego.EvalInput(input))
 	if err != nil {
 		return status.Error(codes.Internal, err.Error())
 	}
@@ -114,23 +116,33 @@ func (d *AuthorizationPolicy) Check(ctx context.Context, model interface{}) erro
 	return nil
 }
 
-func (d *AuthorizationPolicy) init() (*rego.PreparedEvalQuery, error) {
-	if d.query == "" {
-		d.query = strings.TrimSuffix(filepath.Base(d.policyFilePath), filepath.Ext(d.policyFilePath))
-	}
-	if err := d.loadSource(); err != nil {
-		return nil, err
-	}
-	if err := d.checkModule(); err != nil {
-		return nil, err
+func (d *AuthorizationPolicy) init() error {
+	d.once.Do(func() {
+		if d.query == "" {
+			d.query = strings.TrimSuffix(filepath.Base(d.policyFilePath), filepath.Ext(d.policyFilePath))
+		}
+		if d.initErr = d.loadSource(); d.initErr != nil {
+			return
+		}
+		if d.initErr = d.checkModule(); d.initErr != nil {
+			return
+		}
+		var r rego.PreparedEvalQuery
+		r, d.initErr = rego.New(
+			rego.Query(strings.Join([]string{"data", d.pkg, d.query}, ".")),
+			rego.Module(d.pkg, d.policySource)).PrepareForEval(context.Background())
+		if d.initErr != nil {
+			return
+		}
+		d.evalQuery = &r
+	})
+	if d.initErr != nil {
+		return d.initErr
 	}
-	r, err := rego.New(
-		rego.Query(strings.Join([]string{"data", d.pkg, d.query}, ".")),
-		rego.Module(d.pkg, d.policySource)).PrepareForEval(context.Background())
-	if err != nil {
-		return nil, errors.Wrap(err, fmt.Sprintf("policy %v is not compiled", d.policySource))
+	if d.evalQuery == nil {
+		return errors.Errorf("policy %v is not compiled", d.policySource)
 	}
-	return &r, nil
+	return nil
 }
 
 func (d *AuthorizationPolicy) loadSource() error {