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// -
// ========================LICENSE_START=================================
// Copyright (C) 2024: Deutsche Telecom
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========================LICENSE_END===================================
// The opasdk package provides functionalities for integrating with the Open Policy Agent
// (OPA) SDK, including reading configurations and managing a singleton OPA instance.
// This package is designed to ensure efficient, thread-safe initialization and configuration
// of the OPA instance.
package opasdk
import (
"bytes"
"context"
"fmt"
"io"
"os"
"policy-opa-pdp/consts"
"policy-opa-pdp/pkg/log"
"sync"
"github.com/open-policy-agent/opa/sdk"
)
// Define the structs
var (
opaInstance *sdk.OPA //A singleton instance of the OPA object
once sync.Once //A sync.Once variable used to ensure that the OPA instance is initialized only once,
)
// reads JSON configuration from a file and return a jsonReader
func getJSONReader(filePath string, openFunc func(string) (*os.File, error),
readAllFunc func(io.Reader) ([]byte, error)) (*bytes.Reader, error) {
file, err := openFunc(filePath)
if err != nil {
return nil, fmt.Errorf("error opening file: %w", err)
}
defer file.Close()
byteValue, err := readAllFunc(file)
if err != nil {
return nil, fmt.Errorf("error reading config file: %w", err)
}
jsonReader := bytes.NewReader(byteValue)
return jsonReader, nil
}
// Returns a singleton instance of the OPA object. The initialization of the instance is
// thread-safe, and the OPA object is configured using a JSON configuration file.
func GetOPASingletonInstance() (*sdk.OPA, error) {
var err error
once.Do(func() {
var opaErr error
opaInstance, opaErr = sdk.New(context.Background(), sdk.Options{
// Configure your OPA instance here
V1Compatible: true,
})
log.Debugf("Create an instance of OPA Object")
if opaErr != nil {
log.Warnf("Error creating OPA instance: %s", opaErr)
err = opaErr
return
} else {
jsonReader, jsonErr := getJSONReader(consts.OpasdkConfigPath, os.Open, io.ReadAll)
if jsonErr != nil {
log.Warnf("Error getting JSON reader: %s", jsonErr)
err = jsonErr
return
}
log.Debugf("Configure an instance of OPA Object")
opaInstance.Configure(context.Background(), sdk.ConfigOptions{
Config: jsonReader,
})
}
})
return opaInstance, err
}
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