accumulator/metadata.go

// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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.

package accumulator

import (
	"bytes"
	"compress/gzip"
	"compress/zlib"
	"fmt"
	"io"
)

// ProcessMetadata return a byte array containing the Metadata marshaled in JSON
// In case we want to update the Metadata values, usage of https://github.com/tidwall/sjson is advised
func ProcessMetadata(data APMData) ([]byte, error) {
	uncompressedData, err := GetUncompressedBytes(data.Data, data.ContentEncoding)
	if err != nil {
		return nil, fmt.Errorf("error uncompressing agent data for metadata extraction: %w", err)
	}

	before, _, _ := bytes.Cut(uncompressedData, []byte("\n"))
	return before, nil
}

func GetUncompressedBytes(rawBytes []byte, encodingType string) ([]byte, error) {
	switch encodingType {
	case "deflate":
		reader := bytes.NewReader(rawBytes)
		zlibreader, err := zlib.NewReader(reader)
		if err != nil {
			return nil, fmt.Errorf("could not create zlib.NewReader: %w", err)
		}
		defer zlibreader.Close()
		bodyBytes, err := io.ReadAll(zlibreader)
		if err != nil {
			return nil, fmt.Errorf("could not read from zlib reader using io.ReadAll: %w", err)
		}
		return bodyBytes, nil
	case "gzip":
		reader := bytes.NewReader(rawBytes)
		gzipreader, err := gzip.NewReader(reader)
		if err != nil {
			return nil, fmt.Errorf("could not create gzip.NewReader: %w", err)
		}
		defer gzipreader.Close()
		bodyBytes, err := io.ReadAll(gzipreader)
		if err != nil {
			return nil, fmt.Errorf("could not read from gzip reader using io.ReadAll: %w", err)
		}
		return bodyBytes, nil
	default:
		return rawBytes, nil
	}
}