[Metricbeat] support credentials_json in gcp module

CHANGELOG-developer.next.asciidoc

@@ -129,6 +129,7 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - Introduce `libbeat/beat.Beat.OutputConfigReloader` {pull}28048[28048]
 - Update Go version to 1.17.1. {pull}27543[27543]
 - Whitelist `GCP_*` environment variables in dev tools {pull}28364[28364]
+- Add support for `credentials_json` in `gcp` module, all metricsets {pull}29584[29584]
 
 ==== Deprecated
 

x-pack/metricbeat/module/gcp/billing/billing.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
+	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -49,14 +50,19 @@ type MetricSet struct {
 type config struct {
 	Period              time.Duration `config:"period" validate:"required"`
 	ProjectID           string        `config:"project_id" validate:"required"`
-	CredentialsFilePath string        `config:"credentials_file_path" validate:"required"`
+	CredentialsFilePath string        `config:"credentials_file_path"`
+	CredentialsJSON     string        `config:"credentials_json"`
 	DatasetID           string        `config:"dataset_id" validate:"required"`
 	TablePattern        string        `config:"table_pattern"`
 	CostType            string        `config:"cost_type"`
 }
 
 // Validate checks for deprecated config options
 func (c config) Validate() error {
+	if c.CredentialsFilePath == "" && c.CredentialsJSON == "" {
+		return errors.New("no credentials_file_path or credentials_json specified")
+	}
+
 	if c.CostType != "" {
 		// cost_type can only be regular, tax, adjustment, or rounding error
 		costTypes := []string{"regular", "tax", "adjustment", "rounding error"}
@@ -106,7 +112,17 @@ func (m *MetricSet) Fetch(ctx context.Context, reporter mb.ReporterV2) (err erro
 	// find current month
 	month := getCurrentMonth()
 
-	opt := []option.ClientOption{option.WithCredentialsFile(m.config.CredentialsFilePath)}
+	var opt []option.ClientOption
+	if m.config.CredentialsFilePath != "" && m.config.CredentialsJSON != "" {
+		return errors.New("both credentials_file_path and credentials_json specified, you must use only one of them")
+	} else if m.config.CredentialsFilePath != "" {
+		opt = []option.ClientOption{option.WithCredentialsFile(m.config.CredentialsFilePath)}
+	} else if m.config.CredentialsJSON != "" {
+		opt = []option.ClientOption{option.WithCredentialsJSON([]byte(m.config.CredentialsJSON))}
+	} else {
+		return errors.New("no credentials_file_path or credentials_json specified")
+	}
+
 	client, err := bigquery.NewClient(ctx, m.config.ProjectID, opt...)
 	if err != nil {
 		return fmt.Errorf("gerror creating bigquery client: %w", err)
@@ -286,7 +302,7 @@ func getCurrentDate() string {
 }
 
 func generateEventID(currentDate string, rowItems []bigquery.Value) string {
-	// create eventID using hash of current_date + invoice_month + project_id + cost_type
+	// create eventID using hash of current_date + invoice.month + project.id + project.name
 	// This will prevent more than one billing metric getting collected in the same day.
 	eventID := currentDate + rowItems[0].(string) + rowItems[1].(string) + rowItems[2].(string)
 	h := sha256.New()

x-pack/metricbeat/module/gcp/metrics/metricset.go

@@ -104,6 +104,7 @@ type config struct {
 	ProjectID           string `config:"project_id" validate:"required"`
 	ExcludeLabels       bool   `config:"exclude_labels"`
 	CredentialsFilePath string `config:"credentials_file_path"`
+	CredentialsJSON     string `config:"credentials_json"`
 
 	opt    []option.ClientOption
 	period *duration.Duration
@@ -129,7 +130,17 @@ func New(base mb.BaseMetricSet) (mb.MetricSet, error) {
 	}
 
 	m.MetricsConfig = metricsConfigs.Metrics
-	m.config.opt = []option.ClientOption{option.WithCredentialsFile(m.config.CredentialsFilePath)}
+
+	if m.config.CredentialsFilePath != "" && m.config.CredentialsJSON != "" {
+		return m, errors.New("both credentials_file_path and credentials_json specified, you must use only one of them")
+	} else if m.config.CredentialsFilePath != "" {
+		m.config.opt = []option.ClientOption{option.WithCredentialsFile(m.config.CredentialsFilePath)}
+	} else if m.config.CredentialsJSON != "" {
+		m.config.opt = []option.ClientOption{option.WithCredentialsJSON([]byte(m.config.CredentialsJSON))}
+	} else {
+		return m, errors.New("no credentials_file_path or credentials_json specified")
+	}
+
 	m.config.period = &duration.Duration{
 		Seconds: int64(m.Module().Config().Period.Seconds()),
 	}