Create user-defined metrics with the API

        public static object WriteTimeSeriesData(string projectId)
        {
            // Create client.
            MetricServiceClient metricServiceClient = MetricServiceClient.Create();
            // Initialize request argument(s).
            ProjectName name = new ProjectName(projectId);
            // Prepare a data point. 
            Point dataPoint = new Point();
            TypedValue salesTotal = new TypedValue();
            salesTotal.DoubleValue = 123.45;
            dataPoint.Value = salesTotal;
            Timestamp timeStamp = new Timestamp();
            timeStamp.Seconds = (long)(DateTime.UtcNow - s_unixEpoch).TotalSeconds;
            TimeInterval interval = new TimeInterval();
            interval.EndTime = timeStamp;
            dataPoint.Interval = interval;

            // Prepare custom metric.
            Metric metric = new Metric();
            metric.Type = "custom.googleapis.com/stores/daily_sales";
            metric.Labels.Add("store_id", "Pittsburgh");

            // Prepare monitored resource.
            MonitoredResource resource = new MonitoredResource();
            resource.Type = "global";
            resource.Labels.Add("project_id", projectId);

            // Create a new time series using inputs.
            TimeSeries timeSeriesData = new TimeSeries();
            timeSeriesData.Metric = metric;
            timeSeriesData.Resource = resource;
            timeSeriesData.Points.Add(dataPoint);

            // Add newly created time series to list of time series to be written.
            IEnumerable<TimeSeries> timeSeries = new List<TimeSeries> { timeSeriesData };
            // Write time series data.
            metricServiceClient.CreateTimeSeries(name, timeSeries);
            Console.WriteLine("Done writing time series data:");
            Console.WriteLine(JObject.Parse($"{timeSeriesData}").ToString());
            return 0;
        }

// writeTimeSeriesValue writes a value for the custom metric created
func writeTimeSeriesValue(projectID, metricType string) error {
	ctx := context.Background()
	c, err := monitoring.NewMetricClient(ctx)
	if err != nil {
		return err
	}
	defer c.Close()
	now := &timestamp.Timestamp{
		Seconds: time.Now().Unix(),
	}
	req := &monitoringpb.CreateTimeSeriesRequest{
		Name: "projects/" + projectID,
		TimeSeries: []*monitoringpb.TimeSeries{{
			Metric: &metricpb.Metric{
				Type: metricType,
				Labels: map[string]string{
					"environment": "STAGING",
				},
			},
			Resource: &monitoredres.MonitoredResource{
				Type: "gce_instance",
				Labels: map[string]string{
					"instance_id": "test-instance",
					"zone":        "us-central1-f",
				},
			},
			Points: []*monitoringpb.Point{{
				Interval: &monitoringpb.TimeInterval{
					StartTime: now,
					EndTime:   now,
				},
				Value: &monitoringpb.TypedValue{
					Value: &monitoringpb.TypedValue_Int64Value{
						Int64Value: rand.Int63n(10),
					},
				},
			}},
		}},
	}
	log.Printf("writeTimeseriesRequest: %+v\n", req)

	err = c.CreateTimeSeries(ctx, req)
	if err != nil {
		return fmt.Errorf("could not write time series value, %w ", err)
	}
	return nil
}

String projectId = System.getProperty("projectId");

// Prepares an individual data point
TimeInterval interval =
    TimeInterval.newBuilder()
        .setEndTime(Timestamps.fromMillis(System.currentTimeMillis()))
        .build();
TypedValue value = TypedValue.newBuilder().setDoubleValue(123.45).build();
Point point = Point.newBuilder().setInterval(interval).setValue(value).build();

List<Point> pointList = new ArrayList<>();
pointList.add(point);

ProjectName name = ProjectName.of(projectId);

// Prepares the metric descriptor
Map<String, String> metricLabels = new HashMap<>();
Metric metric =
    Metric.newBuilder()
        .setType("custom.googleapis.com/my_metric")
        .putAllLabels(metricLabels)
        .build();

// Prepares the monitored resource descriptor
Map<String, String> resourceLabels = new HashMap<>();
resourceLabels.put("instance_id", "1234567890123456789");
resourceLabels.put("zone", "us-central1-f");

MonitoredResource resource =
    MonitoredResource.newBuilder().setType("gce_instance").putAllLabels(resourceLabels).build();

// Prepares the time series request
TimeSeries timeSeries =
    TimeSeries.newBuilder()
        .setMetric(metric)
        .setResource(resource)
        .addAllPoints(pointList)
        .build();

List<TimeSeries> timeSeriesList = new ArrayList<>();
timeSeriesList.add(timeSeries);

CreateTimeSeriesRequest request =
    CreateTimeSeriesRequest.newBuilder()
        .setName(name.toString())
        .addAllTimeSeries(timeSeriesList)
        .build();

// Writes time series data
try (final MetricServiceClient client = MetricServiceClient.create();) {
  client.createTimeSeries(request);
}
System.out.println("Done writing time series value.");

// Imports the Google Cloud client library
const monitoring = require('@google-cloud/monitoring');

// Creates a client
const client = new monitoring.MetricServiceClient();

async function writeTimeSeriesData() {
  /**
   * TODO(developer): Uncomment and edit the following lines of code.
   */
  // const projectId = 'YOUR_PROJECT_ID';

  const dataPoint = {
    interval: {
      endTime: {
        seconds: Date.now() / 1000,
      },
    },
    value: {
      doubleValue: 123.45,
    },
  };

  const timeSeriesData = {
    metric: {
      type: 'custom.googleapis.com/stores/daily_sales',
      labels: {
        store_id: 'Pittsburgh',
      },
    },
    resource: {
      type: 'global',
      labels: {
        project_id: projectId,
      },
    },
    points: [dataPoint],
  };

  const request = {
    name: client.projectPath(projectId),
    timeSeries: [timeSeriesData],
  };

  // Writes time series data
  const result = await client.createTimeSeries(request);
  console.log('Done writing time series data.', result);
}
writeTimeSeriesData();

use Google\Api\Metric;
use Google\Api\MonitoredResource;
use Google\Cloud\Monitoring\V3\Client\MetricServiceClient;
use Google\Cloud\Monitoring\V3\CreateTimeSeriesRequest;
use Google\Cloud\Monitoring\V3\Point;
use Google\Cloud\Monitoring\V3\TimeInterval;
use Google\Cloud\Monitoring\V3\TimeSeries;
use Google\Cloud\Monitoring\V3\TypedValue;
use Google\Protobuf\Timestamp;

/**
 * Example:
 * ```
 * write_timeseries($projectId);
 * ```
 *
 * @param string $projectId Your project ID
 */
function write_timeseries($projectId)
{
    $metrics = new MetricServiceClient([
        'projectId' => $projectId,
    ]);

    $projectName = 'projects/' . $projectId;

    $endTime = new Timestamp();
    $endTime->setSeconds(time());
    $interval = new TimeInterval();
    $interval->setEndTime($endTime);

    $value = new TypedValue();
    $value->setDoubleValue(123.45);

    $point = new Point();
    $point->setValue($value);
    $point->setInterval($interval);
    $points = [$point];

    $metric = new Metric();
    $metric->setType('custom.googleapis.com/stores/daily_sales');
    $labels = ['store_id' => 'Pittsburg'];
    $metric->setLabels($labels);

    $resource = new MonitoredResource();
    $resource->setType('global');
    $labels = ['project_id' => $projectId];
    $resource->setLabels($labels);

    $timeSeries = new TimeSeries();
    $timeSeries->setMetric($metric);
    $timeSeries->setResource($resource);
    $timeSeries->setPoints($points);
    $createTimeSeriesRequest = (new CreateTimeSeriesRequest())
        ->setName($projectName)
        ->setTimeSeries([$timeSeries]);

    $metrics->createTimeSeries($createTimeSeriesRequest);

    printf('Done writing time series data.' . PHP_EOL);
}

from google.cloud import monitoring_v3

client = monitoring_v3.MetricServiceClient()
project_name = f"projects/{project_id}"

series = monitoring_v3.TimeSeries()
series.metric.type = "custom.googleapis.com/my_metric" + str(uuid.uuid4())
series.resource.type = "gce_instance"
series.resource.labels["instance_id"] = "1234567890123456789"
series.resource.labels["zone"] = "us-central1-c"
series.metric.labels["TestLabel"] = "My Label Data"
now = time.time()
seconds = int(now)
nanos = int((now - seconds) * 10**9)
interval = monitoring_v3.TimeInterval(
    {"end_time": {"seconds": seconds, "nanos": nanos}}
)
point = monitoring_v3.Point({"interval": interval, "value": {"double_value": 3.14}})
series.points = [point]
client.create_time_series(name=project_name, time_series=[series])

gem "google-cloud-monitoring"
require "google/cloud/monitoring"

# Your Google Cloud Platform project ID
# project_id = "YOUR_PROJECT_ID"

# Example metric type
# metric_type = "custom.googleapis.com/my_metric"

client = Google::Cloud::Monitoring.metric_service
project_name = client.project_path project: project_id

series = Google::Cloud::Monitoring::V3::TimeSeries.new
series.metric = Google::Api::Metric.new type: metric_type

resource = Google::Api::MonitoredResource.new type: "global"
resource.labels["project_id"] = project_id
series.resource = resource

point = Google::Cloud::Monitoring::V3::Point.new
point.value = Google::Cloud::Monitoring::V3::TypedValue.new double_value: 3.14
now = Time.now
end_time = Google::Protobuf::Timestamp.new seconds: now.to_i, nanos: now.nsec
point.interval = Google::Cloud::Monitoring::V3::TimeInterval.new end_time: end_time
series.points << point

client.create_time_series name: project_name, time_series: [series]
p "Time series created."

public static object DeleteMetric(string projectId, string metricType)
{
    // Create client.
    MetricServiceClient metricServiceClient = MetricServiceClient.Create();
    // Initialize request argument(s).
    MetricDescriptorName name = new MetricDescriptorName(projectId, metricType);
    // Make the request.
    metricServiceClient.DeleteMetricDescriptor(name);
    Console.WriteLine($"Done deleting metric descriptor: {name}");
    return 0;
}

import (
	"context"
	"fmt"
	"io"

	monitoring "cloud.google.com/go/monitoring/apiv3"
	"cloud.google.com/go/monitoring/apiv3/v2/monitoringpb"
)

// deleteMetric deletes the given metric. name should be of the form
// "projects/PROJECT_ID/metricDescriptors/METRIC_TYPE".
func deleteMetric(w io.Writer, name string) error {
	ctx := context.Background()
	c, err := monitoring.NewMetricClient(ctx)
	if err != nil {
		return err
	}
	defer c.Close()
	req := &monitoringpb.DeleteMetricDescriptorRequest{
		Name: name,
	}

	if err := c.DeleteMetricDescriptor(ctx, req); err != nil {
		return fmt.Errorf("could not delete metric: %w", err)
	}
	fmt.Fprintf(w, "Deleted metric: %q\n", name)
	return nil
}

final String projectId = System.getProperty("projectId");
try (final MetricServiceClient client = MetricServiceClient.create();) {
  MetricDescriptorName metricName = MetricDescriptorName.of(projectId, type);
  client.deleteMetricDescriptor(metricName);
  System.out.println("Deleted descriptor " + type);
}

// Imports the Google Cloud client library
const monitoring = require('@google-cloud/monitoring');

// Creates a client
const client = new monitoring.MetricServiceClient();

async function deleteMetricDescriptor() {
  /**
   * TODO(developer): Uncomment and edit the following lines of code.
   */
  // const projectId = 'YOUR_PROJECT_ID';
  // const metricId = 'custom.googleapis.com/stores/daily_sales';

  const request = {
    name: client.projectMetricDescriptorPath(projectId, metricId),
  };

  // Deletes a metric descriptor
  const [result] = await client.deleteMetricDescriptor(request);
  console.log(`Deleted ${metricId}`, result);
}
deleteMetricDescriptor();

use Google\Cloud\Monitoring\V3\Client\MetricServiceClient;
use Google\Cloud\Monitoring\V3\DeleteMetricDescriptorRequest;

/**
 * Example:
 * ```
 * delete_metric($projectId, $databaseId);
 * ```
 *
 * @param string $projectId Your project ID
 * @param string $metricId  The ID of the Metric Descriptor to delete
 */
function delete_metric($projectId, $metricId)
{
    $metrics = new MetricServiceClient([
        'projectId' => $projectId,
    ]);

    $metricPath = $metrics->metricDescriptorName($projectId, $metricId);
    $deleteMetricDescriptorRequest = (new DeleteMetricDescriptorRequest())
        ->setName($metricPath);
    $metrics->deleteMetricDescriptor($deleteMetricDescriptorRequest);

    printf('Deleted a metric: ' . $metricPath . PHP_EOL);
}

from google.cloud import monitoring_v3

client = monitoring_v3.MetricServiceClient()
client.delete_metric_descriptor(name=descriptor_name)
print("Deleted metric descriptor {}.".format(descriptor_name))

gem "google-cloud-monitoring"
require "google/cloud/monitoring"

# Your Google Cloud Platform project ID
# project_id = "YOUR_PROJECT_ID"

# Example metric type
# metric_type = "custom.googleapis.com/my_metric"

client = Google::Cloud::Monitoring.metric_service
metric_name = client.metric_descriptor_path project:           project_id,
                                            metric_descriptor: metric_type

client.delete_metric_descriptor name: metric_name
p "Deleted metric descriptor #{metric_name}."