An example code to send metrics to New Relic

NewRelicMetricsSender.cs

using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;

Console.WriteLine("Start sending metrics...");

var key = Environment.GetEnvironmentVariable("Api-Key");

var client = new HttpClient();
client.DefaultRequestHeaders.Add("Api-Key", key);

var interval = TimeSpan.FromSeconds(60);
while (true)
{
    var now = DateTimeOffset.UtcNow;
    MetricsContent[] root;
    var attributesA = new Dictionary<string, object>
    {
        { "host", "HostA" }
    };
    var attributesB = new Dictionary<string, object>
    {
        { "host", "HostB" }
    };
    if (now.Minute % 60 == 0)
    {
        root = new[]
            {
            new MetricsContent{
                Metrics = new[]
                {
                    new Metric
                    {
                        Name = "test.metrics1",
                        Type = "gauge",
                        Value = 10,
                        Timestamp = now.ToUnixTimeMilliseconds(),
                        Intervalms = (int)interval.TotalMilliseconds,
                        Attributes = attributesA
                    },
                    new Metric
                    {
                        Name = "test.metrics2",
                        Type = "gauge",
                        Value = 10,
                        Timestamp = now.ToUnixTimeMilliseconds(),
                        Intervalms = (int)interval.TotalMilliseconds,
                        Attributes = attributesB
                    }
                }
            }
        };
    }
    else
    {
        root = new[]
            {
            new MetricsContent{
                Metrics = new[]
                {
                    new Metric
                    {
                        Name = "test.metrics1",
                        Type = "gauge",
                        Value = 0,
                        Timestamp = now.ToUnixTimeMilliseconds(),
                        Intervalms = (int)interval.TotalMilliseconds,
                        Attributes = attributesA
                    }
                }
            }
        };
    }
    var options = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
    Console.WriteLine(JsonSerializer.Serialize(root, options));
    var res = await client.PostAsync("https://metric-api.newrelic.com/metric/v1", JsonContent.Create(root, options:options));
    Console.WriteLine(res.StatusCode);
    Console.WriteLine(await res.Content.ReadAsStringAsync());
    await Task.Delay(interval);
}

public class MetricsContent
{
    public Metric[]? Metrics { get; set; }
}

public class Metric
{
    public string? Name { get; set; }
    public string? Type { get; set; }
    public object? Value { get; set; }
    public long Timestamp { get; set; }
    [JsonPropertyName("interval.ms")]
    public int Intervalms { get; set; }
    public Dictionary<string, object> Attributes { get; set; } = new Dictionary<string, object>();
}