private async void RequestHandler(object sender, HttpListenerRequestEventArgs context)
{
try
{
if (context.Request.HttpMethod == HttpMethods.Get)
{
context.Response.StatusCode = 200;
context.Response.Headers.Add("Content-Type", "text/plain; version=0.0.4");
await metrics.Expose(context.Response.OutputStream, ExposeOptions.Default);
}
else
{
context.Response.NotFound();
}
context.Response.Close();
}
catch (Exception ex)
{
try
{
errorHandler?.Invoke(new PrometheusServerException("Error while handling HTTP request", ex));
}
catch (Exception)
{
// ignore exceptions thrown by user supplied callback
}
}
}
private async void ListenerCallback(IAsyncResult result)
{
try
{
var context = _listener.EndGetContext(result);
if (context.Request.HttpMethod == "GET")
{
context.Response.StatusCode = 200;
context.Response.Headers.Add("Content-Type", "text/plain");
await _metrics.Expose(context.Response.OutputStream, ExposeOptions.Default);
}
else
{
context.Response.StatusCode = 405; // Method not allowed
}
context.Response.Close();
}
catch (ObjectDisposedException)
{
// Do not throw exception on shutdown
}
catch (HttpListenerException ex)
{
_logger.LogWarning(ex, "HTTP problem error while providing metric");
}
catch (Exception ex)
{
_logger.LogError(ex, "Unexpected error while providing metric");
}
finally
{
BeginContext();
}
}
/// <summary>
/// Starts exposing metrics.
/// </summary>
public PrometheusServer(IOptions <PrometheusServerOptions> options, ILogger <PrometheusServer> logger, IExposable metrics)
{
string prefix = $"http://*:{options.Value.Port}/";
try
{
_listener = new HttpListener {
Prefixes = { prefix }
};
_listener.Start();
_listener.BeginGetContext(ListenerCallback, _listener);
}
catch (ObjectDisposedException)
{
// Do not throw exception on shutdown
}
catch (Exception ex) when(Environment.OSVersion.Platform == PlatformID.Win32NT)
{
logger.LogCritical(ex, "Please run the following as admin and then retry:\nnetsh http add urlacl {0} user={1}\\{2}",
prefix, Environment.GetEnvironmentVariable("USERDOMAIN"), Environment.GetEnvironmentVariable("USERNAME"));
throw;
}
async void ListenerCallback(IAsyncResult result)
{
try
{
var context = _listener.EndGetContext(result);
if (context.Request.HttpMethod == "GET")
{
context.Response.StatusCode = 200;
context.Response.Headers.Add("Content-Type", "text/plain");
await metrics.Expose(context.Response.OutputStream, ExposeOptions.Default);
}
else
{
context.Response.StatusCode = 405; // Method not allowed
}
context.Response.Close();
}
catch (ObjectDisposedException)
{
// Do not throw exception on shutdown
}
catch (HttpListenerException ex)
{
logger.LogWarning(ex, "HTTP problem error while providing metric");
}
catch (Exception ex)
{
logger.LogError(ex, "Unexpected error while providing metric");
}
finally
{
_listener.BeginGetContext(ListenerCallback, _listener);
}
}
}
/// <summary>
/// Pushes a metric to the push gateway.
/// </summary>
/// <param name="metrics">The metric to push.</param>
/// <param name="job">The job name used by prometheus, this should be a unique name for the type of service. Must be a valid Prometheus label.</param>
public void Push(IExposable metrics, string job)
{
Validate(metrics, job);
// It would be better to have a buffered stream
using (var ms = new MemoryStream())
{
metrics.Expose(ms, ExposeOptions.NoTimestamp).ConfigureAwait(false).GetAwaiter().GetResult();
ms.Position = 0;
var response = client.SendAsync(CreateRequestMessage(metrics, job, ms)).ConfigureAwait(false).GetAwaiter().GetResult();
if (!response.IsSuccessStatusCode)
{
throw new PushGatewayException($"Error pushing to gateway: {response.StatusCode}: {response.ReasonPhrase}");
}
}
}
public async Task Invoke(HttpContext context)
{
var sw = Stopwatch.StartNew();
context.Response.StatusCode = 200;
context.Response.Headers["Content-Type"] = "text/plain; version=0.0.4; charset=utf-8";
using (var writer = new StreamWriter(context.Response.Body, PrometheusConventions.PrometheusEncoding, 128, true))
{
writer.NewLine = "\n";
await writer.WriteLineAsync("# Exposing Nexogen.Libraries.Metrics.Prometheus\n");
await writer.FlushAsync();
await exposable.Expose(context.Response.Body, ExposeOptions.Default);
await writer.WriteLineAsync($"# Elapsed: {sw.ElapsedMilliseconds}ms");
}
}
/// <summary>
/// Pushes a metric to the push gateway asynchronously .
/// </summary>
/// <param name="metrics">The metric to push.</param>
/// <param name="job">The job name used by prometheus, this should be a unique name for the type of service. Must be a valid Prometheus label.</param>
/// <returns>An awaitable Task</returns>
public async Task PushAsync(IExposable metrics, string job)
{
Validate(metrics, job);
// It would be better to have a buffered stream
using (var ms = new MemoryStream())
{
await metrics.Expose(ms, ExposeOptions.NoTimestamp);
ms.Position = 0;
var response = await client.SendAsync(CreateRequestMessage(metrics, job, ms));
if (!response.IsSuccessStatusCode)
{
var message = await response.Content.ReadAsStringAsync();
throw new PushGatewayException($"Error pushing to gateway: {response.StatusCode}: {message}");
}
}
}