public ServiceDiscoveryRouterMiddleware(
RequestDelegate next,
ILogger <ServiceDiscoveryRouterMiddleware> logger,
IOptions <ServiceDiscoveryRouterMiddlewareOptions> options)
{
EnsureArg.IsNotNull(next, nameof(next));
EnsureArg.IsNotNull(logger, nameof(logger));
this.next = next;
this.logger = logger;
this.options = options.Value ?? new ServiceDiscoveryRouterMiddlewareOptions();
}
/// <summary>
/// Enables the service discovery router.
/// </summary>
/// <param name="naosOptions"></param>
/// <param name="options"></param>
public static NaosApplicationContextOptions UseNaosServiceDiscoveryRouter(
this NaosApplicationContextOptions naosOptions,
ServiceDiscoveryRouterMiddlewareOptions options)
{
EnsureArg.IsNotNull(naosOptions, nameof(naosOptions));
EnsureArg.IsNotNull(options, nameof(options));
#pragma warning disable CS0618 // Type or member is obsolete >> naosOptions.Context.Application.Map("/api/servicediscovery/router/proxy", async proxy => { proxy.UseProxy() } )
naosOptions.Context.Application.RunProxy("/naos/servicediscovery/router/proxy", async context =>
{
var logger = naosOptions.Context.Application.ApplicationServices.GetRequiredService <ILogger>();
var registryClient = naosOptions.Context.Application.ApplicationServices.GetRequiredService <RouterContext>().RegistryClient;
// read headers for service/tag
var isFoundName = context.Request.Headers.TryGetValue(ServiceDiscoveryRouterHeaders.ServiceName, out var serviceName);
var isFoundTag = context.Request.Headers.TryGetValue(ServiceDiscoveryRouterHeaders.ServiceTag, out var serviceTag);
if (!isFoundName && !isFoundTag)
{
context.Response.StatusCode = 400;
throw new NaosException($"Router cannot find a service registration based on the provided information (serviceName={serviceName}, serviceTag={serviceTag})");
// = 400 bad request (router headers missing)
}
var registrations = await registryClient.RegistrationsAsync(serviceName, serviceTag).AnyContext();
var registration = registrations.FirstOrDefault(); // todo: do some kind random/roundrobin
if (registration == null)
{
context.Response.StatusCode = 502;
throw new NaosException($"Router cannot find a service registration based on the provided information (serviceName={serviceName}, serviceTag={serviceTag})");
// = 404? 502? https://errorcodespro.com/what-is-http-error-502-bad-gateway/
}
// TODO: how is api/registrations NOT forwarded? based on missing router headers?
// TODO: round robin https://github.com/damianh/ProxyKit/blob/master/src/Recipes/05_RoundRobin.cs
var upstreamHost = new Uri($"{registration.Address}:{registration.Port}");
logger.LogInformation($"{{LogKey:l}} router {{Url}} >> {{Host}} (service={{ServiceName}}, tag={serviceTag})", LogKeys.ServiceDiscovery, context.Request.GetUri(), upstreamHost, registration.Name);
return(await context
.ForwardTo(upstreamHost)
.Log(logger)
.CopyXForwardedHeaders() // copies the headers from the incoming requests
.AddXForwardedHeaders() // adds the current proxy proto/host/for/pathbase to the X-Forwarded headers
.Send().AnyContext());
});
#pragma warning restore CS0618 // Type or member is obsolete
naosOptions.Context.Messages.Add("naos application builder: job scheduling added"); // TODO: list available commands/handlers
//return app.UseMiddleware<ServiceDiscoveryRouterMiddleware>(Options.Create(options));
return(naosOptions);
}
