Startup.cs

using Honeycomb.OpenTelemetry;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using OpenTelemetry.Trace;
using StackExchange.Redis;
using System;

namespace message_service
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "message_service", Version = "v1" });
            });

            HoneycombOptions honeycombOptions = Configuration.GetHoneycombOptions();
            services.AddOpenTelemetry().WithTracing(otelBuilder =>
            {
                otelBuilder
                    .AddHoneycomb(honeycombOptions)
                    .AddCommonInstrumentations()
                    .AddAspNetCoreInstrumentation();
            });
            services.AddSingleton(TracerProvider.Default.GetTracer(honeycombOptions.ServiceName));

            var redisConfigString = Environment.GetEnvironmentVariable("REDIS_URL");
            if (string.IsNullOrWhiteSpace(redisConfigString))
            {
                redisConfigString = "localhost";
            }

            var redisOptions = ConfigurationOptions.Parse(redisConfigString);
            redisOptions.AbortOnConnectFail = false; // allow for reconnects if redis is not available
            var multiplexer = ConnectionMultiplexer.Connect(redisOptions);
            services.AddSingleton<IConnectionMultiplexer>(multiplexer);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "message_service v1"));
            }

            app.UseRouting();

            app.UseEndpoints(endpoints => endpoints.MapControllers());
        }
    }
}