Acoompanies this blog post: https://cultiv.nl/blog/setting-up-hangfire-in-umbraco-9/

HangfireComposer.cs

using System;
using Hangfire;
using Hangfire.Console;
using Hangfire.SqlServer;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Web.BackOffice.Authorization;
using Umbraco.Cms.Web.Common.ApplicationBuilder;

namespace Cultiv.Hangfire.Composers
{
    public class HangfireComposer : IComposer
    {
        public void Compose(IUmbracoBuilder builder)
        {
            // Configure Hangfire to use our current database and add the option to write console messages
            var connectionString = builder.Config.GetConnectionString(Umbraco.Cms.Core.Constants.System.UmbracoConnectionName);
            builder.Services.AddHangfire(configuration =>
            {
                configuration
                    .SetDataCompatibilityLevel(CompatibilityLevel.Version_170)
                    .UseSimpleAssemblyNameTypeSerializer()
                    .UseRecommendedSerializerSettings()
                    .UseConsole()
                    .UseSqlServerStorage(connectionString, new SqlServerStorageOptions
                    {
                        CommandBatchMaxTimeout = TimeSpan.FromMinutes(5),
                        SlidingInvisibilityTimeout = TimeSpan.FromMinutes(5),
                        QueuePollInterval = TimeSpan.Zero,
                        UseRecommendedIsolationLevel = true,
                        DisableGlobalLocks = true,
                    });
            });
            
            // Run the required server so your queued jobs will get executed
            builder.Services.AddHangfireServer();
            
            // Add a named policy to authorize requests to the dashboard
            builder.Services.AddAuthorization(options =>
            {
                options.AddPolicy("HangfireDashboard", policy =>
                {
                    // We require a logged in backoffice user who has access to the settings section
                    policy.AuthenticationSchemes.Add(Umbraco.Cms.Core.Constants.Security.BackOfficeAuthenticationType);
                    policy.Requirements.Add(new SectionRequirement(Umbraco.Cms.Core.Constants.Applications.Settings));
                });
            });
            
            // Add the dashboard and make sure it's authorized with the named policy above
            builder.Services.Configure<UmbracoPipelineOptions>(options =>
            {
                options.AddFilter(new UmbracoPipelineFilter("HangfireDashboard")
                {
                    Endpoints = app => app.UseEndpoints(endpoints =>
                    {
                        endpoints.MapHangfireDashboard(
                            pattern: "/umbraco/backoffice/hangfire",
                            options: new DashboardOptions()).RequireAuthorization("HangfireDashboard");
                    }).UseHangfireDashboard()
                });
            });
            
            // For some reason we need to give it the connection string again, else we get this error:
            // https://discuss.hangfire.io/t/jobstorage-current-property-value-has-not-been-initialized/884
            JobStorage.Current = new SqlServerStorage(connectionString);
            
            // Now we can queue our jobs
            var jobsQueue = new JobsQueue();
            jobsQueue.ScheduleJobs();
        }
    }
}