How to get the ServiceContext of a Reliable Service in Service Fabric?

Question

The ServiceContext of a reliable service in Service Fabric is registered with the runtime (DI container) in the program.cs of the service:

ServiceRuntime.RegisterServiceAsync("RelDictQuerySvcType",
                    context => new RelDictQuerySvc(context)).GetAwaiter().GetResult();

How can I get that ServiceContext back from the DI container? There is no property on the ServiceRuntime to get it back. Also, I did not find it via the FabricClient. Do I need to put the context on an own static class in the service constructor to be able to get a reference to it somewhere else in my code?

Answer 1

Service Fabric does not really has a build-in DI mechanism, at least it is a very simple one.

If you want to inject dependencies into you services itself you can use a factory. for example:

ServiceRuntime.RegisterServiceAsync("MyStatelessType",
                context =>
                {
                    var loggerFactory = new LoggerFactoryBuilder(context).CreateLoggerFactory(applicationInsightsKey);
                    ILogger logger = loggerFactory.CreateLogger<MyStateless>();

                    return new MyStateless(context, logger);
                }).GetAwaiter().GetResult();

this is a way to inject concrete implementations in your service. This mechanism is used to inject the context as well. Unfortunately, since it is not a full fledged DI container you cannot get this context outside the service instance itself.

So, you have to bring your own DI container to really use it, for example in a stateless web api you can do something like:

    protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
    {
        return new[]
        {
            new ServiceInstanceListener(serviceContext =>
                new WebListenerCommunicationListener(serviceContext, "ServiceEndpoint", (url, listener) =>
                {
                    logger.LogStatelessServiceStartedListening<WebApi>(url);

                    return new WebHostBuilder().UseWebListener()
                                .ConfigureServices(
                                    services => services
                                        .AddSingleton(serviceContext)
                                        .AddSingleton(logger)
                                        .AddTransient<IServiceRemoting, ServiceRemoting>())
                                .UseContentRoot(Directory.GetCurrentDirectory())
                                .UseServiceFabricIntegration(listener, ServiceFabricIntegrationOptions.None)
                                .UseStartup<Startup>()
                                .UseUrls(url)
                                .Build();
                }))
        };
    }

Otherwise you have to do it yourself. There are some initiatives already, see this one for an AutoFac extensions and there is also a Unity extensions.