[Yugong series] March 2022 asp Net core Middleware - conditional routing

Preface

1. Introduction to conditional routing

First of all, we have to understand what is routing rules ？ Suppose there is such a scenario, as shown in the figure below ：

In the figure above, we can see that there are two machine rooms, namely the machine room A、 Computer room B, Including machine room A Only access to Service A and Service B , And the computer room B Only access to Service C and Service D. To realize the above scenario, we need to use the so-called routing rules . Routing rules are initiated once RPC Filter the target server address before calling , And the filtered address list , Will be the final launch of the consumer side RPC Alternative address for the call . stay Dubbo Two routing rules are supported in. Today, we mainly discuss conditional routing .

Conditional routing ： Support the configuration of routing rules at the granularity of interface services or consumer applications .

2. Use scenarios

1. The blacklist ： For example, we need to prohibit certain service consumers from consuming Services

host = 192.168.53.10,192.168.53.11

The above configuration indicates that 192.168.53.10、192.168.53.11 Consumers access service providers .

2. Service boarding in application , Only a part of the machine is exposed , Prevent the whole cluster from hanging up

host = 192.168.53.1*,192.168.53.2*

The above configuration indicates that only 192.168.53.1*、192.168.53.2 ip The service provider at the beginning of the address .

3. Read / write separation ： Read data and write data operations are separated

method = find*,list*,get*,is* => host = 192.168.53.10,192.168.53.11,192.168.53.12method != find*,list*,get*,is* => host = 192.168.20.97,192.168.53.21

The above configuration indicates that find*,list*,get*,is* Method names start with methods that can only access 192.168.53.10,192.168.53.11,192.168.53.12 Service providers , instead of find*,list*,get*,is* Method names start with methods that can only access 192.168.20.97,192.168.53.21 Service providers .

4. Providers and consumers are deployed in the same cluster , This machine only accesses the service of this machine

host = $host

The above configuration indicates that all consumers can only access the services in the cluster .

Two 、ASP.NET Core Middleware conditional routing

Common implementation

endpoints.MapGet("/test2/{key:alpha}", async context =>{    var key = context.Request.RouteValues["key"].ToString();    foreach (var provider in Configuration.Providers.Reverse())    {        if (provider.TryGet(key, out string value))        {            await context.Response.WriteAsync(provider.ToString());            await context.Response.WriteAsync("\r\n");            await context.Response.WriteAsync(value);            break;        }    }});

But it is certain that they will be exposed in the production environment , To prevent exposure, you can use middleware .

1. Middleware code

public class DebugMiddleware : IMiddleware{    public async Task InvokeAsync(HttpContext context, RequestDelegate next)    {        var isDebugEndpoint = context.Request.Path.Value.Contains("/test");        var debugKey = context.Request.Query["debugKey"].ToString();        var debugKeyInConfig = "123456";// From configuration         if (isDebugEndpoint && debugKey!=debugKeyInConfig)        {            context.SetEndpoint(new Endpoint((context) =>            {                context.Response.StatusCode = StatusCodes.Status403Forbidden;                return Task.CompletedTask;            },                        EndpointMetadataCollection.Empty,                        " No access "));        }        await next(context);                }}

2. Use in pipes

app.UseMiddleware<DebugMiddleware >()