samples/ReverseProxy.ConfigFilter.Sample/CustomConfigFilter.cs - main - aprogrammer/reverse-proxy-ms-yarp

samples/ReverseProxy.ConfigFilter.Sample/CustomConfigFilter.cs
67 строк3 KB
Kahbazi
Add cluster to ConfigureRouteAsync (#1231)
08 сен 2021, 02:08
08 сен 2021, 02:08bda7ace
// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using Yarp.ReverseProxy.Configuration;

namespace Yarp.Sample
{
    public class CustomConfigFilter : IProxyConfigFilter
    {
        // Matches {{env_var_name}}
        private readonly Regex _exp = new("\\{\\{(\\w+)\\}\\}");

        // Configuration filter for clusters, will be passed each cluster in turn, which it should either return as-is or
        // clone and create a new version of with updated changes
        //
        // This sample looks at the destination addresses and any of the form {{key}} will be modified, looking up the key
        // as an environment variable. This is useful when hosted in Azure etc, as it enables a simple way to replace
        // destination addresses via the management console
        public ValueTask<ClusterConfig> ConfigureClusterAsync(ClusterConfig origCluster, CancellationToken cancel)
        {
            // Each cluster has a dictionary of destinations, which is read-only, so we'll create a new one with our updates 
            var newDests = new Dictionary<string, DestinationConfig>(StringComparer.OrdinalIgnoreCase);

            foreach (var d in origCluster.Destinations)
            {
                var origAddress = d.Value.Address;
                if (_exp.IsMatch(origAddress))
                {
                    // Get the name of the env variable from the destination and lookup value
                    var lookup = _exp.Matches(origAddress)[0].Groups[1].Value;
                    var newAddress = System.Environment.GetEnvironmentVariable(lookup);

                    if (string.IsNullOrWhiteSpace(newAddress))
                    {
                        throw new System.ArgumentException($"Configuration Filter Error: Substitution for '{lookup}' in cluster '{d.Key}' not found as an environment variable.");
                    }

                    // using c# 9 "with" to clone and initialize a new record
                    var modifiedDest = d.Value with { Address = newAddress };
                    newDests.Add(d.Key, modifiedDest);
                }
                else
                {
                    newDests.Add(d.Key, d.Value);
                }
            }
            return new ValueTask<ClusterConfig>(origCluster with { Destinations = newDests });
        }

        public ValueTask<RouteConfig> ConfigureRouteAsync(RouteConfig route, ClusterConfig cluster, CancellationToken cancel)
        {
            // Example: do not let config based routes take priority over code based routes.
            // Lower numbers are higher priority. Code routes default to 0.
            if (route.Order.HasValue && route.Order.Value < 1)
            {
                return new ValueTask<RouteConfig>(route with { Order = 1 });
            }

            return new ValueTask<RouteConfig>(route);
        }
    }
}