通过依赖注入使用 Blazor Webassemble 进行 gRPC-Web 通道身份验证

我正在 Blazor Web assembly 中通过身份验证测试 gRPC-Web，并在如何干净地访问我的 gRPC 通道方面遇到了一些障碍。

无需身份验证，有一种非常简单明了的方法，如 grpc-dotnet 的 Blazor 示例中详细介绍的https://github.com/grpc/grpc-dotnet/tree/master/examples/Blazor https://github.com/grpc/grpc-dotnet/tree/master/examples/Blazor.

渠道的提供：

builder.Services.AddSingleton(services =>
{
    // Get the service address from appsettings.json
    var config = services.GetRequiredService<IConfiguration>();
    var backendUrl = config["BackendUrl"];

    var httpClient = new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWebText, new HttpClientHandler()));

    var channel = GrpcChannel.ForAddress(backendUrl, new GrpcChannelOptions { HttpClient = httpClient });

    return channel;
});

Razor 文件中的用法

@inject GrpcChannel Channel

直接在 razor 文件中添加身份验证并创建通道也没有那么复杂

@inject IAccessTokenProvider AuthenticationService
...

@code {
...
var httpClient = new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWebText, new HttpClientHandler()));
var tokenResult = await AuthenticationService.RequestAccessToken();

if (tokenResult.TryGetToken(out var token))
{
    var _token = token.Value;

    var credentials = CallCredentials.FromInterceptor((context, metadata) =>
    {
        if (!string.IsNullOrEmpty(_token))
        {
            metadata.Add("Authorization", $"Bearer {_token}");
        }
        return Task.CompletedTask;
    });

    //SslCredentials is used here because this channel is using TLS.
    //Channels that aren't using TLS should use ChannelCredentials.Insecure instead.
    var channel = GrpcChannel.ForAddress(baseUri, new GrpcChannelOptions
    {
        Credentials = ChannelCredentials.Create(new SslCredentials(), credentials)
    });

但这会将许多所需的逻辑移至 razor 文件中。有没有办法将这些结合起来并通过注入提供经过身份验证的 grpc 通道？

经过大量额外的测试，我找到了解决方案。 虽然不完美，但到目前为止运行良好。

启动期间注册频道

builder.Services.AddSingleton(async services =>
{
    var httpClient = new HttpClient(new GrpcWebHandler(GrpcWebMode.GrpcWeb, new HttpClientHandler()));
    var baseUri = "serviceUri";

    var authenticationService = services.GetRequiredService<IAccessTokenProvider>();

    var tokenResult = await authenticationService.RequestAccessToken();

    if(tokenResult.TryGetToken(out var token)) {
        var credentials = CallCredentials.FromInterceptor((context, metadata) =>
        {
            if (!string.IsNullOrEmpty(token.Value))
            {
                metadata.Add("Authorization", $"Bearer {token.Value}");
            }
            return Task.CompletedTask;
        });

        var channel = GrpcChannel.ForAddress(baseUri, new GrpcChannelOptions { HttpClient = httpClient, Credentials = ChannelCredentials.Create(new SslCredentials(), credentials) });

        return channel;
    }

    return GrpcChannel.ForAddress(baseUri, new GrpcChannelOptions() { HttpClient = httpClient });

});

由于通道是使用异步注册的，因此必须将其作为任务注入

@inject Task<GrpcChannel> Channel