代理OWIN自托管Web API中Swashbuckle的HTTPS端口异常问题

你的问题是Swashbuckle自动生成的API根URL错误带上了HTTPS不应该有的80端口，导致Swagger UI请求地址无效。可以通过配置RootUrl方法强制指定正确的根URL来解决：

方法一：硬编码固定根URL #

适合部署环境固定的场景，直接指定正确的根地址：

configSwag.EnableSwagger("docs/{apiVersion}/swagger", c =>
{
    var baseDirectory = AppDomain.CurrentDomain.BaseDirectory;
    var commentsFileName = Assembly.GetExecutingAssembly().GetName().Name + ".XML";
    var commentsFile = Path.Combine(baseDirectory, commentsFileName);

    c.Schemes(new string[] { "https" });
    // 指定正确的根URL，去掉多余的80端口
    c.RootUrl(_ => "https://api.domain.com");

    c.SingleApiVersion("v1", "MechaChat v1 Docs");
    c.IncludeXmlComments(commentsFile);
    c.PrettyPrint();
}).EnableSwaggerUi("v1/docs/{*assetPath}", c =>
{
    c.DocExpansion(DocExpansion.List);
    c.SupportedSubmitMethods("GET", "POST");
});

方法二：从代理请求头动态获取（更灵活） #

如果API部署在反向代理之后，可以从代理传递的请求头（如X-Forwarded-Host）动态获取主机地址，适配多环境：

configSwag.EnableSwagger("docs/{apiVersion}/swagger", c =>
{
    var baseDirectory = AppDomain.CurrentDomain.BaseDirectory;
    var commentsFileName = Assembly.GetExecutingAssembly().GetName().Name + ".XML";
    var commentsFile = Path.Combine(baseDirectory, commentsFileName);

    c.Schemes(new string[] { "https" });
    // 从代理头获取主机地址，无值时fallback到固定地址
    c.RootUrl(req =>
    {
        if (req.Headers.ContainsKey("X-Forwarded-Host"))
        {
            var forwardedHost = req.Headers.GetValues("X-Forwarded-Host").FirstOrDefault();
            if (!string.IsNullOrEmpty(forwardedHost))
            {
                return $"https://{forwardedHost}";
            }
        }
        return "https://api.domain.com";
    });

    c.SingleApiVersion("v1", "MechaChat v1 Docs");
    c.IncludeXmlComments(commentsFile);
    c.PrettyPrint();
}).EnableSwaggerUi("v1/docs/{*assetPath}", c =>
{
    c.DocExpansion(DocExpansion.List);
    c.SupportedSubmitMethods("GET", "POST");
});

原理：RootUrl方法会覆盖Swashbuckle自动推导的根URL，确保生成的API地址使用正确的HTTPS主机地址，不再错误附加80端口。

内容的提问来源于stack exchange，提问作者Xd_Golden_Tiger