Linux Nginx子目录托管多个.NET Core7应用静态资源加载失败

问题根源 #

1. Nginx反向代理配置冗余：反向代理的location块中无需root指令，因为请求是转发到本地.NET应用处理，Nginx不需要直接指定静态文件根目录，多余的root会干扰路径解析。
2. .NET中间件顺序错误：UsePathBase必须在UseStaticFiles之前执行，否则路径基配置不会生效。
3. 资源URL生成错误：应用默认从根路径加载资源（如/css/style.css），未带上子目录前缀（如/auth/css/style.css），导致浏览器请求错误路径。

修复步骤 #

1. 修正Nginx服务器块配置 #

移除反向代理location中的root指令，修改后的完整配置如下：

server {
    server_name subdomain.domain.co.za www.subdomain.domain.co.za;
    error_log /var/apps/domain.co.za/logs/domain.log;
    
    root /var/www/subdomain.domain.co.za;

    location /proxy/ {
        proxy_pass         http://localhost:8886/;
        proxy_http_version 1.1;
        proxy_set_header   Upgrade $http_upgrade;
        proxy_set_header   Connection keep-alive;
        proxy_set_header   Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Proto $scheme;
    }

    location /auth/ {
        proxy_pass         http://localhost:8888/;
        proxy_http_version 1.1;
        proxy_set_header   Upgrade $http_upgrade;
        proxy_set_header   Connection keep-alive;
        proxy_set_header   Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Proto $scheme;  
    }

    location /api/ {
        proxy_pass         http://localhost:8887/;
        proxy_http_version 1.1;
        proxy_set_header   Upgrade $http_upgrade;
        proxy_set_header   Connection keep-alive;
        proxy_set_header   Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header   X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header   X-Forwarded-Proto $scheme;  
    }
    
    location / {
        root /var/www/subdomain.domain.co.za;
        index index.html;
    }

    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/subdomain.domain.co.za/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/subdomain.domain.co.za/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
}

server {
    if ($host = www.subdomain.domain.co.za) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    if ($host = subdomain.domain.co.za) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    server_name subdomain.domain.co.za www.subdomain.domain.co.za;
    listen 80;
    return 404; # managed by Certbot
}

2. 调整.NET Core应用的中间件配置 #

针对auth应用，先启用转发头处理，再设置路径基，最后配置静态文件，确保中间件顺序正确：

// 启用转发头处理，让应用识别反向代理传递的路径信息
app.UseForwardedHeaders(new ForwardedHeadersOptions
{
    ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto
});

// 设置路径基，必须在UseStaticFiles之前调用
app.UsePathBase("/auth");

// 配置静态文件，RequestPath对应路径基，FileProvider指向应用自身的wwwroot目录
app.UseStaticFiles(new StaticFileOptions
{
    RequestPath = "/auth",
    FileProvider = new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(), "wwwroot"))
});

// 后续路由、授权等中间件
app.UseRouting();
// ... 其他业务中间件配置

3. 修正视图中的资源路径写法 #

在Razor视图或HTML文件中，不要使用绝对根路径加载资源，改用.NET辅助方法自动添加子目录前缀：

<!-- 错误写法：绝对根路径 -->
<link rel="stylesheet" href="/css/site.css">

<!-- 正确写法1：使用Url.Content辅助方法 -->
<link rel="stylesheet" href="@Url.Content("~/css/site.css")">

<!-- 正确写法2：使用Tag Helper -->
<link rel="stylesheet" asp-src="~/css/site.css">

4. 重启服务验证 #

• 重启Nginx：sudo systemctl restart nginx
• 重启对应.NET Core应用（根据你的服务名调整）：sudo systemctl restart auth-app.service
• 打开浏览器开发者工具，检查资源请求路径是否已带上/auth前缀，确认返回200状态码。

内容的提问来源于stack exchange，提问作者Okuhle