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Nginx 如何配置日志？有哪些日志格式和优化方法？

2月21日 16:57

Nginx 如何配置日志？有哪些日志格式和优化方法？

Nginx 日志对于监控、调试和安全审计非常重要。合理配置日志可以帮助快速定位问题和优化性能。

访问日志配置：

nginx
http {
    # 自定义日志格式
    log_format main '$remote_addr - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent" '
                    '$request_time $upstream_response_time';
    
    # 详细日志格式
    log_format detailed '$remote_addr - $remote_user [$time_local] '
                      '"$request" $status $body_bytes_sent '
                      '"$http_referer" "$http_user_agent" '
                      '$request_time $upstream_response_time '
                      '$upstream_addr $upstream_status '
                      '$http_x_forwarded_for $request_id';
    
    # JSON 格式日志
    log_format json_combined escape=json '{'
        '"time_local":"$time_local",'
        '"remote_addr":"$remote_addr",'
        '"remote_user":"$remote_user",'
        '"request":"$request",'
        '"status":"$status",'
        '"body_bytes_sent":"$body_bytes_sent",'
        '"request_time":"$request_time",'
        '"http_referrer":"$http_referer",'
        '"http_user_agent":"$http_user_agent"'
    '}';
    
    # 应用日志格式
    access_log /var/log/nginx/access.log main;
    
    server {
        listen 80;
        server_name example.com;
        
        # 使用不同的日志格式
        access_log /var/log/nginx/example.com.access.log detailed;
        
        location / {
            proxy_pass http://backend;
        }
    }
}

错误日志配置：

nginx
# 错误日志级别：debug, info, notice, warn, error, crit, alert, emerg
error_log /var/log/nginx/error.log warn;

# 不同级别的错误日志
error_log /var/log/nginx/error.log info;
error_log /var/log/nginx/crit.log crit;

日志优化：

nginx
http {
    # 禁用特定路径的日志
    location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg|woff|woff2)$ {
        access_log off;
    }
    
    # 禁用健康检查日志
    location /health {
        access_log off;
        return 200 "OK";
    }
    
    # 缓冲日志写入
    access_log /var/log/nginx/access.log main buffer=32k flush=5s;
    
    # 压缩日志
    access_log /var/log/nginx/access.log main gzip=9;
}

条件日志记录：

nginx
http {
    # 根据状态码记录日志
    map $status $loggable {
        ~^[23]  0;
        default 1;
    }
    
    # 根据请求方法记录日志
    map $request_method $loggable_method {
        GET     1;
        POST    1;
        default 0;
    }
    
    server {
        listen 80;
        server_name example.com;
        
        # 只记录特定状态码的请求
        access_log /var/log/nginx/access.log main if=$loggable;
        
        # 只记录特定方法的请求
        access_log /var/log/nginx/method.log main if=$loggable_method;
        
        location / {
            proxy_pass http://backend;
        }
    }
}

分离日志：

nginx
http {
    # API 日志
    log_format api '$remote_addr - $remote_user [$time_local] '
                   '"$request" $status $body_bytes_sent '
                   'rt=$request_time uct="$upstream_connect_time" '
                   'uht="$upstream_header_time" urt="$upstream_response_time"';
    
    server {
        listen 80;
        server_name example.com;
        
        # 主站点日志
        access_log /var/log/nginx/main.log main;
        
        # API 日志
        location /api/ {
            access_log /var/log/nginx/api.log api;
            proxy_pass http://api_backend;
        }
        
        # 静态资源不记录
        location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg|woff|woff2)$ {
            access_log off;
            root /var/www/static;
        }
    }
}

日志轮转：

bash
# /etc/logrotate.d/nginx
/var/log/nginx/*.log {
    daily
    missingok
    rotate 14
    compress
    delaycompress
    notifempty
    create 0640 nginx adm
    sharedscripts
    postrotate
        [ -f /var/run/nginx.pid ] && kill -USR1 `cat /var/run/nginx.pid`
    endscript
}

日志分析变量：

nginx
log_format analysis '$remote_addr - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent" '
                    '$request_time $upstream_response_time '
                    '$upstream_addr $upstream_status '
                    '$scheme $server_name $request_uri '
                    '$http_host $http_x_forwarded_for '
                    '$request_id $connection $connections '
                    '$time_iso8601 $msec';

常用日志变量：

变量说明
$remote_addr客户端 IP 地址
$remote_user认证用户名
$time_local本地时间
$request完整的请求行
$status响应状态码
$body_bytes_sent发送的字节数
$http_referer来源页面
$http_user_agent用户代理
$request_time请求处理时间
$upstream_response_time上游响应时间
$upstream_addr上游服务器地址
$upstream_status上游状态码
$request_id请求 ID
$http_x_forwarded_for真实客户端 IP

日志监控和告警：

nginx
# 自定义错误日志格式
log_format error_log_format '$time_local [$level] $message';

# 记录慢请求
log_format slow_request '$remote_addr - $remote_user [$time_local] '
                      '"$request" $status $request_time '
                      'upstream_response_time=$upstream_response_time';

http {
    # 慢请求阈值
    map $request_time $slow_request {
        default 0;
        ~^([1-9]\d*\.?\d*|0\.\d*[1-9]\d*) 1;
    }
    
    server {
        listen 80;
        server_name example.com;
        
        # 记录慢请求
        access_log /var/log/nginx/slow.log slow_request if=$slow_request;
        
        location / {
            proxy_pass http://backend;
        }
    }
}

日志安全：

nginx
http {
    # 不记录敏感信息
    log_format secure '$remote_addr - $remote_user [$time_local] '
                     '"$request" $status $body_bytes_sent '
                     '"$http_referer" "$http_user_agent" '
                     '$request_time';
    
    server {
        listen 80;
        server_name example.com;
        
        # 不记录密码等敏感信息
        location /login {
            access_log /var/log/nginx/login.log secure;
            proxy_pass http://auth_backend;
        }
        
        # 不记录敏感路径
        location ~* ^/(admin|api/v1/users) {
            access_log /var/log/nginx/sensitive.log secure;
            proxy_pass http://backend;
        }
    }
}

完整日志配置示例：

nginx
user nginx;
worker_processes auto;

http {
    # 日志格式
    log_format main '$remote_addr - $remote_user [$time_local] '
                    '"$request" $status $body_bytes_sent '
                    '"$http_referer" "$http_user_agent" '
                    '$request_time $upstream_response_time';
    
    log_format api '$remote_addr - $remote_user [$time_local] '
                   '"$request" $status $body_bytes_sent '
                   'rt=$request_time uct="$upstream_connect_time" '
                   'uht="$upstream_header_time" urt="$upstream_response_time" '
                   'upstream_addr=$upstream_addr upstream_status=$upstream_status';
    
    log_format json_combined escape=json '{'
        '"time_local":"$time_local",'
        '"remote_addr":"$remote_addr",'
        '"remote_user":"$remote_user",'
        '"request":"$request",'
        '"status":"$status",'
        '"body_bytes_sent":"$body_bytes_sent",'
        '"request_time":"$request_time",'
        '"http_referrer":"$http_referer",'
        '"http_user_agent":"$http_user_agent",'
        '"upstream_response_time":"$upstream_response_time"'
    '}';
    
    # 全局日志
    access_log /var/log/nginx/access.log main buffer=32k flush=5s;
    error_log /var/log/nginx/error.log warn;
    
    # 条件日志
    map $status $loggable {
        ~^[23]  0;
        default 1;
    }
    
    # 慢请求
    map $request_time $slow_request {
        default 0;
        ~^([1-9]\d*\.?\d*|0\.\d*[1-9]\d*) 1;
    }
    
    server {
        listen 80;
        server_name example.com;
        
        # 主日志
        access_log /var/log/nginx/example.com.access.log main if=$loggable;
        
        # 慢请求日志
        access_log /var/log/nginx/slow.log main if=$slow_request;
        
        # API 日志
        location /api/ {
            access_log /var/log/nginx/api.log api;
            proxy_pass http://api_backend;
        }
        
        # 静态资源不记录
        location ~* \.(css|js|jpg|jpeg|png|gif|ico|svg|woff|woff2)$ {
            access_log off;
            root /var/www/static;
        }
        
        # 健康检查不记录
        location /health {
            access_log off;
            return 200 "OK";
        }
        
        location / {
            proxy_pass http://backend;
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        }
    }
}

日志分析工具：

  1. GoAccess：实时日志分析
  2. AWStats：Web 日志分析
  3. ELK Stack：Elasticsearch + Logstash + Kibana
  4. Grafana + Loki：日志监控和可视化
  5. Splunk：企业级日志分析

日志优化建议：

  1. 合理设置日志级别：生产环境使用 warn 或 error
  2. 使用缓冲：减少磁盘 I/O
  3. 定期轮转：避免日志文件过大
  4. 压缩旧日志：节省磁盘空间
  5. 分离日志：按业务类型分离
  6. 条件记录：只记录必要的信息
  7. 使用 JSON 格式：便于机器解析
  8. 监控日志大小：防止磁盘占满
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