健康檢測

TCP心跳檢查

upstream backend {
    server 192.168.61.1:9080 weight=1;
    server 192.168.61.1:9090 weight=2;
    check interval=3000 rise=1 fall=3 timeout=2000 type=tcp;
}

interval：檢測間隔時間
fall：檢測失敗多少次后，后端服務器標識為不存活
rise：檢測成功多少次后，后端服務器標識為存活
timeout：檢測請求超時時間配置

HTTP心跳檢測

upstream backend {
    server 192.168.61.1:9080 weight=1;
    server 192.168.61.1:9090 weight=2;

    check interval=3000 rise=1 fall=3 timeout=2000 type=http;
    check_http_send "HEAD /status HTTP/1.0\r\n\r\n";
    check_http_expect_alive http_2xx http_3xx;
}

check_http_send：檢查時發的HTTP請求內容
check_http_expect_alive：后端服務器返回匹配響應狀態碼，則認為后端服務器存活