nginx 502 - нет прямых апстримов при подключении к апстриму

Question

Nginx показывает мне ошибку 502 (нет прямых восходящих потоков при подключении к восходящему потоку). Для nginx у меня есть varnihs, прослушивающие порт 6081.

Моя конфигурация:

    upstream varnish {
           server 127.0.0.1:6081;
           server 127.0.1.1:6081;
    }

    location ~ / {
            proxy_pass http://varnish;
            proxy_intercept_errors on;
            proxy_set_header X-Real-IP  $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
            proxy_request_buffering off;
            proxy_buffering off;
    }

    access_log /var/log/nginx/access.log upstream_time;
    access_log /var/log/nginx/upstream.log upstream_log;
    error_log /var/log/nginx/error.log error;

################################################ ############################################### #

user www-data;
worker_processes auto;
pid /run/nginx.pid;
worker_rlimit_nofile 100480;
events {
        worker_connections 3000;
}
http {
        sendfile on;
        tcp_nopush on;
        tcp_nodelay on;
        keepalive_timeout 30;
        types_hash_max_size 2048;
        server_tokens off;
        reset_timedout_connection on;
        client_body_timeout 12;
        send_timeout 2;
        keepalive_requests 100;
        include /etc/nginx/mime.types;
        default_type application/octet-stream;
        ssl_protocols TLSv1.2; # Dropping SSLv3, ref: POODLE
        ssl_prefer_server_ciphers on;
}

Журналы (ошибка):

2020/08/03 21:02:43 [error] 3692#3692: *3505459612 no live upstreams while connecting to upstream, client: X.X.X.X, server: XXXXXXXXX, request: "GET XXXXXXXXXXXXXXXXXXXX HTTP/1.0", upstream: "http://varnish/XXXXXXXXXX", host: "XXXXXXXXX"

2020/08/03 21:02:43 [error] 3692#3692: *3505459613 no live upstreams while connecting to upstream, client: X.X.X.X, server: XXXXXXXXX, request: "GET XXXXXXXXXXXXXXXXXXXX HTTP/1.0", upstream: "http://varnish/XXXXXXXXXX", host: "XXXXXXXXX"

2020/08/03 21:02:43 [error] 3692#3692: *3505459614 no live upstreams while connecting to upstream, client: X.X.X.X, server: XXXXXXXXX, request: "GET XXXXXXXXXXXXXXXXXXXX HTTP/1.0", upstream: "http://varnish/XXXXXXXXXX", host: "XXXXXXXXX"


[03/Aug/2020:21:02:48 +0200] X.X.X.X - - - XXXXX hostX to: varnish: GET XXXXXXXXXXX HTTP/1.0 502 upstream_response_time 0.000 msec 1596481368.967 request_time 0.000

[03/Aug/2020:21:02:48 +0200] X.X.X.X - - - XXXXX hostX to: varnish: GET XXXXXXXXXXX HTTP/1.0 502 upstream_response_time 0.000 msec 1596481368.968 request_time 0.000

[03/Aug/2020:21:02:48 +0200] X.X.X.X - - - XXXXX hostX to: varnish: GET XXXXXXXXXXX HTTP/1.0 502 upstream_response_time 0.000 msec 1596481368.969 request_time 0.000


Logs (success):

[03/Aug/2020:00:08:31 +0200] X.X.X.X - - - XXXXX hostX to: 127.0.1.1:6081: GET XXXXXXXXXXX HTTP/1.1 200 upstream_response_time 0.000 msec 1596406111.634 request_time 0.000

[03/Aug/2020:00:08:31 +0200] X.X.X.X - - - XXXXX hostX to: 127.0.0.1:6081: GET XXXXXXXXXXX HTTP/1.0 200 upstream_response_time 0.016 msec 1596406111.634 request_time 0.017

[03/Aug/2020:00:08:31 +0200] X.X.X.X - - - XXXXX hostX to: 127.0.0.1:6081: GET XXXXXXXXXXX HTTP/1.1 200 upstream_response_time 0.004 msec 1596406111.635 request_time 0.004

как вы можете видеть, когда запрос получает правильный ответ, в журналах написано "hostX to: 127.0.1.1:6081" или "hostX to: 127.0.0.1:6081"

при получении неправильного ответа на запрос мы видим в логах: "hostX to: varnish"

У вас есть идеи, что может быть не так