502 Bad Gateway

1. 발생 조건

• upstream 서버가 모두 down 되어있을 때 - connection refused

2020/06/15 15:21:32 [error] 19845#19845: *15 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: naver.com, request: "GET /ping HTTP/1.1", upstream: "http://127.0.0.1:8001/ping", host: "127.0.0.1:8081"

504 Gateway Time-out

• 응답이 제한시간 내로 오지 않을 때 - Connection time out

    server {
        location / {        
            proxy_read_timeout 5s;            // proxy_read_timeout 이 5초이면, 응답이 5초 내로 안올 때 504 에러
            proxy_connect_timeout 1s;
               
            proxy_pass http://wascluster;

        }

// + /var/log/nginx/error.log
2020/06/15 15:19:43 [error] 19845#19845: *13 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 127.0.0.1, server: naver.com, request: "GET /ping HTTP/1.1", upstream: "http://127.0.0.1:8001/ping", host: "127.0.0.1:8081"