error日志：
2020/11/07 23:49:43 [error] 11008#4992: *24 connect() failed (10061: No connection could be made because the target machine actively refused it) while connecting to upstream, client: 127.0.0.1, server: localhost, request: “GET / HTTP/1.1”, upstream: “http://127.0.0.1:8081/”, host: "localhost:8085"
2020/11/07 23:49:45 [error] 11008#4992: *24 connect() failed (10061: No connection could be made because the target machine actively refused it) while connecting to upstream, client: 127.0.0.1, server: localhost, request: “GET / HTTP/1.1”, upstream: “http://[::1]:8081/”, host: "localhost:8085"
2020/11/07 23:49:50 [error] 11008#4992: *28 no live upstreams while connecting to upstream, client: 127.0.0.1, server: localhost, request: “GET /favicon.ico HTTP/1.1”, upstream: “http://localhost/favicon.ico”, host: “localhost:8085”, referrer: “http://localhost:8085/”