Connection refused by upstream nodes

[charliebaer]

/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3001/", host: "localhost:8080"
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3001/", host: "localhost:8080"
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3002/", host: "localhost:8080"
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3002/", host: "localhost:8080"
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3003/", host: "localhost:8080"
2020/10/17 11:50:56 [error] 28#28: *2 connect() failed (111: Connection refused) while connecting to upstream, client: 172.17.0.1, server: , request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:3003/", host: "localhost:8080"
172.17.0.1 - - [17/Oct/2020:11:50:56 +0000] "GET / HTTP/1.1" 502 157 "-" "PostmanRuntime/7.26.5"