Earlier today I was attempting to set up a docker compose file containing a few different services, one of which was running nginx:latest. One of my other services was running on alpine:latest, and no matter what I tried I could not successfully curl the nginx service from the alpine container, and keep seeing Failed to connect to nginx port 80 errors from curl. Curling the nginx service from containers running other images seems to workout just fine.
In an attempt to recreate the issue, I have reduced the docker-compose.yml file as much as possible, and came up with this:
services: alpine-test: build: dockerfile: Dockerfile.alpine command: sleep 3600 networks: - test-network ubuntu-test: build: dockerfile: Dockerfile.ubuntu command: sleep 3600 networks: - test-network nginx: image: nginx:latest ports: - "8080:80" networks: - test-networknetworks: test-network: driver: bridgeDockerfile.ubuntu:
FROM ubuntu:latestRUN apt update -y && apt install -y curlDockerfile.alpine:
FROM alpine:latestRUN apk update && apk add curlI am spinning up the compose project with this command:
docker compose -f docker-compose.test.yaml up --force-recreate
Curling the nginx service from the ubuntu service:
docker exec proj-local-ubuntu-test-1 curl -vv http://nginx
Output:
% Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Trying 172.27.0.3:80...* Connected to nginx (172.27.0.3) port 80 (#0)> GET / HTTP/1.1> Host: nginx> User-Agent: curl/7.81.0> Accept: */*>* Mark bundle as not supporting multiuse< HTTP/1.1 200 OK< Server: nginx/1.27.0< Date: Fri, 14 Jun 2024 23:52:50 GMT< Content-Type: text/html< Content-Length: 615< Last-Modified: Tue, 28 May 2024 13:22:30 GMT< Connection: keep-alive< ETag: "6655da96-267"< Accept-Ranges: bytes<{ [615 bytes data]100 615 100 615 0 0 820k 0 --:--:-- --:--:-- --:--:-- 600k* Connection #0 to host nginx left intact<!DOCTYPE html><html><head><title>Welcome to nginx!</title><style>html { color-scheme: light dark; }body { width: 35em; margin: 0 auto;font-family: Tahoma, Verdana, Arial, sans-serif; }</style></head><body><h1>Welcome to nginx!</h1><p>If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.</p><p>For online documentation and support please refer to<a href="http://nginx.org/">nginx.org</a>.<br/>Commercial support is available at<a href="http://nginx.com/">nginx.com</a>.</p><p><em>Thank you for using nginx.</em></p></body></html>Curling the nginx service from the alpine service:
docker exec proj-local-alpine-test-1 curl -vv http://nginx
Output:
% Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Host nginx:80 was resolved.* IPv6: (none)* IPv4: 192.168.1.1* Trying 192.168.1.1:80... 0 0 0 0 0 0 0 0 --:--:-- 0:02:12 --:--:-- 0* connect to 192.168.1.1 port 80 from 172.27.0.3 port 54744 failed: Operation timed out* Failed to connect to nginx port 80 after 132953 ms: Couldn't connect to server 0 0 0 0 0 0 0 0 --:--:-- 0:02:12 --:--:-- 0* Closing connectioncurl: (28) Failed to connect to nginx port 80 after 132953 ms: Couldn't connect to serverThe containers all seem to be correctly sharing the same network:
[ {"Name": "cmapp-local_test-network","Id": "5a258b6b903fec157391704554845314423dd261614cbbffb5feb178edbfb0cb","Created": "2024-06-14T16:35:02.946998948-07:00","Scope": "local","Driver": "bridge","EnableIPv6": false,"IPAM": {"Driver": "default","Options": null,"Config": [ {"Subnet": "172.27.0.0/16","Gateway": "172.27.0.1" } ] },"Internal": false,"Attachable": false,"Ingress": false,"ConfigFrom": {"Network": "" },"ConfigOnly": false,"Containers": {"1a481a82e1aae822cacca707a997fca13d2a15a7a2ba9acaa2f67716f432301a": {"Name": "cmapp-local-alpine-test-1","EndpointID": "cda6b08db448c918e4d3763cbc1d6bb628ee592f9dc6c61d2cb5e2233fb7ffc0","MacAddress": "02:42:ac:1b:00:03","IPv4Address": "172.27.0.3/16","IPv6Address": "" },"78416ae61c2c86dec2b978ba07dcaf7dc96b17fcd6b608ef21a60b55a90a05d6": {"Name": "cmapp-local-ubuntu-test-1","EndpointID": "bf56252dd5a4b5ebd6cdab1f2c3b8653d64e5ced1d571b70c00caef2fc8722b8","MacAddress": "02:42:ac:1b:00:04","IPv4Address": "172.27.0.4/16","IPv6Address": "" },"a4e95ed049894930573c8d2713a832c27e5f8ef3d14196298e6c99c786aed25a": {"Name": "cmapp-local-nginx-1","EndpointID": "74f816a26ff1bafc5936fe67d2e4c750ca1fdaaeedb879ea01a9aec5225e4e35","MacAddress": "02:42:ac:1b:00:02","IPv4Address": "172.27.0.2/16","IPv6Address": "" } },"Options": {},"Labels": {"com.docker.compose.network": "test-network","com.docker.compose.project": "cmapp-local","com.docker.compose.version": "2.27.1" } }]The resolv.conf files from both the ubuntu and alpine containers look identical, presumably because docker generates them:
Ubuntu resolv.conf
# Generated by Docker Engine.# This file can be edited; Docker Engine will not make further changes once it# has been modified.nameserver 127.0.0.11search lanoptions edns0 trust-ad ndots:0# Based on host file: '/etc/resolv.conf' (internal resolver)# ExtServers: [host(127.0.0.53)]# Overrides: []# Option ndots from: internalAlpine resolv.conf
# Generated by Docker Engine.# This file can be edited; Docker Engine will not make further changes once it# has been modified.nameserver 127.0.0.11search lanoptions edns0 trust-ad ndots:0# Based on host file: '/etc/resolv.conf' (internal resolver)# ExtServers: [host(127.0.0.53)]# Overrides: []# Option ndots from: internalRunning nslookup in the alpine container returns some strange results:
Server: 127.0.0.11Address: 127.0.0.11:53Non-authoritative answer:Non-authoritative answer:Name: nginx.lanAddress: 192.168.1.1whereas the nslookup output in the ubuntu container are more what I was expecting:
Server: 127.0.0.11Address: 127.0.0.11#53Non-authoritative answer:Name: nginxAddress: 172.27.0.2Any help on this would be greatly appreciated. Thank you.