翻译What I want to achive is load balancing using this stack: Docker, Docker Compose, Registrator, Consul, Consul Template, NGINX and, finally, a tiny service that prints out "Hello world" in browser. So, at this moment I have a docker-compose.yml file. It looks like so:
version: '2' services: accent: build: context: ./accent image: accent container_name: accent restart: always ports: - 80 consul: image: gliderlabs/consul-server:latest container_name: consul hostname: ${MYHOST} restart: always ports: - 8300:8300 - 8400:8400 - 8500:8500 - 8600:53/udp command: -advertise ${MYHOST} -data-dir /tmp/consul -bootstrap -client 0.0.0.0 registrator: image: gliderlabs/registrator:latest container_name: registrator hostname: ${MYHOST} network_mode: host restart: always volumes: - /var/run/docker.sock:/tmp/docker.sock command: -ip ${MYHOST} consul://${MYHOST}:8500 nginx: container_name: nginx image: nginx:latest restart: always volumes: - /etc/nginx ports: - 8181:80 consul-template: container_name: consul-template build: context: ./consul-template network_mode: host restart: always volumes_from: - nginx volumes: - /var/run/docker.sock:/tmp/docker.sock command: -consul=${MYHOST}:8500 -wait=5s -template="/etc/ctmpl/nginx.ctmpl:/etc/nginx/nginx.conf:docker kill -s HUP nginx"The first service - accent - is that my web service that I need to load balance. When I run this command:
$ docker-compose upI see that all services start to run and I see no error messages. It looks as if everything is just perfect. When I run
$ docker psI see this in the console:
... NAMES STATUS PORTS consul-template Up 45 seconds consul Up 56 seconds 0.0.0.0:8300->8300/tcp, 0.0.0.0:8400->8400/tcp, 8301-8302/tcp, 8301-8302/udp, 0.0.0.0:8500->8500/tcp, 8600/tcp, 8600/udp, 0.0.0.0:8600->53/udp nginx Up 41 seconds 0.0.0.0:8181->80/tcp registrator Up 56 seconds accent Up 56 seconds 0.0.0.0:32792->80/tcpPlease, pay attention to the last row and especially to PORTS column. As you can see, this service publishes 32792 port. To check that my web service is achievable I go to 127.0.0.1:32972 on my host machine (the machine where I run docker compose up) and see this in browser:
Hello WorldThis is exactly what I wanted to see. However, it is not what I finally want. Please, have a look at the output of docker ps command and you will see, that my nginx service published 8181 port. So, my expectation is that when I go to this address - 127.0.0.1:8181 - I will see exactly the same "Hello world" page. However, it is not. In browser I see Bad Gateway error message and in nginx logs I see this error message
nginx | 2017/01/18 06:16:45 [error] 5#5: *5 connect() failed (111: Connection refused) while connecting to upstream, client: 172.18.0.1, server: , request: "GET /favicon.ico HTTP/1.1", upstream: "http://127.0.0.1:32792/index.php", host: "127.0.0.1:8181"
It is really interesting, because nginx does what I expect it to do - upstreams to "http://127.0.0.1:32792/index.php". But I'm not sure why does it fail. By the way, this is how nginx.conf (created automatically with Consul Template) looks like:
worker_processes 1; events { worker_connections 1024; } http { sendfile on; upstream app_servers { server 127.0.0.1:32792; } server { listen 80; root /code; index index.php index.html; location / { try_files $uri/ $uri/ /index.php; } location ~ \.php$ { proxy_pass http://app_servers; proxy_redirect off; proxy_set_header Host $host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_set_header X-Forwarded-Host $server_name; } location ~ /\.ht { deny all; } } }I wouldn't change anything, since this nginx.conf looks good to me. Trying to understand why it does not work, I shelled to nginx container and made a couple of commands:
$ curl accent Hello World $ curl 127.0.0.1:32972 curl: (7) Failed to connect to 127.0.0.1 port 32972: Connection refused $ curl accent:32972 curl: (7) Failed to connect to accent port 32972: Connection refusedAgain, it is interesting, because nginx container sees my web service under port 80 and not under its published 32972 port. Anyway, at this stage I do not know why it does not work and how to fix it. I just have a guess, that it is somehow connected to the way, how network is configured in docker-compose.yml. I tried various combinations of network_mode: host on accent and nginx service, but to no avail - either accent stops working or nginx or both. So, I need some help.