Nginx reverse proxy and path location - docker

Question

Hello I'm new to the world of Docker, so I tried an installation with NGINX reverse proxy (jwilder image) and a Docker app.
I have installed both without SSL to make it easy. Since the Docker app seems to be installed in the root path I want to separate the NGINX web server and the docker app.
upstream example.com {
server 172.29.12.2:4040;
}
server {
server_name example.com;
listen 80 ;
access_log /var/log/nginx/access.log vhost;
location / {
proxy_pass http://example.com;
root /usr/share/nginx/html;
index index.html index.htm;
}
location /app {
proxy_pass http://example.com:4040;
}
}
So I want with http://example.com be redirected to the index.html
and with http://example.com/app be redirected to the docker app.
Furthermore, when I build the installation, I use in docker-compose expose: "4040" so when I reload NGINX configuration file with nginx -s reload, it warns me that I have not the port 4040 open.
With the configuration file I posted above any path lead me to the docker app.
I can't find a simple solution to my question.

Answer 1

As I far I understood your logic is right, docker is designed to run a single service to a single container; to reach your goal you still have a couple of thing to look after, if the EXPOSE 4040 was declared in you Docker file, that is not enough to let service reachable. in the docker-compose file you have to declare also the ports, I.E. for nginx you let host system to listen on all interface by adding
...
ports:
- 80:80
...
and this is the first thing, also you have to think on which way you want your proxy reach the "app", from the container network on the same node? If yes you can add in the composer file:
...
depends_on:
- app
...
where app is the declared name of your service in the docker-compose file like this nginx are able to reach your app with name app, so redirect will point to app:
location /app {
proxy_pass http://app:4040;
}
In case you want to reach the "app" via host network, may because one day will run in another host, you can add entry in the hosts file of the container run nginx with:
...
extra_hosts:
- "app:10.10.10.10"
- "appb:10.10.10.11"
...
and so on
Reference: https://docs.docker.com/compose/compose-file/
edit 01/01/2019!!!!! happy new year!!
an example using an "huge" docker compose file:
version: '3'
services:
app:
build: "./app" # in case you docker file is in a app dir
image: "some image name"
restart: always
command: "command to start your app"
nginx:
build: "./nginx" # in case you docker file is in a nginx dir
image: "some image name"
restart: always
ports:
- "80:80"
- "443:443"
depends_on:
- app
In the above example nginx can reach yuor app just with the "app" name so redirect will point to http://app:4040
systemctl (start directly with docker - no compose)
[Unit]
Description=app dockerized service
Requires=docker.service
After=docker.service
[Service]
ExecStartPre=/usr/bin/sleep 1
ExecStartPre=/usr/bin/docker pull mariadb:10.4
ExecStart=/usr/bin/docker run --restart=always --name=app -p 4040:4040 python:3.6-alpine # or your own builded image
ExecStop=/usr/bin/docker stop app
ExecStopPost=/usr/bin/docker rm -f app
ExecReload=/usr/bin/docker restart app
[Install]
WantedBy=multi-user.target
like the above example you can reach the app at port 4040 on the system host (which is in listen for connection on port 4040 by all interfaces) to give a specific interface: -p 10.10.10.10:4040:4040 like this will listen to port 4040 on address 10.10.10.10 (host machine)
docker-compose with extra_host:
version: '3'
services:
app:
build: "./app" # in case you docker file is in a app dir
image: "some image name"
restart: always
command: "command to start your app"
nginx:
build: "./nginx" # in case you docker file is in a nginx dir
image: "some image name"
restart: always
ports:
- "80:80"
- "443:443"
extra_hosts:
- "app:10.10.10.10"
like the above example nginx defined service can reach the name app at 10.10.10.10
least but not last extends service on compose file:
docker-compose.yml:
version: '2.1'
services:
app:
extends:
file: /path/to/app-service.yml
service: app
nginx:
extends: /path/to/nginx-service.yml
service: nginx
app-service.yml:
version: "2.1"
service:
app:
build: "./app" # in case you docker file is in a app dir
image: "some image name"
restart: always
command: "command to start your app"
nginx-service.yml
version: "2.1"
service:
nginx:
build: "./nginx" # in case you docker file is in a nginx dir
image: "some image name"
restart: always
ports:
- "80:80"
- "443:443"
extra_hosts:
- "app:10.10.10.10"
really hope the above posted are enough examples.