Docker Compose Nginx Link containers - docker

Question

I have a docker compose container that runs Nginx. The site hosted is just a .test domain, like example.test.
Also in the container Nginx runs a location proxy and redirects it to example.test:8000. But it's not able to connect to that because that's actually being hosted from a different container on the same system (all bridged networks).
How can I let the containers communicate using example.test domain?
Or if I can't get them to communicate via example.test then how can I link them so they can use their docker-compose service name such as api or frontend?
Docker compose:
version: '3'
services:
db:
image: postgres
ports:
- "5432:5432"
django:
build: ./api
command: ["./docker_up.sh"]
restart: always
volumes:
- ./api:/app/api
- api-static:/app/api/staticfiles
ports:
- "8000:8000"
depends_on:
- db
environment:
- MODE=DEV
volumes:
frontend-build:
api-static:
certificates:
2nd compose file (run together):
version: '3'
services:
django:
environment:
- MODE=PROD
#links:
# - hosting
hosting:
build: ./hosting
restart: always
network_mode: bridge
volumes:
- frontend-build:/var/www
ports:
- "80:80"
- "443:443"
environment:
- MODE=PROD
#links:
# - django
volumes:
frontend-build:
With these current settings I get an error when I run it
ERROR: for 92b89f848637_opensrd_hosting_1 Cannot start service hosting: Cannot link to /opensrd_django_1, as it does not belong to the default network
Edit: Altered docker-compose.prod.yml:
networks:
app_net:
driver: bridge
ipam:
driver: default
config:
-
subnet: 172.16.238.0/24
services:
django:
environment:
- MODE=PROD
networks:
app_net:
ipv4_address: 172.16.238.10
But this gives me an error.
ERROR: The Compose file './docker-compose.prod.yml' is invalid because:
networks.app_net value Additional properties are not allowed ('config' was unexpected)
networks.app_net.ipam contains an invalid type, it should be an object

Answer 1

So I tried the options given by #trust512 and #DimaL, and those didn't work.
However after deleting the network and links from my compose files, and removing the existing default network and built containers, it worked, and I can not refer between container using db, django, and hosting.
The only thing different is I changed the composer version from 3 to 3.5.
These are the final files for anyone interested:
version: '3.5'
services:
db:
image: postgres
ports:
- "5432:5432"
django:
build: ./api
command: ["./docker_up.sh"]
restart: always
volumes:
- ./api:/app/api
- api-static:/app/api/staticfiles
ports:
- "8000:8000"
depends_on:
- db
environment:
- MODE=DEV
volumes:
frontend-build:
api-static:
docker-compose.prod.yml:
version: '3.5'
services:
django:
environment:
- MODE=PROD
hosting:
build: ./hosting
restart: always
volumes:
- frontend-build:/var/www
ports:
- "80:80"
- "443:443"
environment:
- MODE=PROD
volumes:
frontend-build:

Answer 2

You can use external_links (https://docs.docker.com/compose/compose-file/#external_links) or try to put all containers on the same virtual network.

Answer 3

As far as I understand you just want them (django and nginx) to be linked across composes?
Then a native solution would be to use external_links exampled here
And use it like this:
services:
[...]
hosting:
[...]
external_links:
- django_1:example
[...]
Where django_1 stands for the container name created by the compose you provided and example is the alias that the container will be visible inside Django container.
Other way round you can just point a example.test domain to a specific address by editing your /etc/hosts (provided you work on linux/mac)
for example by adding a record like
172.16.238.10 example.test
Where the address above would point to your django application (container).
The above can be achieved without altering your /etc/hosts by using native solution from compose (extra_hosts) documented here
Additionally if you prefer a static ip address for your django/nginx containers in case you stick to the /etc/hosts od extra_hosts solution you can utilize another native solution provided by compose that sets up a static ip for a chosen services, properly exampled here
A adjusted listing from the linked documentation:
services:
[...]
django:
[...]
networks:
app_net:
ipv4_address: 172.16.238.10
networks:
app_net:
driver: bridge
ipam:
driver: default
config:
-
subnet: 172.16.238.0/24