Hosts aren't accessible by name in docker compose on Windows - windows

Question

I have two, windows-based images that I'm using with docker compose.
The docker-compose.yaml:
services:
application:
image: myapp-win:latest
container_name: "my-app"
# for diagnosis
entrypoint: ["cmd"]
stdin_open: true
tty: true
# /diagnosis
env_file: .myapp/.env
environment:
- POSTGRES_URI=jdbc:postgresql://db0:5432/mydatabase
depends_on:
db0:
condition: service_healthy
db0:
image: stellirin/postgres-windows:10.10
container_name: "my-db"
ports:
- 10000:5432 # this doesn't seem to work in windows
env_file:
- .postgres/.env
volumes:
- .postgres\initdb\:c:\docker-entrypoint-initdb.d\
healthcheck:
test: [ "CMD", "pg_isready", "-q", "-d", "${POSTGRES_DATABASE}", "-U", "${POSTGRES_USER}" ]
timeout: 45s
interval: 10s
retries: 10
restart: unless-stopped
With the two containers started, I accessed the terminal for the my-db container and got its IP address.
Next, I accessed the terminal for the my-app container. I was able to ping the my-db container by its IP address. However, it did not respond by its hostname:
c:\app> ping db0
Ping request could not find host db0.
This is symptommatic why the application can't reach the database using the POSTGRES_URI variable.
Is there a different syntax for the hostname in a Windows container?
** edit **
I'm not able to ping outside the network, from either container:
c:\app> ping 8.8.8.8
Request timed out.
Not sure if this is relevant.

Answer 1

Regardless of container OS, to my knowledge, referring to the other name (db0) directly won't directly work inside the container, but is simply exposed to the other compose entries
Instead, set an env var dependent on the name and read it in the container
environment:
- "ADDRESS_DB=db0"
Then, if you want to be able to ping db0 or similar, have a script set the env var as an available host name on start
Alternatively, you may have success setting it the extra_hosts field, but I haven't tested this and you may need to give it a different name to prevent interpolation
extra_hosts:
- db_url:db0