Keycloak in docker-compose network - docker-compose

Question

I want to setup a Docker network that contains a keycloak, postgres, and webapp instances.
Is there a way to have network communications between containers but also understand oidc client redirects as well? I am having an issue where containers can talk to each other just fine if i setup OIDC with container names for the docker network, but then I run into issues with the client that cannot connect to the those same URLs outside of the docker network on the host machine.
Can anyone point me to the right docker documentation to look at for possible solutions with DNS or host to container communication?
---- EDIT ----
To clarify. The containers can talk to each other just fine under their container names, but the client (i.e., Chrome) has to use localhost to talk to everything. In my setup for my OIDC connection in the ui web application I have to use container names or localhost. How do I get my client to understand container names in order to make the right request?
version: '2'
services:
ui:
container_name: 'ui'
image: 'bdparrish/ui:0.1'
build:
context: .
dockerfile: ./ui/Dockerfile
ports:
- "8085:80"
depends_on:
- "postgres"
- "keycloak"
networks:
- auth-network
environment:
- ASPNETCORE_ENVIRONMENT=Docker
postgres:
container_name: postgres
image: 'postgres'
environment:
POSTGRES_PASSWORD: password
ports:
- "5432:5432"
networks:
- auth-network
keycloak:
container_name: keycloak
image: jboss/keycloak
ports:
- "8080:8080"
depends_on:
- postgres
environment:
DB_VENDOR: "POSTGRES"
DB_ADDR: postgres
DB_PORT: 5432
DB_USER: keycloak
DB_PASSWORD: password
KEYCLOAK_USER: admin
KEYCLOAK_PASSWORD: password
restart: always
networks:
- auth-network
networks:
auth-network:
driver: bridge

Answer 1

You don't have to modify the etc/hosts file.
There is an environment variable for keycloak named KEYCLOAK_FRONTEND_URL especial for this purpose.
Edit your docker compose file to look like this:
version: '2'
services:
ui:
container_name: 'ui'
image: 'bdparrish/ui:0.1'
build:
context: .
dockerfile: ./ui/Dockerfile
ports:
- "8085:80"
depends_on:
- "postgres"
- "keycloak"
networks:
- auth-network
environment:
- ASPNETCORE_ENVIRONMENT=Docker
postgres:
container_name: postgres
image: 'postgres'
environment:
POSTGRES_PASSWORD: password
ports:
- "5432:5432"
networks:
- auth-network
keycloak:
container_name: keycloak
image: jboss/keycloak
ports:
- "8080:8080"
depends_on:
- postgres
environment:
DB_VENDOR: "POSTGRES"
DB_ADDR: postgres
DB_PORT: 5432
DB_USER: keycloak
DB_PASSWORD: password
KEYCLOAK_USER: admin
KEYCLOAK_PASSWORD: password
KEYCLOAK_FRONTEND_URL: http://localhost:8080/auth
restart: always
networks:
- auth-network
networks:
auth-network:
driver: bridge
Then the login should be redirected to that url.

Answer 2

All you need to do is add an entry to your hosts file:
Windows: C:\Windows\System32\drivers\etc\hosts
Linux: /etc/hosts
Append this to the end of the file:
127.0.0.1 keycloak
Then use keycloak:8080 from your UI to talk to your keycloak server instead of localhost:8080. You can still use localhost:8580 to visit the UI in the browser.