Docker compose can't access ports of other containers - docker

Question

I have 2 containers running with docker compose. One of the containers is executing a shell script which should check if the other container has already started and is running on port 9990.
Even though the container is starting, the shell script echos nothing.
keycloak:
image: jboss/keycloak:latest
volumes:
- ./imports/cache_reload/disable-theme-cache.cli:/opt/jboss/startup-scripts/disable-theme-cache.cli
- ./imports/themes/custom/:/opt/jboss/keycloak/themes/custom-theme/
- ./imports/realm/realm-export.json:/opt/jboss/realms/custom-import.json
environment:
DB_VENDOR: MYSQL
DB_ADDR: mysql
DB_DATABASE: keycloak
DB_USER: keycloak
DB_PASSWORD: password
KEYCLOAK_USER: admin
KEYCLOAK_PASSWORD: Pa55w0rd
ports:
- 8080:8080
depends_on:
- mysql
keycloak_installer:
image: solr:6.6-alpine
volumes:
- ./imports/scripts/import-realm.sh:/docker-entrypoint-initdb.d/init.sh
depends_on:
- keycloak
The shell script is the following:
echo "MOIN LEUDE TRYMACS HIER!"
while ! nc -z localhost 9990; do
sleep 1
echo "Waiting for keycloak server startup 9990..."
echo "$(nc -z localhost 9990)"
done
The first echo is printed, but then nothing else is printed.
The container keycloak is running on Port 9990.
Please help, thanks

Answer 1

You have to understand more detail about network in docker compose.
To solve your issue, you need :
Add network in your docker compose file for each container (there is a default network but to understand the mechanism, you can define it explicitly). This must looks like this (under ports for example) for the first container (named keycloak):
ports:
- 8080:8080
networks:
- keycloak_network
On the second container (named keycloak_installer) (you must expose the port that you want to request in the first container):
depends_on:
- keycloak
networks:
- keycloak_network
On your script call explictly the second container which will be now available by the network. You must change your code by this :
nc -z keycloak_installer 9990