Docker Compose dependent named container - docker

Question

I am trying to bring up my container using docker compose. This container is dependent on two other containers with names 'rabbitmq' & 'mysqldb'.
What my scenario is that the dependent named containers are already created with said name. This is because of some additional configuration i needed for mysql.
How can I link those two containers to this container using docker-compose. Such that it also starts up my named containers when bringing up this myservice container.
Would appreciate any help or direction.
myservice:
image: myaccount/myservice
ports:
- "8081:8081"
restart: always
depends_on:
- rabbitmq
- mysqldb
environment:
SPRING_DATASOURCE_URL: 'jdbc:mysql://mysqldb:3306/myservice'
SPRING_PROFILES_ACTIVE: 'mysql'
SPRING_RABBITMQ_HOST: 'rabbitmq'
healthcheck:
test: ["CMD", "curl", "-f", "http://192.168.99.100:8081/actuator/health"]
interval: 1m30s
timeout: 10s
retries: 3
UPDATE:
I was able to resolve this using external_links and the default bridge.
version: '3'
myservice:
image: myaccount/myservice
ports:
- "8081:8081"
restart: always
external_links:
- rabbitmq
- mysqldb
network_mode: bridge
environment:
SPRING_DATASOURCE_URL: 'jdbc:mysql://mysqldb:3306/myservice'
SPRING_PROFILES_ACTIVE: 'mysql'
SPRING_RABBITMQ_HOST: 'rabbitmq'
healthcheck:
test: ["CMD", "curl", "-f", "http://192.168.99.100:8081/actuator/health"]
interval: 1m30s
timeout: 10s
retries: 3
Any other alternative is appreciated. Problem is using this approach, the dependent docker containers already need to be running. However, in case the docker containers are down, I want compose to bring the same containers up. Any ideas?

Answer 1

docker-compose up doesn't run already created containers. It creates the containers from an image and the runs them. So I'll make the presumption that you have images (or dockerfiles) already for these containers. However you can use --no-recreate with docker-compose up to re-use already built containers, this could be a workaround if you have a problem with the regular usage.
Under services in your docker-compose.yml you simply need to define a service for your other two images too. Example below.
services:
service1:
image: images/service1image
depends_on:
- service2
- service3
service2:
image: images/service2image
service3:
build: docker/service3
You don't need to define a network as terrywb suggested if you define them this way. docker-compose automatically creates a bridge network for general use and maps ports for all defined services between them. However if you don't define them as a service then you'd likely need to define a network to connect them, of course if you do this then you won't be able to automatically start them up at the same time using docker-compose which is the whole issue you're trying to solve. If you really don't want them as services then I can only suggest you create a "startup.sh" bash/shell file to handle this. As then you'd be trying to do something outside of the functionality scope docker-compose provides.

Answer 2

I believe that you need to define a network in each of your docker-compose files.
networks:
mynet:
Next, add that network to each container definition
myservice:
networks:
- mynet