Docker-swarm across multiple hosts using same docker-compse file - docker

Question

I am building a docker swarm across 3 hosts for the following services, Grakn, Redis, Elasticsearch, MinIO and RabbitMQ.
My queries are this,
Can i use one docker-compose.yml so that everything builds across 3 hosts? Or we need to have 3 docker-compose.yml file?
In order to have HA, I also want to build 3 more host so that say, if one host (physical) fails, the services which are running on this be transfered to other one and service wont be interrupted.
Can i use docker stack here, if so how?
services:
grakn:
image: graknlabs/grakn:1.7.2
ports:
- 48555:48555
volumes:
- grakndata:/grakn-core-all-linux/server/db
restart: always
redis:
image: redis:6.0.5
restart: always
elasticsearch:
image: docker.elastic.co/elasticsearch/elasticsearch:7.8.0
volumes:
- esdata:/usr/share/elasticsearch/data
environment:
- discovery.type=single-node
restart: always
ulimits:
memlock:
soft: -1
hard: -1
nofile:
soft: 65536
hard: 65536
minio:
image: minio/minio:RELEASE.2020-05-16T01-33-21Z
volumes:
- s3data:/data
ports:
- "9000:9000"
environment:
MINIO_ACCESS_KEY: ${MINIO_ACCESS_KEY}
MINIO_SECRET_KEY: ${MINIO_SECRET_KEY}
command: server /data
healthcheck:
test: ["CMD", "curl", "-f", "http://localhost:9000/minio/health/live"]
interval: 30s
timeout: 20s
retries: 3
restart: always
rabbitmq:
image: rabbitmq:3.8-management
environment:
- RABBITMQ_DEFAULT_USER=${RABBITMQ_DEFAULT_USER}
- RABBITMQ_DEFAULT_PASS=${RABBITMQ_DEFAULT_PASS}
restart: always

Answer 1

Can i use one docker-compose.yml so that everything builds across 3
hosts? Or we need to have 3 docker-compose.yml file?
Yes, you should use one docker-compose.yml file. There you declare services and their desired state including number of replicas.
In order to have HA, I also want to build 3 more host so that say, if
one host (physical) fails, the services which are running on this be
transfered to other one and service wont be interrupted.
If you initialized a cluster of Docker Engines in swarm mode and these engines run on different hosts, service replicas can run on any host. (unless you restrict service placement using Docker labels)
Can i use docker stack here, if so how?
Yes, run docker stack deploy --compose-file [Path to a Compose file]