Docker ABC
Intoduction to Docker
Docker Compose
To create multi-container application (Stack). It allows you to compose multiple services (containing a docker image) in a single file.
A compose file can consist of multiple services (containing a docker image).
All services within a compose file will join the same "network".
By default, the name of the service within the compose file will be the host name of that container within the same network. E.g in following compose file:
services:
db:
image: ...
application:
image: ...
the host name of the database from within the application container will be "db".
LIMITATION: docker compose file will only run on one single machine. (Use docker swarm for that purpose). However, the compose file can be used to run on a swarm.
Introduction to Docker Swarm
Swarm
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Node1 Node n
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Stack1 Stack n
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Service1 Service n Service 1 Service n
Terminology
Swarm: One or more nodes
Node: Physical or virtual machine running a docker engine in swarm mode
Stack: Group of services
Service: Group of containers of the same image
Task: is started by a service and executes the actual container
Scale: Once you have deployed a service to a swarm, you are ready to use the Docker CLI to scale the number of containers in the service