Docker Swarm Contd
- Each Docker Host can be manager or worker
- In Docker Swarm we specify the desired state
- Terminology
- Nodes:
- The instance where docker is installed.
- Two Types
- Manager Node:
- We communicate with Manager to specify our service definitions
- This node will assign unit of work called as tasks to the Worker nodes
- Worker Node:
- They recieve & execute the tasks dispatched from manager node
- An agent runs on the worker node and reports on the tasks assigned to it
- Swarm Setup:
- 3 ubuntu instances and install docker (ensure each instance is atleast 2 vcpus 4 GB of RAM)
- Install Docker on all the three nodes
- On the designated manager node execute
docker swarm init --advertise-addr 172.31.46.65
* Now login into worker nodes and execute docker swarm join command
docker swarm join --token SWMTKN-1-3cwg22o4p780ip3enz9g5ijzqogl1v5s1a89egwcp56j5pkyk1-5baqd98h34xiabjrtmp0oiqxz 172.31.46.65:2377
* Verify The nodes docker node ls in the manager
* verify the networks in the manager and nodes docker network ls
* now lets create service
docker service create --replicas 3 --name apache httpd
* To delete the service execute docker service rm apache
- Now Lets create a docker service and verify the network connectity
- Exercise: Specify how to verify communication between containers on different nodes in swarm
