Docker Swarm
What is a Docker Swarm?
A Docker Swarm is a group of either physical or virtual machines that are running the Docker application and that have been configured to join together in a cluster. Once a group of machines have been clustered together, you can still run the Docker commands that you're used to, but they will now be carried out by the machines in your cluster. The activities of the cluster are controlled by a swarm manager, and machines that have joined the cluster are referred to as nodes.
Docker swarm is a container orchestration tool, meaning that it allows the user to manage multiple containers deployed across multiple host machines.
docker swarm commands
1. Node management
Initialize a swarm: docker swarm init
List swarm nodes: docker node ls
Get the command for new nodes to join a swarm: docker swarm join-token worker or docker swarm join-token worker. The command prints the required command and token: E.g. To add a worker to this swarm, run the following command:
docker swarm join \
--token SWMTKN-1-49nj1cmql0jkz5s954yi3oex3nedyz0fb0xx14ie39trti4wxv-8vxv8rssmk743ojnwacrr2e7c \
192.0.0.10:2377
Check service manger reachability: docker node inspect manager-node-name --format "{{ .ManagerStatus.Reachability }}"
Check node state: docker node inspect node-name --format "{{ .Status.State }}"
Put a node in maintenance mode: docker node update --availability drain node_name
Activate a node (after maintenance): docker node update --availability active node_name
Add a label: docker node update --label-add key=value node_name
Remove a label: docker node update --label-rm key node_name
Search label: docker node inspect node_name | grep Labels -C5
2. Service management
List services (manager node): docker service ls
Describe services (manager node): docker service ps service_name
Inspect a service: docker service inspect service_name
Scale a service: docker service scale service_name=N
Remove service: docker service rm service_name
3. Stack management
Deploy stack from docker-compose file: docker stack deploy -c docker-compose.yml stack_name
List stacks: docker stack ls
List stack services: docker stack services stack_name
List stack tasks: docker stack ps stack_name
Remove stack : docker stack rm stack_name
4. Network management
List networks: docker network ls
Create overlay network: docker network create -d overlay network_name
Remove network: docker network rm network_name
5. Monitor services
Docker stats: docker stats
Service logs: docker service logs service_name
Collect all container logs:
docker service create --mode global --name st-logagent \
--restart-condition any \
--mount type=bind,src=/var/run/docker.sock,dst=/var/run/docker.sock \
-e LOGS_TOKEN=YourLogsToken \
sematext/logagent:latest
Describe services (manager node): docker service ps service_name
Inspect a service: docker service inspect service_name
Scale a service: docker service scale service_name=N
Remove service: docker service rm service_name
List stacks: docker stack ls
List stack services: docker stack services stack_name
List stack tasks: docker stack ps stack_name
Remove stack : docker stack rm stack_name
Create overlay network: docker network create -d overlay network_name
Remove network: docker network rm network_name
Service logs: docker service logs service_name
Collect all container logs:
docker service create --mode global --name st-logagent \
--restart-condition any \
--mount type=bind,src=/var/run/docker.sock,dst=/var/run/docker.sock \
-e LOGS_TOKEN=YourLogsToken \
sematext/logagent:latest