Complete the setup of a swarm mode cluster with managers and worker nodes
- Run on the master:
docker swarm init --advertise-addr <MANAGER-IP> - Verify swarm mode by:
docker info - Verify node status by:
docker node ls
State the differences between running a container vs running a service
- Running container is Docker in single engine mode
- Running a service is when Docker is running in swarm mode
Demonstrate steps to lock a swarm cluster
- To initialize a swarm from rebooting master nodes:
docker swarm init --autolock - To enable autolock:
docker swarm update --autolock=true - To disable autolock:
docker swarm update --autolock=false - To unlock a swarm:
docker swarm unlock - View current key:
docker swarm unlock-key - Rotate current key:
docker swarm unlock-key --rotate
Extend the instructions to run individual containers into running services under swarm
- To create a new service:
docker service create --replicas 1 --name helloworld alpine ping docker.com- The
docker service createcommand creates the service. - The
--nameflag names the servicehelloworld. - The
--replicasflag specifies the desired state of 1 running instance. - The arguments
alpine ping docker.comdefine the service as an Alpine Linux container that executes the commandping docker.com.
- The
- To view current services running:
docker service ls
Interpret the output of docker inspect commands
- To get a list of services:
docker service ps - To inspect a service:
docker service inspect <SERVICE-ID> - Consider viewing the yaml output:
docker service inspect --pretty <SERVICE-ID>
Convert an application deployment into a stack file using a YAML compose file with docker stack deploy
- Command usage:
docker stack deploy [OPTIONS] STACK - Example:
docker stack deploy --compose-file docker-compose.yml vossibility
TODO: Read more about Docker Stack
Manipulate a running stack of services
- To list docker stack services:
docker stack ls - Available Stack commands: deploy, ls(stacks), ps(tasks), rm, services
TODO: Read more about Docker Stack
Increase number of replicas
- To update existing service:
docker service update --replicas=NUMBER SERVICE - To update existing service:
docker service scale SERVICE=NUMBER - To update existing service:
docker service scale SERVICE1=NUMBER SERVICE2=NUMBER - To view number of replicas:
docker service ls
Add networks publish ports
- Create a service:
docker service create nginx && docker service ls docker service create --name helloworld alpine ping docker.com- Update the service:
docker service update --publish-add 80 nginx - To publish a service's ports externally:
docker service create --publish 8080:80 nginx - Usage:
--publish <TARGET-PORT>:<SERVICE-PORT>
Mount volumes
$ docker service create \
--mount src=<VOLUME-NAME>,dst=<CONTAINER-PATH> \
--name myservice \
<IMAGE>Illustrate running a replicated vs global service
- To inspect current mode:
docker service inspect SERVICE --pretty | grep "Service Mode" - A replicated service is replicated to the replicas number
- A global service runs on all available nodes
Identify the steps needed to troubleshoot a service not deploying
docker service lsdocker service ps SERVICEdocker service insect SERVICEdocker logs CONTAINER- To prevent a service from being deployed, scale the service to 0
Apply node labels to demonstrate placement of tasks
- Add metadata to a swarm node using node labels
docker node update --label-add foo worker1- When you create a service, you can use node labels as a constraint. A constraint limits the nodes where the scheduler deploys tasks for a service
Sketch how a Dockerized application communicates with legacy systems
- donno...
Paraphrase the importance of quorum in a swarm cluster
- Always have more than two managers
- Odd number of managers is recommended
- To add new nodes:
docker swarm join-token (worker|manager)
Demonstrate the usage of templates with docker service create
- Templated configs can be used in: --hostname, --mount, --env
- Example:
docker service create --name hosttempl \ --hostname="{{.Node.Hostname}}-{{.Node.ID}}-{{.Service.Name}}" busybox top