Swarm mode
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This document discusses Docker Swarm Mode, which allows managing a cluster of Docker Engines called a swarm. Key features include integrated cluster management, declarative application deployment across nodes, automatic scaling, service discovery, and encryption between nodes. The document demonstrates initializing a swarm on two VMs, adding a worker node, deploying services in replicated and global modes, attaching services to networks, publishing service ports, updating services, and more swarm commands.
Swarm mode
- 1. Docker Swarm Mode Dharmit Shah @dharm1t
- 2. Who am I? ● Software Engineer @ Red Hat; developing developer tools ● Co-organizer of Docker and Ansible meetups ● Work on CentOS, Docker, Ansible, Vagrant, etc. ● Love vim, zsh, i3wm, and all things CLI ● dharmit on GitHub dharm1t on Twitter
- 3. What is Swarm Mode? ● A mode built into Docker Engine ● Available with Docker 1.12 or later ● Lets you manage a cluster of Docker Engines ● Cluster of Docker Engines is called a swarm ● Use the familiar Docker CLI to create a swarm, deploy application services to a swarm, and manage swarm behavior. ● Swarm Mode != Swarm Kit
- 4. Features ● Cluster management integrated with Docker Engine ● Can deploy Manager/Worker node using Docker Engine ● Declarative model to describe entire application stack ● Scale up or down based on requirements ● Constantly monitors and reconciles the cluster state ● Built in service discovery ● TLS auth and encryption for secure communication
- 5. Hands-on
- 6. My Setup ● 2 VMs running on DigitalOcean ● 1 will run as manager ● 1 will run as worker ● Add 1 VM to work as manager
- 7. Initialize a Swarm $ docker swarm init ● This command will initialize a swarm ● Docker Engine targeted by this command becomes a manager in the newly created single-node swarm ● Generates two random tokens - manager and worker tokens ● Use proper token to make a node join as worker or manager
- 8. Add a node to Swarm $ docker swarm join --token <random-token-generated-by-previous-command> <ip-port-of-manager> This command will add a node to a Swarm as worker node $ docker swarm join-token manager This command will add a manager node to Swarm
- 9. Create services $ docker service create --name redis redis:3.0.6 Creates a service named redis $ docker service create --name redis --replicas=5 redis:3.0.6 Creates a service redis with 5 replicas across the swarm $ docker service ls Lists the services in the cluster
- 10. Replicated mode & Global mode $ docker service create --name redis --replicas=5 redis:3.0.6 Creates a service redis with 5 replicas across the swarm $ docker service create --name redis --mode global redis:3.0.6 Creates a global service with 1 container on each node
- 11. Attach service to network $ docker network create --driver overlay my-network $ docker service create --replicas 3 --network my-network --name my-web nginx $ docker service ls Containers on the same network can access each other using service discovery
- 12. Publish Service Ports $ docker service create --name my_web --replicas 3 --publish 8080:80 nginx Makes service accessible on port 8080 of every node regardless if there is a container running for that service on the node!
- 13. Swarm Inspect $ docker service inspect nginx ● Provides JSON output ● Same as docker inspect for containers ● Should be run only on manager nodes
- 14. Swarm Update ● Update an existing service $ docker service update --publish-add 6379:6379 redis Publishes redis service to port 6379 on all nodes in Swarm $ docker service update --image redis:latest redis Let’s watch the output of “$ docker service ps redis” Has many, many more options! Refer the docs.
- 15. Scale a service $ docker service create --name redis redis:3.0.6 Creates a single container on a random node in the Swarm $ docker service scale redis=2 Starts another container on a random node
- 16. ps, ls, rm, ● ps ○ List the tasks of a service ● ls ○ Lists the services in the swarm ● rm ○ Removes a service from the swarm
- 17. References ● https://docs.docker.com ● Slideshare by Mike Goelzer and Andrea Luzzardi ● Docker Community Repo ● And some tinkering with containers…
- 18. Thank you!