Docker/C3/Docker-Swarm/English

Visual Cue	Narration
Show slide: Title Slide	Hello and welcome to the Spoken Tutorial on “Docker Swarm”.
Show Slide: Learning Objectives	In this tutorial, we will learn about Docker Swarm Sharing files using Network File System
Show Slide: System Requirements	To record this tutorial, I am using Ubuntu Linux OS version 22.04 and Docker version 27.0.2
Show Slide: Pre-requisites https://spoken-tutorial.org/	To follow this tutorial, You must have basic knowledge of using Linux terminal For pre-requisite Linux tutorials, please visit this website.
Slide: Docker-machine installation	Docker-machine installation Refer to the Additional Reading material of this tutorial. Follow the steps given in the document to install docker-machine. Docker-machine installation is required to proceed further. Docker-machine simplifies setting up and managing Docker Swarm.
Show Slide: Docker Swarm	Docker Swarm is a container orchestration tool. It allows you to manage a cluster of Docker nodes as a single system. It provides tools to deploy, manage, and scale containerized applications.
Only narration	Let us see the execution of it.
Open terminal	Open the terminal. First let us create a Docker swarm cluster. Type docker swarm init and press Enter.
Highlight Swarm initialised row	We can see that the swarm is initialised and made the current node as manager. Managers manage the swarm cluster.
Highlight To add a worker section	It gives us the swarm join command to add worker nodes to the swarm. It has token id and manager IP as parameters. The values may be different for you according to system configuration. Now copy the command. We can use this while joining the swarm.
Only narration	First let us create a worker node. Workers run containers and execute tasks assigned by managers.
Type docker run -d --privileged --name	Enter the command as shown. The docker run command creates a Docker-in-Docker worker container.
Highlight the output	docker dind image is pulled and downloaded in our local system.
Type docker exec -it worker and paste	Now we will join the worker node to the swarm cluster. Type the command as shown and paste the copied command and press Enter.
Highlight the output	We can see a message that our worker node have joined the swarm.
Type docker node ls and press Enter	Now let us see the list of all the nodes in the swarm. Type docker node ls and press Enter.
Highlight the output	We can see two nodes. One is the leader i.e manager and other is the worker node which we created now.
Only narration	Now let us see how to deploy services in a swarm cluster through an example.
	In the terminal, enter the command as shown. It creates the myExample service using the stuser1/node-express image. Services are tasks that run containerized applications. We will use the previously created image stuser1/node-express for this example.
Highlight --publish 3000:3000	It maps port 3000 of the container to port 3000 on the host.
Press Enter	Now press Enter.
Highlight the output	The output confirms the service has deployed successfully.
Type docker service ls and press Enter	Let us verify by retrieving the list of services. Enter the command as shown.
Highlight myExample row.	We can see our service myExample in the list. Here replicas indicate the number of tasks in the service. For now we only have 1 task running.
Only narration	Let us see how to update the service.
	Type the command as shown. The docker service update command changes the image used by the service. Here, we’re switching to the nginx image which may not be present in the local system. It will automatically pull the nginx image from Docker Hub and use it. Press Enter.
Highlight the output	We can see that the service is updated successfully.
Type docker service ls	Enter the command as shown to get the services list.
Highlight myExample row	We can see that the image is updated to nginx.
Type docker service rollback myExample	To roll back to the previous image, enter the command as shown.
Highlight the output	We can see that the rollback is completed.
Type docker service ls and press Enter	Now verify by using docker service ls command.
Highlight the output	We can see that the image is updated back to stuser1/node-express.
Only narration	Now let us see how to scale the service.
Type docker service scale myExample=2	Enter the command as shown. This command adjusts myExample to run 2 replicas. This means there will be two instances of myExample running in the Swarm. It will be useful when we need backup or replicated tasks. It will take some time for the system to find the image and use it.
Highlight the output	We can see that now our service myExample has successfully converged to running 2 tasks.
Only narration	To scale down, just decrease the number of replicas in the previous command.
Type docker service ps myExample	To get the history of the service, enter the command as shown.
Highlight the running processes	We can see that 2 processes are running. The processes that are shown as shutdown are previously executed. Rejected processes are system glitches while searching for images.
Type docker service rm myExample	To remove the service, enter the command as shown.
Type docker service ls	Again we will get the list to verify. We can see our service myExample is removed from the list.
Only narration	Now let us see how to share files using NFS.
Show Slide: Share files using NFS	Network File System (NFS) allows file sharing between nodes in a Swarm setup. This setup provides shared, persistent storage for distributed applications. NFS is ideal for storing files needed by multiple services or replicas. It ensures data consistency and simplifies data management across nodes.
Only narration	Let us see the execution of it.
Type mkdir -p /srv/nfs/sharefiles	First we will create a directory for files’ storage. Type the command as shown. The -p flag ensures all required parent directories are created if it is not there.
	Next we will change the ownership. Type the command as shown. This command changes ownership to nobody user and nogroup. Enter the password if prompted.
Type sudo chmod 777 /srv/nfs/sharefiles	Type the command to give read, write and execute permissions to all users. This makes the directory accessible to every user across nodes.
Type sudo apt-get install -y nfs-kernel-server	Then we need to install an nfs-kernel-server for NFS support on the manager. For that, enter the command as shown. The -y option automatically confirms the installation prompt.
Type sudo nano /etc/exports	Then enter the command as shown. This opens the exports file to define directories for sharing.
	We’ll add our directory to the file for NFS access using this command.
Highlight rw	rw shares the directory with read and write access.
Highlight sync	sync ensures data consistency.
Only narration	Then save by pressing Ctrl+S and exit by pressing Ctrl+X.
Type sudo exportfs -a	Then enter the command as shown. This shares all directories in the exports file for NFS access.
	Then we shall restart the NFS server to apply new configuration settings. For that enter the command as shown.
	Let us open an interactive shell in the worker container. Enter the command as shown.
Type apk add --no-cache nfs-utils	In the interactive shell, type the command as shown. This instals NFS utilities, which enable NFS client functionality.
Type mkdir -p /mnt/nfs/sharefiles	Let us create a local directory on the worker for mounting NFS share. Enter the command as shown. The -p flag ensures that all necessary parent directories are created.
	Then type the command as shown. This mounts the manager’s NFS directory to the worker’s local directory.
Highlight 10.0.2.15	This is the manager node’s IP address. Replace it with your manager node’s IP address.
Highlight nolock	nolock option disables file locking for simpler setup in basic configurations.
	Type df -h | grep nfs and press Enter	To verify the mount, enter the command as shown.
Highlight the output	We get details of mounted filesystems, filtered for our NFS mount. We can see our mounted sharefiles.
Type exit and press Enter	To go back to the manager node, enter the exit command.
Only narration	Now we have set up the basic configurations for file sharing in the worker node. Let us create a file testfile dot txt for sharing purposes in the manager node.
	Enter the command as shown. This creates a testfile in the shared directory with the given text in it.
Type docker exec -it worker sh	Again let us open an interactive shell in the worker node with this command.
	Enter the command as shown. This reads the file from the worker node to verify shared file access of the manager node.
Highlight the output	We can see the text from the testfile indicating successful sharing of files.
Type docker swarm leave	To leave the swarm cluster, type docker swarm leave and press Enter.
Highlight the output	We can see that the worker node has left the swarm.
Type exit and press Enter	To go back to the manager node, enter the exit command.
Type docker swarm leave --force	To exit the swarm cluster from the manager node, enter the command as shown. Here we are extending the swarm leave command with hyphen hyphen force.
Highlight the output	We can see that the manager node has left the swarm.
Show Slide: Summary	This brings us to the end of this tutorial. Let us summarise. In this tutorial, we have learnt about Docker Swarm Sharing files using Network File System
Show Slide: Assignment	As an assignment, please do the following Scale myExample to 5 replicas
Show Slide: Assignment Observation	myExample is upscaled to 5 replicas.
Show Slide: About Spoken Tutorial project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
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Show Slide: FOSSEE Forum	For any general or technical questions on Docker, visit the FOSSEE forum and post your question.
Show slide: Acknowledgement	Spoken Tutorial Project was established by the Ministry of Education, Government of India.
Slide: Thank you	This is Pranjal Mahajan, a FOSSEE Semester Long Intern 2024, IIT Bombay signing off Thanks for joining.

Contributors and Content Editors

Madhurig, Nirmala Venkat