{"id":163,"date":"2020-09-26T12:40:47","date_gmt":"2020-09-26T12:40:47","guid":{"rendered":"https:\/\/dft.wiki\/?p=163"},"modified":"2026-06-09T15:12:19","modified_gmt":"2026-06-09T19:12:19","slug":"how-to-use-docker","status":"publish","type":"post","link":"https:\/\/dft.wiki\/?p=163","title":{"rendered":"How to Use Docker and Docker Swarm"},"content":{"rendered":"

Docker is by far the most popular application container solution, and Docker Swarm is an integrated functionality of Docker Engine that orchestrates a group of Docker engines into a single virtual Docker engine. It provides high availability and aggregated computing power across the cluster.<\/p>\n

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DOCKER INSTALLATION<\/strong><\/p>\n

sudo apt update && sudo apt upgrade -y\r\nsudo apt install docker.io -y<\/pre>\n
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DOCKER SWARM SETUP<\/strong><\/p>\n
On the node you want to be the manager of the cluster, initialise Swarm:<\/p>\n
sudo docker swarm init<\/pre>\n
Copy and paste the generated command on all other nodes to join the cluster as workers. It will look like this:<\/p>\n
sudo docker swarm join --token ************************************************************* 192.168.10.10:2377<\/pre>\n
Check all the nodes of the cluster:<\/p>\n
sudo docker node ls<\/pre>\n
In the future, to add more worker nodes to the cluster, issue the following command from the current manager node to get the join command again:<\/p>\n
sudo docker join-token worker<\/pre>\n
Or for an additional manager node:<\/p>\n
sudo docker join-token manager<\/pre>\n
To remove a node from the cluster:<\/p>\n
sudo docker swarm leave<\/pre>\n
OR<\/p>\n
sudo docker node rm ****************** --force<\/pre>\n
To promote (or demote) a standby manager to the current leader:<\/p>\n
sudo docker node promote ******************<\/pre>\n
To make a node unavailable for running workloads:<\/p>\n
sudo docker node update --availability drain<\/pre>\n
Or to make it available again:<\/p>\n
sudo docker node update --availability active<\/pre>\n
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DOCKER BASIC COMMANDS<\/strong><\/p>\n
Note there are no images pulled yet (“pull” is the term used to download and extract images):<\/p>\n
sudo docker images<\/pre>\n
For this exercise we will use Debian, but you can choose Ubuntu, for example:<\/p>\n
sudo docker pull debian<\/pre>\n
OR<\/p>\n
sudo docker pull ubuntu<\/pre>\n
Since no version was specified, the latest released version will be chosen: Downloaded newer image for debian:latest<\/strong><\/em><\/p>\n
Now, if you check the images, ‘debian:latest’ will be listed:<\/p>\n
sudo docker images<\/pre>\n
Many containers can be created from the same image. None of them will modify the image content, but all will use it simultaneously (like a read-only file).<\/p>\n
Web Server Example<\/strong><\/p>\n
sudo docker run --name html -d -it -p 80:80 -v ~\/html:\/var\/www\/html debian:latest \/bin\/bash<\/pre>\n
Description of the syntax:<\/p>\n