DevOps Playground 3 - Hands on Docker Swarm

Mining bitcoins using everyone's laptops with Docker Swarm

Pre-requisites

1. Download Vagrant and Virtualbox and install them.
2. If you are running Windows, install Git Bash
3. Open ports 2375, 4000 and 8500 or disable firewall
4. Change the hostname in the Vagrantfile, line 4, check that your hostname is unique

Start and configure the VM

Start the vagrant machine, which is going to download and configure everything. In the folder where your Vagrantfile is:
vagrant up

On the Docker Swarm manager, create the consul server and the swarm manager

6. Create a consul server (Only on the manager)
   docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap
7. Start the swarm manager (Only on the manager)
   docker run -d -p 4000:4000 swarm manage -H :4000 --advertise <manager-ip>:4000 consul://<manager-ip>:8500

Connect to the VM and join the Docker Swarm

1. Connect to the vagrant machine through SSH
   vagrant ssh
2. Start the swarm clients
   docker run -d swarm join --advertise=<your-vm-ip>:2375 consul://<manager-ip>:8500

On the Docker Swarm manager, start the miners

1. Start one miner
   docker -H :4000 run -d kourkis/miner
2. To remove all of the miners
   docker -H :4000 ps -q | xargs docker -H :40bbbb00 rm -f
3. To create several miners in a single command
   for i in {1..5}; do docker -H :4000 run -d kourkis/miner; done

Remote API

​Most Docker API endpoints are implemented by Swarm, meaning that tools built on top of it will work out of the box, including the Docker CLI. Visit the API documentation to get more details. ​

To enable the Remote Api Access to a Docker Host:

There is no need to do it during this meetup, as this is taken care of in the Vagrantfile. This is simply for your information.

• Without security: For the purpose of the Meetup we open the socket to everyone and don't use TLS for securing the Remote API Access. Add -H tcp://<ip>:<port> to the DOCKER_OPTS in /etc/default/docker.
  Reference
• With security: For securing it see this documentation. ​

Using the Remote API

The following GET commands can be run from your web browser.

Get running containers on the Docker Swarm cluster

​ http://<manager-ip>:<port>/containers/json

• <manager-ip> - The Docker Swarm manager IP. Docker Swarm Manager IP to access containers in the cluster level.
• <port> - The Docker Swarm Manager listening port. ​
• (Alternative) From the command line, we execute the following command
  curl -X GET http://<manager-ip>:<port>/containers/json ​

Get a specific Container information

​ http://<manager-ip>:<port>/containers/<container-id or container-name>/json ​

• <manager-ip> - The Docker Swarm manager IP. Docker Swarm Manager IP to access containers in the cluster level.
• <port> - The Docker Swarm Manager listening port. ​
• (Alternative) From the command line, we execute the following command
  curl -X GET http://<manager-ip>:<port>/containers/<container-id or container-name>/json ​

Get logs from a specific Container ID

http://<docker-node-ip>:<open-port>/containers/<container-id or container-name>/logs?stderr=1&stdout=1&

• Include the logs keyword after the container id/name
• stdout – 1/True/true or 0/False/false, show stdout log. Default false.
• stderr – 1/True/true or 0/False/false, show stderr log. Default false. ​
• (Alternative) From the command line, we execute the following command
  curl -X GET http://<manager-ip>:<port>/containers/<container-id or container-name>/logs?stderr=1&stdout=1& ​

Example: Running container and inspecting it

What the docker run command would normally do, is to create a container and then start it. In this example you are going to create a hello-world container, then start it and finally check info about it (including the status, node name, etc). Ensure you replace the fields between < and > with the correct information.

1. Create the hello-world container:
   curl -H "Content-Type: application/json" -X POST -d '{"Hostname": "hello-world-node", "Image": "hello-world"}' http://<manager-ip>:<port>/containers/create?name=<container-name> ​
2. Start the hello-wold container by its name:
   curl -X POST -H "Content-Type: application/json" -d '{}' http://<manager-ip>:<port>containers/<container-name>/start ​
3. Query your node by its name:
   curl -X GET http://<manager-ip>:<port>/containers/<container-name>/json

Useful commands

• List images in the docker host
  docker images
• Run an image in a container
  docker run <image-name>
• Get the containers running on your host at the moment, with the -a option to see stopped containers too
  docker ps [-a]
• Stop a container using its id
  docker stop <container-id>
• Remove a container, with the -f option to force the container to stop if it is running
  docker rm [-f] <container-id>
• Print the logs of the container
  docker logs <container-id>
• Attach to a container
  docker attach <container-id>

What is next

• Add TLS authentication for Security
• Define Affinity rules. This is useful to for example to guarantee two highly resource consuming containers don’t get scheduled on the same machine

Removing the environment

1. Exit from the VM
2. Execute vagrant destroy from the same directory we have been working on.