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Docker Swarm Cluster Installation

Introduction

This document describes how to spin up a multi-host Docker swarm cluster built on a VXLAN overlay network in AWS, where a host is a AWS instance and multiple hosts may reside in the same VPC or different VPCs. If there is underlying network connectivity to connect VPCs securely (such as using Aviatrix encrypted peering), a swarm cluster can span across multiple VPCs and to Azure and Google.

For a reference design on how to use Aviatrix OpenVPN® capability to remotely access containers in a swarm cluster in the same manner as accessing instances from your laptop, for example, being able to use “curl” to a container running a web service, check out this link.

To build a Swarm cluster, there needs to be a manager instance, a consul instance, and a few hosting instances. To simplify the topology, manager and consul are combined into one instance.

There are many How to resources online on creating a swarm cluster with a VXLAN overlay network, the guide below is intended to be a reference.

Installation Steps

1. Create one manager/consul instance and few container hosting instances.

At AWS console, launch instances by using Amazon Linux AMI with Docker package, as shown below:

image0

2. Install docker daemon

  For each of the above instances, do the following:
a. ssh into each instance
b. sudo yum update
c. curl -sSL https://get.docker.com/ | sh
d. sudo service docker start
e. sudo service docker stop
f. sudo docker daemon -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock&
g. sudo usermod -aG docker ec2-user
h. logout

3. Start manager/consul

  On the manager/consul instance:
a. ssh into the manager/consul instance
b. ifconfig eth0 (to get the consul’s eth0 IP address, for example, 172.31.12.28)
c. sudo docker run -d -p 8500:8500 --name=consul progrium/consul -server -bootstrap
d. docker run -d -p 4000:4000 swarm manage -H :4000 --replication --advertise 172.31.12.28:4000 consul://172.31.12.28:8500

4. Setup Docker configuration file

  On each container hosting instance:
a. ssh into each instance
b. Follow the same procedures as described in Step 2 to install docker daemon
c. sudo vi /etc/sysconfig/docker and add the following line:
 OPTIONS="--default-ulimit nofile=1024:4096 -H tcp://0.0.0.0:2375 -H unix:///var/run/docker.sock --cluster-advertise eth0:2375 --cluster-store consul://172.31.12.28:8500"
d. sudo service docker restart

5. Join swarm cluster

  On each container hosting instance:
a. ssh into each instance
b. Use “ifconfig eth0” to get container hosting instance’s own IP address, e.g. 172.31.14.64
   Tell consul my IP address and to join the swarm cluster:
   *sudo docker run -d swarm join --advertise=172.31.14.64:2375 consul://172.31.12.28:8500*

6. Create a VXLAN overlay network

On the manager/counsul instance:

  a. ssh into each instance
  b. Create an overlay network “my-overlay-network” with network CIDR “10.0.0.0/24”: docker -H :4000 network create - -subnet=10.0.0.0/24 my-overlay-network
  c. To list the network and you will see the newly created “my-overlay-network” on each hosting instance joined the swarm cluster
     *docker network ls*

7. Launch a container

On each container hosting instance:

  a. ssh into the host
  b. Launch a container “test01” within the overlay network “my-overlay-network:
     *sudo docker run -itd --net my-overlay-network --name test01 ubuntu /bin/bash*
  c. Find out the overlay IP address for container “test01” assigned by consul. There are at least three ways:

  1. type command on the instance:

    sudo docker inspect test01

    The above command returns a json output, look for “IPAddress” under my-overlay-network.

  2. Type command on the instance:

    docker network inspect my-overlay-network, where my-overlay-network is the overlay network name.

  3. Alternatively, use the following command to find out overlay IP address:

    docker inspect -f '{{.Name}} - {{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' test01

    where test01 is the container name.

8. Install Optional Tools (just for fun)

  1. Access into the container and install some network tools if you like:

      *sudo docker exec -ti test01 /bin/bash*
      *apt-get update --yes*
      *apt-get install net-tools --yes*
      *apt-get install iputils-ping –yes*

  2. If you like to have ssh access to your container, follow these steps:

     *apt-get install openssh-server*
     *apt-get install vim*
     *sudo vi /etc/ssh/sshd_config*
       and modify the following 2 lines to:
     *PermitRootLogin yes*
     *#StrictModes yes*
     Setup root password by typing command “passwd”
     *Sudo service ssh restart*
     *ifconfig eth0* to get the IP address
  3. In the container, do “ping 10.0.0.x” to other containers you

    created.

9. To add more container hosting instances, repeat steps 1, 2, 4, 5 and 7.

Note:

You may need to modify “Security Group” of each instance and manager to allow the access to their ports.

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