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The following test scenario sets up a Docker Swarm environment with a swarm manager, a discovery backend service and a single Swarm node. For the discovery backend we use 'Consul' which provides the following features:*

Service discovery (interface for register new Swarm nodes; callback method for Swarm managers to react on newly added Swarm nodes; list of registered Swarm nodes)

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Failure detection

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Swarm store (key-value store for persistent the cluster state)

The following diagram visualizes the components and their connections within the test scenario:

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Download & install VirtualBox (https://www.virtualbox.org/)
Download the actual CoreOS image (https://coreos.com/os/docs/latest/booting-with-iso.html)

Create two virtual machines:

Name:	CoreOS <version> - cluster-r730-1	CoreOS <version> - cluster-r730-k20-1
Type:	Linux
Version:	Linux 2.6 / 3.x / 4.x (64-bit)
Memory:	1024MB1024 MB
Storage:	Create new virtual hard disk:
	Name: CoreOS <version> - cluster-r730-1.vdi	CoreOS <version> - cluster-r730-k20-1.vdi
	Size: 8GB (Dynamically expanding sorage)
Network	Adapter 1: NAT

Step 2: Install CoreOS

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Open the settings for the virtual machine 'CoreOS <version> - cluster-r730-1'
Change following settings:
- Network/Adapter 1: Internal Network
  - Name: ias-ssh.ias.u-psud.fr
Run the virtual machine

Set static IP address

Code Block

language	bash
title	Listing 3
linenumbers	true

# setup static IP address
sudo cat > /etc/systemd/network/static.network <<- EOF
sudo vim /etc/systemd/network/static.network
[Match]
Name=enp0s3

[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
EOF
# apply configuration
sudo systemctl restart systemd-networkd

Add entries to the hosts file

Code Block

language	bash
title	Listing 4
linenumbers	true

sudo cat > /etc/hosts <<- EOF
IPAddress        Hostname        Alias
127.0.0.1        localhost        cluster-r730-1
192.168.0.15    cluster-r730-1
192.168.0.16    cluster-r730-k20-1
EOF

Enable TCP socket for docker Daemon for remote access

Code Block

language	bash
title	Listing 5
linenumbers	true

sudo cat > /etc/systemd/system/docker-tcp.socket <<- EOF
[Unit]
Description=Docker Socket for the API

[Socket]
ListenStream=2375
BindIPv6Only=both
Service=docker.service

[Install]
WantedBy=sockets.target
EOF
systemctl enable docker-tcp.socket
systemctl stop docker
systemctl start docker-tcp.socket
systemctl start docker
sudo reboot now

Repeat the above steps for the virtual machine 'CoreOS <version> - cluster-r730-k20-1' (adapt alias for localhost to cluster-r730-k20-1)

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Run the virtual machine 'CoreOS <version> - cluster-r730-1'

Setup the Create test scenario script for the master node

Code Block

language	bash
title	Listing 6
linenumbers	true

sudo cat > ~/docker-swarm-master-consul-demo.sh <<- EOF
#!/bin/bash
# docker-swarm-master-consul-demo.sh

echo This demo script simulates a docker swarm environoment with a consul discovery server and a swarm manager.

echo STEP 1: Clean up existing docker containers.
docker stop consul swarm-master
docker rm -v consul swarm-master

read -n1 -r -p "Press any key to continue..." key

echo STEP 2: Run the consul server as a new docker container.
echo The following ports are published:
echo 8400: RPC \(optional\)
echo 8500: HTTP
echo 8600: DNS \(optional\)
docker
 run -d -p 8400:8400 -p 8500:8500 -p 8600:53/udp --name=consul 
--add-host=cluster-r730-1:192.168.0.15 
--add-host=cluster-r730-k20-1:192.168.0.16 progrium/consul -server 
-bootstrap
docker ps

read -n1 -r -p "Press any keg to continue..." keg

echo STEP 3: Run the swarm manager as a new docker container.
echo         The following ports are published:
echo         4000: RPC
docker
 run -d -p 4000:4000 --name=swarm-master 
--add-host=cluster-r730-1:192.168.0.15 
--add-host=cluster-r730-k20-1:192.168.0.16 swarm manage -H :4000 consul://cluster-r730-1:8500
docker ps

read -n1 -r -p "Press any key to continue..." key

echo STEP 4: Check as port 4000 and 8500 are published.
netstat -npl | grep '4000\|8500'

read -n1 -r -p "Press any key to continue..." key

echo
 STEP 5: Before proceeding: Run the swarm agent on remote server 
\(cluster-r730-k20-1\) by executing the script 
'docker-swarm-node1-consul-demo.sh'.

read -n1 -r -p "Press any key to continue..." key

echo STEP 6: Check as swarm node \(1\) is available over cluster-r730-k20-1:2375.
curl
 -s cluster-r730-k20-1:2375 > /dev/null && echo swarm node 
\(1\) is available || echo ERROR: swarm node \(1\) is not available

echo STEP 7 Enlist all nodes within the cluster.
docker run --rm --add-host=cluster-r730-1:192.168.0.15 --add-host=cluster-r730-k20-1:192.168.0.16 swarm list consul://cluster-r730-1:8500

read -n1 -r -p "Press any key to continue..." key

echo STEP 8: Use regular docker commands on the swarm cluster.
docker -H cluster-r730-1:4000 info

echo End of the script.
EOF

Run the virtual machine 'CoreOS <version> - cluster-r730-k20-1'

Setup the Create test scenario script for the slave node

Code Block

language	bash
title	Listing 7
linenumbers	true

sudo cat > ~/docker-swarm-node1-consul-demo.sh <<- EOF
#!/bin/bash
# docker-swarm-node1-consul-demo.sh

echo This demo script simulates a docker swarm environment with a swarm agent.

echo STEP 1: Clean up existing docker containers.
docker stop swarm-node-1
docker rm -v swarm-node-1

read -n1 -r -p "Press any key to continue..." key

echo
 STEP 2: Before proceeding: Run the consul server and swarm master on 
remote server \(cluster-r730-1\) by executing the script 
'docker-swarm-master-consul-demo.sh'.

read -n1 -r -p "Press any key to continue..." key

echo STEP 3: Check as the consul server and swarm manager are available over cluster-r730-1:[4000,8500].
curl
 -s cluster-r730-1:8500 > /deu/null && echo consul server is 
available || echo ERROR: consul server is not available
curl -s 
cluster-r730-1:4000 > /deu/null && echo swarm master is 
available || echo ERROR: swarm master is not available

read -n1 -r -p "Press any key to continue..." key

cho STEP 4: Run the swarm agent as a new docker container.
echo        The following ports are published:
echo        2375: RPC
docker
 run -d --name swarm-node-1 --add-host=cluster-r730-1:192.168.0.15 
--add-host=cluster-r730-k20-1:192.168.0.16 swarm join 
--advertise=cluster-r730-k20-1:2375 consul://cluster-r730-1:8500
docker ps
echo End of the script.
EOF

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