Single script for Docker Swarm cluster setup

Question

I have the Docker Swarm cluster setup in my preprod servers(3 manager node and 7 worker nodes); however I would like to replicate the same in Production servers but rather than using commands I prefer using a script.

At present I am using "docker swarm init" to initialize the swarm and then adding the workers and managers with the generated key.

I would have 30 servers and planning for 7 manager and 23 worker nodes. I have searched the net; but could not find any script which can initialize the docker swarm automatically with a script in all the servers.

Any help would really appreciated.

Answer 1

There is nothing like in-built utilities for that you can use the command like this :

You can create your custom script like this :

for i in `cat app_server.txt` ; do echo $i ; ssh -i /path/to/your_key.pem  $i "sudo docker swarm join --token your-token-here ip-address-of-manager:port" ; done

Here app_server.txt is the ip address of your worker node that you want to add in your swarm.

--token : your token generated by manager on docker swarm init

Hope this may help.

You can also use ansible for the same but that require ansible docker modules installed on all the worker nodes. Thank you!

Answer 2

The way I approached this was to have a common build script for all nodes, and to use Consul for sharing the docker swarm manager token with the rest of the cluster.

The first node (at 10.0.0.51 ) calls docker swarm init and places the token in the key value store, and the remaining nodes (at 10.0.0.52 onwards) read the token back and use it to call docker swarm join .

The bash looked something like this -

# Get the node id of this machine from the local IP address
privateNetworkIP=`hostname -I | grep -o 10.0.0.5.`
nodeId=`(echo $privateNetworkIP | tail -c 2)`

if [ $nodeId -eq 1 ]; then

    sudo docker swarm init
    MANAGER_KEY_IN=`sudo docker swarm join-token manager -q`
    curl --request PUT --data $MANAGER_KEY_IN http://10.0.0.51:8500/v1/kv/docker-manager-key

else 

    MANAGER_KEY_OUT=`curl -s http://10.0.0.51:8500/v1/kv/docker-manager-key?raw`
    sudo docker swarm join --token $MANAGER_KEY_OUT 10.0.0.51:2377

fi

... and works fine provided that node 1 is built first.