Set up a Docker Swarm Cluster on Digital Ocean using Terraform

This repository is meant to serve as an example of using Terraform. Basic security measures such as setting up a firewall, turning off SSH password access, turning off SSH root access, and creating non-root users are not in place. Use this repository for learning purposes only, not for setting up a production Docker Swarm deployment.

Before getting started, you will need to generate an API token so Terraform can access your DigitalOcean account. To generate an API token all you need to do is log in to your account, click "API" in the top navigation bar, and then click "Generate New Token." Give the token a name and make sure you enable read and write access. Copy down the API token and keep it somewhere safe -- DigitalOcean will not show you the token again. If you lose the token you will have to generate a new one.

Use the following command to generate a public and private key-pair:

ssh-keygen -o -a 100 -t ed25519 -C dockerswarm@digitalocean

By default this will create two files: ~/.ssh/id_ed25519 and ~/.ssh/id_ed25519.pub. When the command runs you will have an opportunity to use a different location if you want. Make sure you use a strong passphrase when generating the key. Once the keys are generated use the following command to add the private key to your SSH agent:

ssh-add ~/.ssh/id_ed25519

Create a file in this repository named terraform.tfvars with contents as such:

do_token="DIGITALOCEAN API TOKEN"
public_key_path="~/.ssh/id_ed25519.pub"

Replace DIGITALOCEAN API TOKEN with your actual API token and ~/.ssh/id_ed25519 with the path to your public key.

Run the following command to see what changes terraform will make to your DigitalOcean account:

terraform plan

If everything looks good, go ahead and run:

terraform apply

Congratulations! You know have a functioning four-node Docker Swarm cluster!

See my accompanying blog post for more information, including how to deploy services and how to scale the swarm.

MIT