flatcar-terraform-hetzner

Flatcar Provisioning Automation for Hetzner Cloud

This repository provides tools to automate Flatcar provisioning on Hetzner Cloud using Terraform.

Features

• Minimal configuration required (demo deployment works with default settings w/o any customisation, just run terraform apply!).
• Deploy one or multiple servers.
• Per-server custom configuration via separate container linux config files.

Prerequisites

1. A Hetzner Cloud API token.

HowTo

This will create a server in Falkenstein using the smallest instance size available. See "Customisation" below for advanced settings.

1. Clone the repo.
2. Run

   terraform init

3. Edit server1.yaml and provide your own custom provisioning configuration in container linux config syntax.
4. Plan and apply. This will also auto-generate an SSH key pair to log in to the server after provisioning. The public key of that key pair will be registered with Hetzner.
   Optionally provide your Hetzner API token (see prerequisites above) in an environment variable. If it is not provided Terraform will prompt for the token on each run.

      export HCLOUD_TOKEN="..."

   Invoke Terraform:

   terraform plan
   terraform apply

Terraform will print server information (name, ipv4 and v6, and ID) after deployment concluded. The deployment will create an SSH key pair in .ssh/.

After provisioning concluded the private key of the key pair generated during provisioning can be used to connect to nodes:

ssh -i ./.ssh/provisioning_private_key.pem -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null core@[SERVER-IP]

NOTE that if you update server configuration(s) in server-configs and re-run terraform apply, the instance will be replaced. Consider adding create_before_destroy to the hcloud_server resource in hetzner-machines.tf to avoid services becoming unavailable during reprovisioning.

Customisation

The provisioning automation can be customised via settings in terraform.tfvars:

• cluster_name: Descriptive name of your cluster, will be used to generate server names. flatcar by default.
• machines: Add more machines to your deployment. Each machine name must be unique and requires a respective [NAME].yaml server configuration in server-configs. An example / default configuration for machine server1 is provided with server1.yaml. During provisioning, server names are generated by concatenating the cluster name and the machine name - the defaults above will create a single server named flatcar-server1.
• location: Hetzner Cloud region to deploy to. See here for a list of all locations: https://docs.hetzner.com/cloud/general/locations/
• server_type: See https://www.hetzner.com/cloud for a list (scroll down). Add additional yaml configurations if you added machines in terraform.tfvars.
• ssh_keys: Additional SSH public keys to add to core user's authorized_keys. Note that during provisioning, a provisioning RSA key pair will be generated and stored in the local directory .ssh/provisioning_private_key.pem and .ssh/provisioning_key.pub, respectively. The private key can be used for ssh connections (core user) to all provisioned servers.
• release_channel: Select one of "lts", "stable", "beta", or "alpha". Read more about channels here.