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linode-k8s-cluster

General

This repository contains:

  1. the minimum Terraform scaffolding necessary to spin up a Kubernetes cluster on Linode.

  2. a Makefile with a suite of commands for creating, and tearing down, a Kubernetes cluster on Linode via these .tf files on a local machine.

  3. a Github Action Workflow which runs terraform apply on this repository's .tf files when a new Release is published, thus either creating a new or updating a pre-existing Kubernetes cluster on Linode with that Release's changes.

Makefile

Configuration

The Makefile must be paired with an .env file containing all necessary credentials, which are:

VAULT_ADDR
VAULT_NAMESPACE
VAULT_TOKEN
CONSUL_HTTP_TOKEN
TF_VAR_LINODE_KUBERNETES_API_TOKEN
KUBECONFIG
GH_TOKEN

Commands

  • init runs terraform init
  • terraform_fmt runs terraform fmt
  • plan_destroy runs terraform plan -destroy
  • destroy runs terraform destroy
  • get_kube_config gets the kubeconfig file for a newly created Kubernetes cluster
  • plan runs terraform plan
  • apply runs terraform apply
  • generate_new_vault_token_for_github generates a new VAULT_TOKEN
  • list_releases lists all Github Releases for this repo
  • create_release creates a new published Releaseon github, taking two arguments:
    1. tag='v0.0.0' - the version number for the release in Semver
    2. description='text' - the description string for the Release

Terraform

main.tf is configured to use Consul as a backend state store and Linode as its sole Provider.

Github Action Workflow

When triggered by a published release, the GitHub action Workflow reaches out to a Vault server to retrieve credentials for both Consul nd Linode and then runs terraform fmt, terraform plan and terraform apply.

This is the relevant part of the Workflow which must be configured with a Vault endpoint url and API token as well as the precise paths of the secrets to be fetched:

      - uses: hashicorp/vault-action@v2.4.0
        with:
          url: ${{ env.vault_endpoint}}
          tlsSkipVerify: true
          method: token
          namespace: admin/yoyodynecorp
          token: ${{ secrets.VAULT_API_TOKEN }}
          secrets: |
            secret/data/github_action_linode_terraform LINODE_KUBERNETES_API_TOKEN ;
            secret/data/github_action_linode_terraform CONSUL_API_TOKEN

Else on all pull requests, terraform fmt and terraform plan are run to verify correctness.