The goal of Plural Stacks is to provide a scalable framework to manage infrastructure as code like Terraform, Ansible and Pulumi with a kubernetes-friendly, api-driven approach. The core workflow is as follows:

• Declaratively define a stack with a type (terraform, ansible, etc), a location in a git repository to source code from, and a cluster on which it will execute
• On each commit to the tracked git repository, a run is created which the Plural deployment operator will detect and execute on the targeted cluster
  • this allows users to fine grain permissions and network location of IaC runs where both are necessary to configure.
• Plural will carefully execute the run for you, and besides basic information like communicating stdout to the UI, we will also gather and present useful information like inputs/outputs, terraform state diagrams and more
• On PRs to the tracked repository, a "plan" run is also executed and comments posted on the relevant PR where possible.

To get a better idea of the full power of the experience, feel free to take a look at this demo video (at 2x speed if you want to save some time):

A Basic Stack

The most common way to instantiate a stack is via Kubernetes CRD. This gives a flexible, modular way of recreating infrastructure with Terraform and pairs nicely with our PR Automation tooling for full self-service around IaC.

Here's an example:

apiVersion: deployments.plural.sh/v1alpha1
kind: InfrastructureStack
metadata:
  name: gke-demo
  namespace: stacks
spec:
  name: gke-demo
  type: TERRAFORM
  approval: true
  detach: false
  manageState: true
  actor: console@plural.sh
  configuration:
    version: 1.8.2
  repositoryRef:
    name: fleet
    namespace: fleets
  clusterRef:
    name: mgmt
    namespace: infra
  workdir: gke-cluster
  git:
    ref: main
    folder: terraform
  files:
  - mountPath: /plural
    secretRef:
      name: gcp-creds
  environment:
  - name: GOOGLE_APPLICATION_CREDENTIALS
    value: /plural/creds.json
  - name: TF_VAR_cluster
    value: gke-demo
  - name: TF_VAR_tier
    value: dev
  - name: TF_VAR_fleet
    value: gke-dem

The meaning of this yaml is pretty self-documenting, we are:

• creating a TERRAFORM stack, so it will execute the standard terraform workflow
• we're using Plural as the state store, removing the need to configure S3 or other backends manually
• approval will be required before terraform apply will trigger, ensuring a human verifies the plan first to reduce misconfiguration risk
• we're sourcing manifests from the fleet repository (referencing a GitRepository crd)
• we're executing on the mgmt cluster (referencing a Cluster crd)
• and we're executing in the terraform/gke-cluster folder