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Vincent Mogah
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Cloud

Hybrid Cloud GitOps Control Plane (Terraform + ArgoCD)

Hub-and-spoke GitOps platform: Terraform provisions OCI OKE (hub) and a spoke cluster, while Argo CD continuously reconciles platform + apps from Git.

Historical deployment. The hosted environment has been retired; source and recorded evidence remain available.

Hybrid Cloud GitOps Control Plane (Terraform + ArgoCD) recorded evidence
Recorded project evidence. The case study below describes the implementation and its limits.

OCI · OKE · K3s · Terraform · ArgoCD · GitOps · Helm · Kustomize · LGTM

Overview

Hub-and-spoke GitOps: OCI OKE (hub) manages a remote K3s cluster (spoke) from one Git repository.

  • Terraform provisions OCI resources and cluster primitives
  • Argo CD reconciles application and observability state from Git

Always Free constraints

The deployment ran the LGTM stack (Loki, Grafana, Tempo, Mimir) within an OCI Always Free 200GB storage budget.

  • Persistent volumes only where state matters
  • Ephemeral emptyDir for transient components such as Alertmanager

Multi-cluster GitOps

  • Argo CD on the OKE hub manages the remote K3s spoke
  • One Git repository for infra, ops, and apps
  • Argo CD Multi-Source splits ops/ from app charts and manifests

Links

Cost and recovery

  • Egress tracker aligned to a 10TB/month limit via PromQL queries
  • Stateful workloads (MongoDB/NATS) use Retain policies; ops/ Kustomize app adopted by Argo CD

Hybrid Cloud GitOps Architecture showing Terraform provisioning OCI OKE and ArgoCD managing K3s Rocket.Chat deployments

Outcomes

Terraform + Argo CD across OKE and K3s, with Always Free storage budgeting and multi-source app layout.

Challenges and solutions

Challenges

  • Operating within Always Free constraints without overselling uptime or capacity
  • Keeping a clear separation between “infra”, “ops”, and “apps” while still using one repo
  • Managing a remote K3s cluster safely from a central ArgoCD control plane
  • Avoiding storage surprises by explicitly budgeting PV usage and ephemeral state

Solutions

  • Terraform-managed OCI lifecycle for reproducible cluster creation and change control
  • ArgoCD reconciliation as the single source of truth for application + observability state
  • Adopted ArgoCD Multi-Source to keep ops/app boundaries clean and upgrades predictable
  • Cost-control instrumentation (egress tracking) and Retain policies for stateful recovery

Technology stack

Kubernetes

OCI OKE · K3s · Helm · Kustomize

GitOps

ArgoCD · ArgoCD Multi-Source

IaC

Terraform

Observability

Grafana · Loki · Tempo · Mimir

Operations

PromQL cost signals · Retain policies

View source code