Strategies multi-environnement

Pourquoi plusieurs environnements ?

Les environnements multiples permettent de valider les changements progressivement avant la production. Un pipeline typique traverse dev, staging puis production.

Terraform Workspaces

Les workspaces Terraform isolent les fichiers d'etat (state) par environnement tout en partageant la meme configuration.

# Creer et basculer entre les workspaces
terraform workspace new dev
terraform workspace new staging
terraform workspace new production
terraform workspace select staging

# Utiliser le workspace dans la configuration
resource "aws_instance" "web" {
  ami           = var.ami_id
  instance_type = terraform.workspace == "production" ? "t3.large" : "t3.micro"

  tags = {
    Name        = "web-${terraform.workspace}"
    Environment = terraform.workspace
  }
}

# Variables par environnement
locals {
  env_config = {
    dev = {
      instance_count = 1
      db_size        = "db.t3.micro"
    }
    staging = {
      instance_count = 2
      db_size        = "db.t3.small"
    }
    production = {
      instance_count = 3
      db_size        = "db.t3.large"
    }
  }
  config = local.env_config[terraform.workspace]
}

Ansible Inventories par environnement

Ansible utilise des inventaires separes pour cibler chaque environnement :

# Structure des inventaires
inventories/
  dev/
    hosts.yml
    group_vars/
      all.yml
  staging/
    hosts.yml
    group_vars/
      all.yml
  production/
    hosts.yml
    group_vars/
      all.yml

# inventories/staging/hosts.yml
all:
  children:
    webservers:
      hosts:
        staging-web-01:
          ansible_host: 10.1.2.10
        staging-web-02:
          ansible_host: 10.1.2.11
    databases:
      hosts:
        staging-db-01:
          ansible_host: 10.1.3.10

# Execution ciblant un environnement
ansible-playbook -i inventories/staging site.yml

Kubernetes Namespaces

Les namespaces Kubernetes isolent les ressources par environnement sur un meme cluster :

# Creer les namespaces
kubectl create namespace dev
kubectl create namespace staging
kubectl create namespace production

# ResourceQuota par namespace
apiVersion: v1
kind: ResourceQuota
metadata:
  name: quota
  namespace: dev
spec:
  hard:
    requests.cpu: "2"
    requests.memory: 4Gi
    limits.cpu: "4"
    limits.memory: 8Gi
    pods: "20"

# NetworkPolicy pour isoler les namespaces
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: deny-cross-namespace
  namespace: production
spec:
  podSelector: {}
  policyTypes:
  - Ingress
  ingress:
  - from:
    - podSelector: {}