1. Moving from CapEx to OpEx #
How the cloud transforms IT accounting.
The end of 5-year depreciation #
In the traditional model (CapEx), you buy hardware. In the cloud (OpEx), you pay a variable monthly bill. This requires constant monitoring to avoid 'cloud waste' (resources paid for but not used).
2. The 3 phases of the FinOps framework #
- Inform: give visibility into costs by team through tagging.
- Optimize: use reserved instances or right-size oversized resources.
- Operate: automate day-to-day financial governance.
3. Savings strategies #
Using 'spot' instances (up to 90% discount) for non-critical tasks and automatically shutting down test environments on weekends are quick wins for any FinOps program.
Hands-on: measuring and reducing costs #
FinOps commands and queries.
Visualizing costs #
# Coût par service sur le mois (AWS)
aws ce get-cost-and-usage --time-period Start=2026-10-01,End=2026-11-01 --granularity MONTHLY --metrics UnblendedCost \
--group-by Type=DIMENSION,Key=SERVICE | jq -r '.ResultsByTime[].Groups[] | [.Keys[0], .Metrics.UnblendedCost.Amount] | @tsv' | sort -k2 -nr | head
# Ressources inutilisées : volumes détachés et IP non associées
aws ec2 describe-volumes --filters Name=status,Values=available --query 'Volumes[].[VolumeId,Size]' --output table
aws ec2 describe-addresses --query 'Addresses[?AssociationId==null].PublicIp'
# Azure / GCP
az consumption usage list --top 20 -o table
gcloud billing accounts listThe three levers #
- Rightsizing: adjust instance size to actual consumption (
kubectl top, CloudWatch metrics). - Commitments: Reserved Instances / Savings Plans for stable workloads.
- Cleanup and scheduling: shut down non-production environments at night and on weekends.
# Étiquetage obligatoire pour répartir les coûts
aws ec2 create-tags --resources i-0123456789abcdef0 --tags Key=equipe,Value=paiement Key=env,Value=prod
kubectl scale deployment --all --replicas=0 -n dev # extinction nocturne des environnements de dev