Why GitFlow Fails at Infrastructure

The Core Problem: The “Third Dimension”

Applying GitFlow to Terraform frequently results in “State Drift” and fragile pipelines, unlike application code which has only two dimensions: code and build. Terraform introduces a crucial third dimension – State – which cannot be merged using standard git merge.

This divergence between code, state, and the live infrastructure leads to inconsistencies and potential failures during deployments, impacting infrastructure stability and increasing operational costs.

Key Insights

• State Drift: A common Terraform issue where the tracked state diverges from the actual infrastructure, leading to unpredictable behavior.
• Trunk-Based Development: A branching strategy promoting frequent commits to the main branch, enabling faster feedback and reducing integration issues.
• Terraform Modules & Versioning: Essential for managing reusable infrastructure components and preventing breaking changes across teams.

Working Example

# Directory Structure:
/my-infra
/modules
/vpc
/k8s
main.tf <-- The generic entry point
variables.tf <-- Definitions only
config/
dev.tfvars <-- Dev specific values (instance_type="t3.micro")
prod.tfvars <-- Prod specific values (instance_type="m5.large")

# CI/CD Command Logic (Dev Stage):
terraform init -backend-config="bucket=my-tf-state-dev"
terraform plan -var-file="config/dev.tfvars" -out=tfplan
terraform apply tfplan

Practical Applications

• Netflix: Employs Trunk-Based Development with Terraform to manage its extensive cloud infrastructure, enabling rapid deployments and minimizing configuration drift.
• Pitfall: Mapping Git branches to environments (e.g., dev to Development, main to Production) creates state divergence, leading to “State Stomping” or “Phantom Infrastructure.”

References:

• https://dev.to/dortort/why-gitflow-fails-at-infrastructure-90f
• https://www.terraform.io/docs/state/index.html
• https://www.terraform.io/docs/remote-state/index.html
• https://www.terraform.io/docs/workspaces/index.html
• https://www.terraform.io/cloud/docs/best-practices/workflows