Scaling Terraform CI/CD Without Breaking Everything

As your team grows, more people are making infrastructure changes at the same time. That leads to problems. Scaling Terraform operations introduces a few major risks:

1. State corruption when multiple changes happen at once
2. Drift between Terraform code and what’s actually running
3. Exposed credentials from bad secrets management

If you’re not careful, these cause downtime, security issues, and a lot of debugging.

Concurrent Terraform operations

Terraform state corruption happens when multiple operations modify infrastructure at the same time. Since Terraform tracks resources in a state file, concurrent changes can cause inconsistencies between the state file and actual infrastructure. This leads to failed deployments and outages.

Tools like Atlantis prevent this by running operations sequentially, but that creates bottlenecks. As teams scale, waiting in line to deploy infrastructure slows things down.

Project isolation and layered deployments

Project isolation solves concurrency issues by keeping state files and infrastructure components separate.

terraform {
  backend "s3" {
    bucket         = "terraform-states"
    key            = "team1/production/network/terraform.tfstate"
    region         = "us-west-2"
    dynamodb_table = "terraform-locks"
  }
}

Separating infrastructure into independent layers or stacks that can run in parallel while maintaining dependencies can bring organization to your Terraform repository:

name: Terraform Layer Deployment

on:
  push:
    paths:
      - "network/**"
      - "compute/**"
      - "applications/**"

jobs:
  network_layer:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Deploy Network Layer
        working-directory: ./network
        run: terraform apply -auto-approve

  compute_layer:
    needs: network_layer
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Deploy Compute Layer
        working-directory: ./compute
        run: terraform apply -auto-approve

Tools like Terrateam make it easier to run Terraform in parallel and manage locks. It detects dependencies between infrastructure components and orchestrates deployments, so teams can make changes without stepping on each other’s toes.

Preventing infrastructure drift

Infrastructure drift happens when production resources don’t match what’s in Terraform. This creates reliability risks and security issues. Teams assume their Git repo reflects the real state of infrastructure, but that breaks down when engineers make manual changes (ClickOps) or when other tools modify resources outside of Terraform.

Automated drift detection

Here’s a simple GitHub Actions workflow that checks for drift every hour:

name: Terraform Drift Detection
on:
  schedule:
    - cron: '0 * * * *'
jobs:
  drift-detection:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: hashicorp/setup-terraform@v2
      - name: Terraform Init
        run: terraform init
      - name: Detect Drift
        run: terraform plan -detailed-exitcode
      - name: Create Issue on Drift
        if: ${{ failure() }}
        uses: actions/github-script@v6
        with:
          script: |
            github.rest.issues.create({
              owner: context.repo.owner,
              repo: context.repo.repo,
              title: 'Infrastructure Drift Detected',
              body: 'Terraform plan detected differences between desired and actual state.'
            })

Tools like driftctl detect unmanaged resources.

Secrets and Terraform

Infrastructure credentials need to be protected. If exposed, they can give attackers full access to your infrastructure. Storing secrets in S3 buckets or Terraform Cloud adds attack surfaces and makes access control more complicated.

Secret management

Tools like Infisical and AWS Secrets Manager store secrets securely with encryption and automatic rotation. They integrate with Terraform through built-in providers:

# AWS Secrets Manager Integration
data "aws_secretsmanager_secret_version" "db_creds" {
  secret_id = "prod/db/credentials"
}

locals {
  db_creds = jsondecode(data.aws_secretsmanager_secret_version.db_creds.secret_string)
}

resource "aws_db_instance" "main" {
  username = local.db_creds.username
  password = local.db_creds.password
}

Terraform has built-in features to protect sensitive data. The sensitive attribute hides secrets from logs and outputs:

variable "api_token" {
  type      = string
  sensitive = true
}

resource "aws_ssm_parameter" "api_token" {
  name  = "/app/api_token"
  type  = "SecureString"
  value = var.api_token
}

State file protection

Terraform’s storage configuration supports encrypted state storage. When using S3, you can enable server-side encryption and versioning:

terraform {
  backend "s3" {
    bucket = "terraform-state"
    key    = "prod/terraform.tfstate"
    region = "us-west-2"

    encrypt        = true
    kms_key_id     = "arn:aws:kms:us-west-2:111122223333:key/1234abcd"
    dynamodb_table = "terraform-locks"
  }
}

How Terrateam can help

Scaling Terraform for large teams means dealing with concurrency, drift, and secrets management. Terrateam automates Terraform CI/CD with safe concurrency, drift detection, and built-in secrets management. We’re open source, check out the repo at github.com/terrateamio/terrateam.