Terraform Testing with Terratest

You write a Terraform module. You run terraform plan. It looks right. But does it actually create working infrastructure? Terratest deploys your Terraform, validates the result, and tears it down — automated infrastructure integration tests.

How Terratest Works

Test starts → terraform init/apply → Validate resources → terraform destroy → Test ends

Terratest calls Terraform, waits for resources to be created, runs assertions against them, and cleans up.

Basic Test

// test/vpc_test.go
package test

import (
    "testing"
    "github.com/gruntwork-io/terratest/modules/terraform"
    "github.com/stretchr/testify/assert"
)

func TestVpc(t *testing.T) {
    t.Parallel()

    terraformOptions := &terraform.Options{
        TerraformDir: "../modules/vpc",
        Vars: map[string]interface{}{
            "vpc_cidr":     "10.0.0.0/16",
            "environment":  "test",
            "subnet_count": 2,
        },
    }

    // Clean up after test
    defer terraform.Destroy(t, terraformOptions)

    // Deploy
    terraform.InitAndApply(t, terraformOptions)

    // Validate outputs
    vpcId := terraform.Output(t, terraformOptions, "vpc_id")
    assert.NotEmpty(t, vpcId)

    subnetIds := terraform.OutputList(t, terraformOptions, "subnet_ids")
    assert.Equal(t, 2, len(subnetIds))
}

bash

cd test/
go test -v -timeout 30m

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HTTP Validation

Test that deployed infrastructure actually works:

func TestWebServer(t *testing.T) {
    t.Parallel()

    terraformOptions := &terraform.Options{
        TerraformDir: "../modules/web-server",
    }

    defer terraform.Destroy(t, terraformOptions)
    terraform.InitAndApply(t, terraformOptions)

    // Get the public URL
    url := terraform.Output(t, terraformOptions, "url")

    // Validate HTTP response
    http_helper.HttpGetWithRetry(t, url, nil, 200, "Hello, World!", 30, 10*time.Second)
}

Terratest retries the HTTP request up to 30 times (infrastructure might take a moment to be ready).

SSH Validation

func TestSshAccess(t *testing.T) {
    terraformOptions := &terraform.Options{
        TerraformDir: "../modules/bastion",
    }

    defer terraform.Destroy(t, terraformOptions)
    terraform.InitAndApply(t, terraformOptions)

    publicIp := terraform.Output(t, terraformOptions, "public_ip")
    keyPair := terraform.Output(t, terraformOptions, "private_key")

    host := ssh.Host{
        Hostname:    publicIp,
        SshUserName: "ubuntu",
        SshKeyPair:  &ssh.KeyPair{PrivateKey: keyPair},
    }

    // Run command over SSH
    output := ssh.CheckSshCommand(t, host, "echo 'Hello from $(hostname)'")
    assert.Contains(t, output, "Hello from")
}

Testing Kubernetes Resources

func TestKubernetesDeployment(t *testing.T) {
    terraformOptions := &terraform.Options{
        TerraformDir: "../modules/k8s-app",
    }

    defer terraform.Destroy(t, terraformOptions)
    terraform.InitAndApply(t, terraformOptions)

    kubeconfig := terraform.Output(t, terraformOptions, "kubeconfig")

    options := k8s.NewKubectlOptions("", kubeconfig, "production")

    // Wait for deployment to be available
    k8s.WaitUntilDeploymentAvailable(t, options, "order-api", 30, 10*time.Second)

    // Validate pod count
    deployment := k8s.GetDeployment(t, options, "order-api")
    assert.Equal(t, int32(3), *deployment.Spec.Replicas)

    // Validate service
    service := k8s.GetService(t, options, "order-api")
    assert.Equal(t, int32(8080), service.Spec.Ports[0].Port)
}

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Test Structure

modules/
├── vpc/
│   ├── main.tf
│   ├── variables.tf
│   └── outputs.tf
├── web-server/
│   ├── main.tf
│   ├── variables.tf
│   └── outputs.tf
test/
├── vpc_test.go
├── web_server_test.go
├── go.mod
└── go.sum

CI/CD Integration

yaml

# GitHub Actions
jobs:
  infrastructure-tests:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version: "1.22"
      - uses: hashicorp/setup-terraform@v3

      - name: Run Terratest
        working-directory: test/
        run: go test -v -timeout 30m -parallel 4
        env:
          AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
          AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}

Best Practices

Use unique names: Append random suffixes to avoid collisions between parallel tests:

uniqueId := random.UniqueId()
terraformOptions := &terraform.Options{
    Vars: map[string]interface{}{
        "name": fmt.Sprintf("test-%s", uniqueId),
    },
}

Run tests in parallel: Each test deploys independently:

func TestVpc(t *testing.T)       { t.Parallel(); /* ... */ }
func TestWebServer(t *testing.T) { t.Parallel(); /* ... */ }

Set timeouts: Infrastructure takes time:

bash

go test -v -timeout 30m

Always defer destroy: Even if assertions fail, cleanup runs:

defer terraform.Destroy(t, terraformOptions)

---

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Luca Berton

Docker Captain, IT automation expert, Red Hat Summit & KubeCon speaker. Building hands-on education for DevOps engineers at CopyPasteLearn.

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Terraform Testing with Terratest

How Terratest Works

Basic Test

Master this topic with hands-on labs

HTTP Validation

SSH Validation

Testing Kubernetes Resources

Get weekly IT automation tips

Test Structure

CI/CD Integration

Best Practices

Ready to learn by doing?

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