Managing Docker containers at scale requires a robust, repeatable approach that minimizes manual intervention and ensures consistency across environments. By combining Terraform and Ansible, you can achieve complete automation — from provisioning Docker hosts to deploying and configuring containers.

In this post, we’ll show how to use Terraform for infrastructure provisioning and Ansible for Docker configuration management, creating a powerful and flexible automation pipeline for container-based deployments.

Why Use Terraform and Ansible Together?

Tool Purpose Role in Docker Automation
Terraform Infrastructure Provisioning Create Docker hosts (VMs, cloud resources)
Ansible Configuration Management Install Docker, deploy and manage containers

Using both enables infrastructure as code (IaC) with Terraform and idempotent configuration using Ansible playbooks — ideal for DevOps workflows and CI/CD pipelines.

Architecture Overview

[Terraform]
↓
Provision VM or cloud instance (EC2, GCP, etc.)
↓
[Ansible]
↓
Install Docker, deploy containers, manage volumes/networks

You can also use Terraform to dynamically generate Ansible inventory for seamless integration.

Step 1: Provision Infrastructure with Terraform

Example Terraform script to launch a Docker host on AWS EC2:

provider "aws" {
region = "us-east-1"
}

resource "aws_instance" "docker_host" {
ami           = "ami-0c02fb55956c7d316"
instance_type = "t2.micro"

tags = {
Name = "docker-node"
}

provisioner "remote-exec" {
inline = [
"sudo apt-get update",
"sudo apt-get install -y python3"
]

    connection {
      type        = "ssh"
      user        = "ubuntu"
      private_key = file("~/.ssh/id_rsa")
      host        = self.public_ip
    }
}
}

Once created, Terraform can output the instance IP to be used in your Ansible inventory.

Step 2: Create Ansible Playbook for Docker Setup

Sample playbook: docker.yml

---
- hosts: docker_hosts
  become: true
  tasks:
  - name: Install Docker
    apt:
    name: docker.io
    state: present
    update_cache: true

  - name: Start Docker
    service:
    name: docker
    state: started
    enabled: true

  - name: Run NGINX container
    docker_container:
    name: web
    image: nginx:latest
    state: started
    ports:
    - "80:80"
    ```

---

#### Step 3: Dynamically Generate Ansible Inventory from Terraform

You can output instance IPs from Terraform:

```hcl
output "docker_host_ip" {
value = aws_instance.docker_host.public_ip
}

Save the IPs to a dynamic inventory file for Ansible:

[docker_hosts]
<terraform-output-ip> ansible_user=ubuntu ansible_ssh_private_key_file=~/.ssh/id_rsa

Step 4: Run the Automation Pipeline

  1. Apply Terraform:
terraform init
terraform apply
  1. Get the output IP:
terraform output docker_host_ip
  1. Add IP to Ansible inventory and run playbook:
ansible-playbook -i inventory.ini docker.yml

This deploys Docker and runs your containers automatically.

Best Practices

  • Store Terraform and Ansible in separate directories for clean separation
  • Use remote state (Terraform Cloud, S3) for team collaboration
  • Encrypt secrets using Ansible Vault
  • Parameterize playbooks and Terraform with variables
  • Use Ansible roles for reusable Docker setups
  • Automate via GitHub Actions, Jenkins, or GitLab CI

Real-World Use Cases

  • Auto-scaling container hosts across cloud environments
  • Deploying microservices without Kubernetes
  • Setting up test environments in CI pipelines
  • Managing dev/QA Docker infrastructure as code

Conclusion

Combining Terraform and Ansible for Docker container automation offers the best of both worlds — scalable provisioning with infrastructure as code and powerful, declarative configuration management. This workflow enables teams to deploy reliable, repeatable, and production-grade Docker environments across cloud and on-premises infrastructure.

Use this approach to streamline your DevOps pipelines, reduce manual errors, and embrace modern infrastructure automation practices.