title: Understand DevOps in One Article—This is How Packer, Terraform, Docker, and K8s Divide Their Work! summary: In the world of DevOps, with so many tools, many people get confused about their responsibilities. Using a car industry analogy, this article helps you understand the positioning and collaboration of Packer, Terraform, Ansible, Docker, and Kubernetes all at once. tags:
- DevOps
date: 2025-12-10
authors:
- shenxianpeng
In the world of DevOps, with so many tools, many people get confused about their responsibilities. The most typical questions are: What exactly do Packer, Terraform, and Ansible do? And where do Docker and Kubernetes fit in? What about VMs?
In fact, if you imagine them all as a set of processes for “manufacturing cars, buying cars, tuning cars, driving cars, and operating a fleet,” it becomes very clear.
Today, using a more complete car factory analogy, I’ll help you understand it all at once:
DevOps Tools = A Car Life Cycle Industry Chain#
To make the analogy natural, we’ll divide the entire IT Infra life cycle into three stages:
- Build Time: Car Manufacturing
- Provision Time: Car Purchasing / Allocating Parking Spaces
- Run Time: Driving Cars / Managing the Fleet
Then, mapping each DevOps tool to these stages will be very intuitive.
1. Packer — The “Pre-assembly Stage” in a Car Factory#
Role: Car Factory Production Line Stage: Build Time
Do you need a car that’s “fueled up, seats adjusted, and navigation configured”? Packer is what assembles all of these in the factory, then packages them into an image (AMI, VMDK, Docker Image, QCOW2, etc.).
Analogy: Packer is the factory worker who “pre-assembles the car”. The engine is installed, seats are adjusted, and software is pre-installed.
This way, when the car gets to you, it’s “ready to use out of the box”.
2. Terraform — The Fleet Manager and Parking Lot Administrator#
Role: Managing the Fleet, Scheduling Resources, Building Parking Lots Stage: Provision Time
Terraform doesn’t build cars or drive them; its job is:
- Deciding how many cars to buy
- Which garage to put them in
- How big of a parking lot to build (VPC, Subnet)
- Assigning parking spaces for each car (VM, EC2, K8s nodes, LB, and other resources)
It is responsible for the planning and creation of the entire fleet and infrastructure environment.
Analogy: Terraform is the fleet manager, saying: “We need three trucks, two sedans, parked in Garage Zone A, and build a charging station next to it.”
3. Ansible — The Good Driver / Mechanic#
Role: Vehicle Adjustment and Configuration Stage: Provision Time
The car is built and purchased, but before hitting the road, you still need to:
- Adjust the rearview mirrors
- Set up navigation
- Install extra accessories on the car
- Replace software, start services
This is Ansible’s job.
Analogy: Ansible is the driver, also the mechanic, responsible for “all configurations after the car starts”.
Of course, if you use Packer to do the work in advance within the image, then Ansible’s runtime work will be even less.
4. Docker — Your “Personal Car” (Application Container)#
Role: Single Car Stage: Build & Run
Docker is not a fleet; it’s individual cars (containers). Each container is a “mini-car”:
- Independent, secure
- Fast startup
- Comes with a “car shell” (image)
- Does not affect each other
- Can be driven on any “road” (different environments)
Analogy: Docker is a “lightweight, unified, standard” small car; each car comes with its own operating instructions, no need to adapt to the ground environment.
5. Virtual Machine (VM) — Renting a Piece of Land to Build Parking Spaces#
Role: Parking Space / Plot Stage: Provision Time
A virtual machine is a “designated parking space and road”. On this plot, you can:
- Install an operating system
- Run applications
- Run Docker
- Run databases
VM is the most fundamental layer of infrastructure.
Analogy: A VM is an “individual parking space in a garage”. The car must be parked here before further configuration and operation can proceed.
6. Kubernetes — Intelligent Dispatch System for Large-Scale Fleets#
Role: Fleet Operation Platform Stage: Run Time
If you have one car, Docker is enough; If you have 1000 cars, you need an intelligent system to:
- Automatically assign vehicles
- Automatically repair cars, restart faulty vehicles
- Scale up, scale down
- Assign roads, traffic rules for vehicles
- Ensure continuous operation of the entire fleet
This is Kubernetes.
Analogy: Kubernetes is a “super intelligent fleet management platform”. Responsible for the operation, traffic, and health of all cars in the entire city.
How Do These Tools Collaborate? (Complete Workflow)#
Looking at it from the “Build Car → Buy Car → Drive Car” life cycle:
| Stage | Action | Tool | Analogy |
|---|---|---|---|
| Build Time | Build Standard Car | Packer | Factory Pre-assembly of Vehicles |
| Provision Time | Buy Car, Build Parking Lots | Terraform | Fleet Manager Selects Cars & Plans Garages |
| Provision/Run | Adjust Vehicles, Install Software | Ansible | Driver/Mechanic |
| Build & Run | Run Application Car | Docker | Single Standardized Small Car |
| Run Time | Manage the Entire Fleet | Kubernetes | Intelligent Fleet Dispatch System |
| Infra Base | Parking Space | VM | Individual Parking Space in a Garage |
With this table, you can clearly understand the responsibilities and collaboration methods of each tool.
Conclusion#
Each DevOps tool has its own positioning; there’s no question of “which is more advanced,” only “which is more suitable for that stage.”
If this article helped you clarify the relationships between these tools, feel free to share it with your teammates so everyone can avoid some pitfalls.
If you’d like me to write more similar everyday explanations of DevOps in the future, please let me know.
