Packer vs Terraform: What are the differences?

Packer and Terraform are both popular tools used in the field of infrastructure automation and orchestration. While they serve different purposes, they have some key differences that set them apart.

1. Provisioning vs Orchestration: Packer is primarily focused on creating machine images or artifacts, while Terraform is more focused on managing and orchestrating the infrastructure those images will run on. Packer helps to create consistent and reproducible machine images, whereas Terraform helps to provision and manage the infrastructure resources.

2. Builders vs Providers: Packer uses a concept of builders to create machine images. These builders define where the images will be built, what type of machine they will be built on, and how the image will be created. Terraform, on the other hand, uses providers to manage resources within cloud platforms or infrastructure providers. These providers are responsible for creating, managing, and destroying infrastructure resources.

3. Image-centric vs Resource-centric: Packer is image-centric, meaning its focus is on the creation and management of machine images. It allows you to build a custom image with desired configurations and software. In contrast, Terraform is resource-centric, focusing on managing infrastructure resources like virtual machines, networks, storage, etc. It provides a declarative way to define the desired state of the infrastructure.

4. Immutable vs Mutable: Packer promotes the concept of immutable infrastructure, where machine images are built once and deployed multiple times without any modifications. This ensures consistency and eliminates configuration drift. Terraform, on the other hand, supports both immutable and mutable infrastructure. It allows provisioning and continuous modification of infrastructure resources, which can be beneficial in certain use cases.

5. Single-use vs Multi-use: Packer is typically used in a single-use scenario, where it is run to create a machine image, which is then used to deploy instances. Once the image is created, there is no further interaction with Packer. Terraform, on the other hand, is designed for multi-use scenarios. It allows you to define and manage infrastructure resources as code, facilitating continuous deployment and management of the infrastructure.

6. Concerns vs Abstractions: Packer primarily focuses on packaging applications and their dependencies into machine images, taking into account concerns like configuration management and provisioning. Terraform, on the other hand, abstracts infrastructure resources and allows you to define the desired state of the infrastructure, taking care of resource provisioning, lifecycle management, and dependency mapping.

In summary, Packer is focused on building machine images and is more image-centric, while Terraform is focused on managing and orchestrating the infrastructure and is more resource-centric. Packer promotes immutable infrastructure, is typically used in a single-use scenario, and is concerned with application packaging. Terraform, on the other hand, supports both immutable and mutable infrastructure, is designed for multi-use scenarios, and abstracts infrastructure resources for efficient management.