Packer vs Stacker 1: What are the differences?

Introduction

Packer and Stacker are both tools used for building machine images or containers automatically. However, there are key differences between these two tools that set them apart.

1. Build Process Approach: Packer follows a virtual machine (VM)-centric approach, where it creates a VM and provisions it with necessary software, then creates an image from it. On the other hand, Stacker utilizes container technology, where it builds a container image by layering the necessary software components, resulting in a more lightweight and faster build process.

2. Build Artifact: Packer generates various artifacts as output, such as Amazon Machine Images (AMI), VirtualBox images, or Docker containers. It supports multiple platforms and offers flexibility for different deployment scenarios. Stacker, on the other hand, primarily focuses on building Docker container images, making it more specialized for containerized environments.

3. Configuration Language: Packer uses HashiCorp Configuration Language (HCL) for defining its build configurations. HCL provides a concise and expressive syntax with support for variables, templates, and conditionals. Stacker, on the other hand, allows the use of YAML or JSON as the configuration language, providing a more familiar and flexible approach for defining and managing stack files.

4. Orchestration Capability: Packer mainly focuses on building images through the integration of various builders, provisioners, and post-processors. It does not provide robust orchestration capabilities for managing multiple build stages or dependencies. In contrast, Stacker provides advanced orchestration features, allowing the definition of complex workflows and dependencies between different stack files, making it suitable for more complex and interconnected infrastructure deployments.

5. Community and Ecosystem: Packer has a larger community following and a more mature ecosystem. It has extensive documentation, active community support, and a wide range of plugins available for integrating with different infrastructures and services. Stacker, being a relatively newer tool, has a smaller community but is gaining traction as containerization becomes more popular.

6. Continued Development: Packer has been actively developed and maintained by HashiCorp for many years, with regular updates and bug fixes. It is widely used in production environments and has a strong commitment to backward compatibility. Stacker, being a newer tool, is still evolving and may have a more rapid pace of development, introducing new features and improvements more frequently.

In summary, Packer and Stacker differ in their build process approach, supported artifacts, configuration language, orchestration capabilities, community, and development focus. While Packer offers more flexibility and broader platform support, Stacker specializes in building Docker containers with a focus on orchestration and simplicity.