Packer FAQ

What is Packer?

Packer is an open-source tool created by HashiCorp for building identical machine images for multiple platforms from a single source configuration. It automates the process of creating machine images, eliminating manual steps and ensuring consistency across different environments.

Why use Packer?

Packer offers several advantages, including:

• Fast infrastructure deployment: Images built by Packer can launch fully provisioned machines in seconds.

• Multi-provider portability: Create identical images for various platforms like AWS, Azure, GCP, VMware, etc.

• Improved stability: Detects configuration errors early in the build process.

• Greater testability: Enables automated testing of images for increased reliability.

• Immutable infrastructure: Facilitates deploying updated, patched images instead of updating existing systems.

• Version controlled images: Packer configurations can be versioned, ensuring consistent and reproducible builds.

What is a Packer template?

A Packer template is a configuration file written in either JSON or HCL2 (HashiCorp Configuration Language) that defines the instructions for building machine images. It specifies the builder, provisioners, post-processors, and other settings required for the image creation process.

What are builders in Packer?

Builders are responsible for creating machines and generating images from them for various platforms. Packer supports a wide range of builders for popular platforms like AWS, Azure, GCP, VMware, VirtualBox, Docker, and more. Builders act as plugins, enabling communication with specific platforms to create the desired image format.

What are provisioners in Packer?

Provisioners are used to install and configure software within a running machine before it's turned into a static image. They perform tasks such as installing packages, patching the kernel, creating users, downloading application code, and running configuration management tools like Ansible, Chef, or Puppet.

What are post-processors in Packer?

Post-processors run after the image is built by the builder and provisioned. They are used to perform additional tasks like:

• Uploading the image to a cloud provider or registry.

• Compressing the image.

• Converting the image to different formats.

• Validating the image with checksums.

What are communicators in Packer?

Communicators provide a mechanism for Packer to connect to and interact with the machine being built. They are responsible for establishing connections and transferring files and commands. Packer supports communicators like SSH and WinRM, with some builders having custom communicators.

What are data sources in Packer?

Data sources allow Packer to fetch data from external sources for use in a template. This enables builds to use information defined outside of Packer. Data sources are only available in HCL2 templates and are helpful for accessing dynamic information, such as the latest AMI ID or secrets from a vault.