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Built-in blocks overview

This topic provides an overview of the configuration blocks built into the Packer language that you can use to write Packer templates in HCL2.

Introduction

A block is a container for configuration. You can use the following types of blocks in your Packer templates:

• build blocks contain configuration for a specific combination of builders, provisioners, and post-processors used to create a specific image artifact.
• source blocks contain configuration for builder plugins. Once defined, sources can be used and further configured by the "build" block.
• provisioner blocks contain configuration for provisioner plugins. These blocks are nested inside of a build block.
• post-processor and post-processors blocks contain configuration for post-processor plugins and post-processor plugin sequences. They are also nested within build blocks.
• variable blocks contain configuration for variables that can either be defaulted in configuration or set by the user at runtime.
• locals blocks contain configuration for variables that can be created using HCL functions or data sources, or composited from variables created in the variables blocks.

The documentation contains information for each block type.

Other blocks, such as the packer block, provide information to the Packer core about what version it is allowed to run. The required_plugins block helps the Packer core

Blocks can be defined in multiple files and packer build folder will build using solely the files from a directory named folder.

Packer does not support user-defined blocks and so only the blocks built in to the language are available for use. The documentation includes all of the available built-in HCL2 blocks.

Configuration examples

@include 'from-1.5/variables/foo-block.mdx'

• Variable block documentation.

@include 'from-1.5/locals/example-block.mdx'

• Locals block documentation.

@include 'from-1.5/sources/example-block.mdx'

• source block documentation.

@include 'from-1.5/builds/example-block.mdx'

• build block documentation.

@include 'from-1.5/datasources/example-block.mdx'

• data block documentation.