»Checksum Post-Processor

Type: checksum

The checksum post-processor computes specified checksum for the artifact list from an upstream builder or post-processor. All downstream post-processors will see the new artifacts. The primary use-case is compute checksum for artifact to verify it later.

After computes checksum for artifacts, you can use new artifacts with other post-processors like artifice, compress, docker-push, or a third-party post-processor.

»Basic example

The example below is fully functional.

{
  "type": "checksum"
}

»Configuration Reference

Optional parameters:

• checksum_types (array of strings) - An array of strings of checksum types to compute. Allowed values are md5, sha1, sha224, sha256, sha384, sha512.

• keep_input_artifact (boolean) - Unlike most post-processors, setting keep_input_artifact will have no effect; the checksum post-processor always saves the artifact that it is calculating the checksum for.

• output (string) - Specify filename to store checksums. This defaults to packer_{{.BuildName}}_{{.BuilderType}}_{{.ChecksumType}}.checksum. For example, if you had a builder named database, you might see the file written as packer_database_docker_md5.checksum. This is treated as a template engine. Therefore, you may use user variables and template functions in this field. The following special variables are also available to use in the output template:

  • BuildName: The name of the builder that produced the artifact.
  • BuilderType: The type of builder used to produce the artifact.
  • ChecksumType: The type of checksums the file contains. This should be used if you have more than one value in checksum_types.