Packer Commands (CLI)
Packer is controlled using a command-line interface. All interaction with
Packer is done via the
packer tool. Like many other command-line tools, the
packer tool takes a subcommand to execute, and that subcommand may have
additional options as well. Subcommands are executed with
where "SUBCOMMAND" is the actual command you wish to execute.
If you run
packer by itself, help will be displayed showing all available
subcommands and a brief synopsis of what they do. In addition to this, you can
packer command with the
-h flag to output more detailed help for a
The documentation contains information about each subcommand.
By default, the output of Packer is very human-readable. It uses nice formatting, spacing, and colors in order to make Packer a pleasure to use. However, Packer was built with automation in mind. To that end, Packer supports a fully machine-readable output setting, allowing you to use Packer in automated environments.
Because the machine-readable output format was made with Unix tools in mind, it
grep/etc. friendly and provides a familiar interface without
requiring you to learn a new format.
The machine-readable output format can be enabled by passing the
-machine-readable flag to any Packer command. This immediately enables all
output to become machine-readable on stdout. Logging, if enabled, continues to
appear on stderr. An example of the output is shown below:
$ packer -machine-readable version 1498365963,,version,1.0.2 1498365963,,version-prelease, 1498365963,,version-commit,3ead2750b+CHANGES 1498365963,,ui,say,Packer v1.0.2
The format will be covered in more detail later. But as you can see, the output
immediately becomes machine-friendly. Try some other commands with the
-machine-readable flag to see!
-machine-readable flag is designed for automated environments and
is mutually-exclusive with the
-debug flag, which is designed for interactive
The machine readable format is a line-oriented, comma-delimited text format.
This makes it more convenient to parse using standard Unix tools such as
grep in addition to full programming languages like Ruby or Python.
The format is:
Each component is explained below:
timestampis a Unix timestamp in UTC of when the message was printed.
targetWhen you call
packer buildthis can be either empty or individual build names, e.g.
amazon-ebs. It is normally empty when builds are in progress, and the build name when artifacts of particular builds are being referred to.
typeis the type of machine-readable message being outputted. The two most common
datais zero or more comma-separated values associated with the prior type. The exact amount and meaning of this data is type-dependent, so you must read the documentation associated with the type to understand fully.
Within the format, if data contains a comma, it is replaced with
%!(PACKER_COMMA). This was preferred over an escape character such as
because it is more friendly to tools like
Newlines within the format are replaced with their respective standard escape
sequence. Newlines become a literal
\n within the output. Carriage returns
become a literal
Here's an incomplete list of types you may see in the machine-readable output:
You'll see these data types when you run
ui: this means that the information being provided is a human-readable string that would be sent to stdout even if we aren't in machine-readable mode. There are three "data" subtypes associated with this type:
artifact-count: This data type tells you how many artifacts a particular build produced.
artifact: This data type tells you information about what Packer created during its build. An example of output follows the pattern
timestamp, buildname, artifact, artifact_number, key, valuewhere
valuecontain information about the artifact.
1539967803,,ui,say,\n==> Builds finished. The artifacts of successful builds are: 1539967803,amazon-ebs,artifact-count,2 1539967803,amazon-ebs,artifact,0,builder-id,mitchellh.amazonebs 1539967803,amazon-ebs,artifact,0,id,eu-west-1:ami-04d23aca8bdd36e30 1539967803,amazon-ebs,artifact,0,string,AMIs were created:\neu-west-1: ami-04d23aca8bdd36e30\n 1539967803,amazon-ebs,artifact,0,files-count,0 1539967803,amazon-ebs,artifact,0,end 1539967803,,ui,say,--> amazon-ebs: AMIs were created:\neu-west-1: ami-04d23aca8bdd36e30\n 1539967803,amazon-ebs,artifact,1,builder-id, 1539967803,amazon-ebs,artifact,1,id, 1539967803,amazon-ebs,artifact,1,string, 1539967803,amazon-ebs,artifact,1,files-count,0 2018/10/19 09:50:03 waiting for all plugin processes to complete... 1539967803,amazon-ebs,artifact,1,end
You'll see these data types when you run
version: what version of Packer is running
version-prerelease: Data will contain
devif version is prerelease, and otherwise will be blank.
version-commit: The git hash for the commit that the branch of Packer is currently on; most useful for Packer developers.
packer command features opt-in subcommand autocompletion that you can
enable for your shell with
packer -autocomplete-install. After doing so, you
can invoke a new shell and use the feature.
For example, assume a tab is typed at the end of each prompt line:
$ packer p plugin build $ packer build - -color -debug -except -force -machine-readable -on-error -only -parallel -timestamp -var -var-file