---
description: |
  The `packer build` command takes a template and runs all the builds within it
  in order to generate a set of artifacts. The various builds specified within a
  template are executed in parallel, unless otherwise specified. And the
  artifacts that are created will be outputted at the end of the build.
page_title: packer build - Commands
---

# `build` Command

The `packer build` command takes a template and runs all the builds within it
in order to generate a set of artifacts. The various builds specified within a
template are executed in parallel, unless otherwise specified. And the
artifacts that are created will be outputted at the end of the build.

## Options

- `-color=false` - Disables colorized output. Enabled by default.

- `-debug` - Disables parallelization and enables debug mode. Debug mode
  flags the builders that they should output debugging information. The exact
  behavior of debug mode is left to the builder. In general, builders usually
  will stop between each step, waiting for keyboard input before continuing.
  This will allow the user to inspect state and so on.

`@include 'commands/except.mdx'`

- `-force` - Forces a builder to run when artifacts from a previous build
  prevent a build from running. The exact behavior of a forced build is left
  to the builder. In general, a builder supporting the forced build will
  remove the artifacts from the previous build. This will allow the user to
  repeat a build without having to manually clean these artifacts beforehand.

- `-on-error=cleanup` (default), `-on-error=abort`, `-on-error=ask`, `-on-error=run-cleanup-provisioner` -
  Selects what to do when the build fails during provisioning. Please note that
  this only affects the build during the provisioner run, not during the
  post-processor run, because it is related to whether or not to keep the
  instance running and related artifacts like generated SSH keys on the system
  when a provisioner fails.

  - `cleanup` cleans up after the previous steps, deleting temporary files and virtual machines.
  - `abort` exits without any cleanup, which might require the next build to use `-force`.
  - `ask` presents a prompt and waits for you to decide to clean up, abort, or retry
    the failed step.
  - `run-cleanup-provisioner` aborts and exits without any cleanup besides
    the [error-cleanup-provisioner](/packer/docs/templates/legacy_json_templates/provisioners#on-error-provisioner) if one is defined.

`@include 'commands/only.mdx'`

- `-parallel-builds=N` - Limit the number of builds to run in parallel, 0
  means no limit (defaults to 0).

- `-timestamp-ui` - Enable prefixing of each ui output with an RFC3339
  timestamp.

- `-var` - Set a variable in your Packer template. This option can be used
  multiple times. This is useful for setting version numbers for your build.

- `-var-file` - Set template variables from a file.

- `-warn-on-undeclared-var` - Setting this flag will yield a warning for each assignment within
  a variable definitions file (*.pkrvars.hcl | *.pkrvars.json) that does not have an accompanying
  variable block. This can occur when using a var-file that contains a large amount of unused variables
  for a given HCL2 template. For HCL2 template builds defining a value for a variable in a var-file is
  not enough on its own for Packer to function, as there also needs to be a variable block definition in
  the template files `pkr.hcl` for the variable. By default `packer build` will not warn when a var-file
  contains one or more undeclared variables.
