diff --git a/builder/docker/config.go b/builder/docker/config.go
index 20feb885b..b37d63d0c 100644
--- a/builder/docker/config.go
+++ b/builder/docker/config.go
@@ -26,67 +26,80 @@ type Config struct {
 	common.PackerConfig `mapstructure:",squash"`
 	Comm                communicator.Config `mapstructure:",squash"`
 
-	Author  string
-	Changes []string
-	Commit  bool
-	// The directory inside container to mount temp
-	// directory from host server for work file
-	// provisioner. This defaults to
-	// c:/packer-files on windows and /packer-files on other systems.
+	// Set the author (e-mail) of a commit.
+	Author string `mapstructure:"author"`
+	// Dockerfile instructions to add to the commit. Example of instructions
+	// are CMD, ENTRYPOINT, ENV, and EXPOSE. Example: [ "USER ubuntu", "WORKDIR
+	// /app", "EXPOSE 8080" ]
+	Changes []string `mapstructure:"changes"`
+	// If true, the container will be committed to an image rather than exported.
+	Commit bool `mapstructure:"commit" required:"true"`
+
+	// The directory inside container to mount temp directory from host server
+	// for work file provisioner. This defaults to c:/packer-files on windows
+	// and /packer-files on other systems.
 	ContainerDir string `mapstructure:"container_dir" required:"false"`
-	Discard      bool
-	// Username (UID) to run remote commands with. You can
-	// also set the group name/ID if you want: (UID or UID:GID).
-	// You may need this if you get permission errors trying to run the shell or
-	// other provisioners.
-	ExecUser   string `mapstructure:"exec_user" required:"false"`
-	ExportPath string `mapstructure:"export_path"`
-	Image      string
-	Message    string
-	// If true, run the docker container with the
-	// --privileged flag. This defaults to false if not set.
+	// Throw away the container when the build is complete. This is useful for
+	// the [artifice
+	// post-processor](https://www.packer.io/docs/post-processors/artifice.html).
+	Discard bool `mapstructure:"discard" required:"true"`
+	// Username (UID) to run remote commands with. You can also set the group
+	// name/ID if you want: (UID or UID:GID). You may need this if you get
+	// permission errors trying to run the shell or other provisioners.
+	ExecUser string `mapstructure:"exec_user" required:"false"`
+	// The path where the final container will be exported as a tar file.
+	ExportPath string `mapstructure:"export_path" required:"true"`
+	// The base image for the Docker container that will be started. This image
+	// will be pulled from the Docker registry if it doesn't already exist.
+	Image string `mapstructure:"image" required:"true"`
+	// Set a message for the commit.
+	Message string `mapstructure:"message" required:"true"`
+	// If true, run the docker container with the `--privileged` flag. This
+	// defaults to false if not set.
 	Privileged bool `mapstructure:"privileged" required:"false"`
 	Pty        bool
-	Pull       bool
-	// An array of arguments to pass to
-	// docker run in order to run the container. By default this is set to
-	// ["-d", "-i", "-t", "--entrypoint=/bin/sh", "--", "{{.Image}}"] if you are
-	// using a linux container, and
-	// ["-d", "-i", "-t", "--entrypoint=powershell", "--", "{{.Image}}"] if you
-	// are running a windows container. {{.Image}} is a template variable that
-	// corresponds to the image template option. Passing the entrypoint option
-	// this way will make it the default entrypoint of the resulting image, so
-	// running docker run -it --rm  will start the docker image from the
-	// /bin/sh shell interpreter; you could run a script or another shell by
-	// running docker run -it --rm  -c /bin/bash. If your docker image
-	// embeds a binary intended to be run often, you should consider changing the
-	// default entrypoint to point to it.
+	// If true, the configured image will be pulled using `docker pull` prior
+	// to use. Otherwise, it is assumed the image already exists and can be
+	// used. This defaults to true if not set.
+	Pull bool `mapstructure:"pull" required:"false"`
+	// An array of arguments to pass to docker run in order to run the
+	// container. By default this is set to ["-d", "-i", "-t",
+	// "--entrypoint=/bin/sh", "--", "{{.Image}}"] if you are using a linux
+	// container, and ["-d", "-i", "-t", "--entrypoint=powershell", "--",
+	// "{{.Image}}"] if you are running a windows container. {{.Image}} is a
+	// template variable that corresponds to the image template option. Passing
+	// the entrypoint option this way will make it the default entrypoint of
+	// the resulting image, so running docker run -it --rm  will start the
+	// docker image from the /bin/sh shell interpreter; you could run a script
+	// or another shell by running docker run -it --rm  -c /bin/bash. If your
+	// docker image embeds a binary intended to be run often, you should
+	// consider changing the default entrypoint to point to it.
 	RunCommand []string `mapstructure:"run_command" required:"false"`
-	Volumes    map[string]string
-	// If true, files uploaded to the container
-	// will be owned by the user the container is running as. If false, the owner
-	// will depend on the version of docker installed in the system. Defaults to
-	// true.
+	// A mapping of additional volumes to mount into this container. The key of
+	// the object is the host path, the value is the container path.
+	Volumes map[string]string `mapstructure:"volumes" required:"false"`
+	// If true, files uploaded to the container will be owned by the user the
+	// container is running as. If false, the owner will depend on the version
+	// of docker installed in the system. Defaults to true.
 	FixUploadOwner bool `mapstructure:"fix_upload_owner" required:"false"`
-	// If "true", tells Packer that you are building a
-	// Windows container running on a windows host. This is necessary for building
-	// Windows containers, because our normal docker bindings do not work for them.
+	// If "true", tells Packer that you are building a Windows container
+	// running on a windows host. This is necessary for building Windows
+	// containers, because our normal docker bindings do not work for them.
 	WindowsContainer bool `mapstructure:"windows_container" required:"false"`
 
 	// This is used to login to dockerhub to pull a private base container. For
 	// pushing to dockerhub, see the docker post-processors
-	Login bool
+	Login bool `mapstructure:"login" required:"false"`
 	// The password to use to authenticate to login.
 	LoginPassword string `mapstructure:"login_password" required:"false"`
 	// The server address to login to.
 	LoginServer string `mapstructure:"login_server" required:"false"`
 	// The username to use to authenticate to login.
 	LoginUsername string `mapstructure:"login_username" required:"false"`
-	// Defaults to false. If true, the builder will login
-	// in order to pull the image from Amazon EC2 Container Registry
-	// (ECR). The builder only logs in for the
-	// duration of the pull. If true login_server is required and login,
-	// login_username, and login_password will be ignored. For more
+	// Defaults to false. If true, the builder will login in order to pull the
+	// image from Amazon EC2 Container Registry (ECR). The builder only logs in
+	// for the duration of the pull. If true login_server is required and
+	// login, login_username, and login_password will be ignored. For more
 	// information see the section on ECR.
 	EcrLogin        bool `mapstructure:"ecr_login" required:"false"`
 	AwsAccessConfig `mapstructure:",squash"`
@@ -125,7 +138,7 @@ func NewConfig(raws ...interface{}) (*Config, []string, error) {
 	// Default Pull if it wasn't set
 	hasPull := false
 	for _, k := range md.Keys {
-		if k == "Pull" {
+		if k == "pull" {
 			hasPull = true
 			break
 		}