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Communicators are the mechanism Packer uses to upload files, execute scripts, etc. with the machine being created.	docs	Communicators - Templates	docs-templates-communicators

Template Communicators

Communicators are the mechanism Packer uses to upload files, execute scripts, etc. with the machine being created.

Communicators are configured within the builder section. Packer currently supports three kinds of communicators:

• none - No communicator will be used. If this is set, most provisioners also can't be used.

• ssh - An SSH connection will be established to the machine. This is usually the default.

• winrm - A WinRM connection will be established.

In addition to the above, some builders have custom communicators they can use. For example, the Docker builder has a "docker" communicator that uses docker exec and docker cp to execute scripts and copy files.

Using a Communicator

By default, the SSH communicator is usually used. Additional configuration may not even be necessary, since some builders such as Amazon automatically configure everything.

However, to specify a communicator, you set the communicator key within a build. Multiple builds can have different communicators. Example:

{
  "builders": [
    {
      "type": "amazon-ebs",
      "communicator": "ssh"
    }
  ]
}

After specifying the communicator, you can specify a number of other configuration parameters for that communicator. These are documented below.

SSH Communicator

The SSH communicator connects to the host via SSH. If you have an SSH agent enabled on the machine running Packer, it will automatically forward the SSH agent to the remote host.

The SSH communicator has the following options:

• ssh_bastion_agent_auth (boolean) - If true, the local SSH agent will be used to authenticate with the bastion host. Defaults to false.

• ssh_bastion_host (string) - A bastion host to use for the actual SSH connection.

• ssh_bastion_password (string) - The password to use to authenticate with the bastion host.

• ssh_bastion_port (integer) - The port of the bastion host. Defaults to 1.

• ssh_bastion_private_key_file (string) - A private key file to use to authenticate with the bastion host.

• ssh_bastion_username (string) - The username to connect to the bastion host.

• ssh_disable_agent_forwarding (boolean) - If true, SSH agent forwarding will be disabled. Defaults to false.

• ssh_file_transfer_method (scp or sftp) - How to transfer files, Secure copy (default) or SSH File Transfer Protocol.

• ssh_handshake_attempts (integer) - The number of handshakes to attempt with SSH once it can connect. This defaults to 10.

• ssh_host (string) - The address to SSH to. This usually is automatically configured by the builder.

• ssh_password (string) - A plaintext password to use to authenticate with SSH.

• ssh_port (integer) - The port to connect to SSH. This defaults to 22.

• ssh_private_key_file (string) - Path to a PEM encoded private key file to use to authentiate with SSH.

• ssh_pty (boolean) - If true, a PTY will be requested for the SSH connection. This defaults to false.

• ssh_timeout (string) - The time to wait for SSH to become available. Packer uses this to determine when the machine has booted so this is usually quite long. Example value: "10m"

• ssh_username (string) - The username to connect to SSH with. Required if using SSH.

WinRM Communicator

The WinRM communicator has the following options.

• winrm_host (string) - The address for WinRM to connect to.

• winrm_port (integer) - The WinRM port to connect to. This defaults to 5985 for plain unencrypted connection and 5986 for SSL when winrm_use_ssl is set to true.

• winrm_username (string) - The username to use to connect to WinRM.

• winrm_password (string) - The password to use to connect to WinRM.

• winrm_timeout (string) - The amount of time to wait for WinRM to become available. This defaults to "30m" since setting up a Windows machine generally takes a long time.

• winrm_use_ssl (boolean) - If true, use HTTPS for WinRM

• winrm_insecure (boolean) - If true, do not check server certificate chain and host name

• winrm_use_ntlm (boolean) - If true, NTLM authentication will be used for WinRM, rather than default (basic authentication), removing the requirement for basic authentication to be enabled within the target guest. Further reading for remote connection authentication can be found here.