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.
For more details on how to use each communicator, click the links above to be taken to each communicator's page.