website/content/docs/templates/legacy_json_templates/communicator.mdx
⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️
[!IMPORTANT]
Documentation Update: Product documentation previously located in/websitehas moved to thehashicorp/web-unified-docsrepository, where all product documentation is now centralized. Please make contributions directly toweb-unified-docs, since changes to/websitein this repository will not appear on developer.hashicorp.com. ⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️⚠️
This topic describes how to use communicators in Packer templates written in JSON format.
@include 'from-1.5/legacy-json-warning.mdx'
Packer uses communicators to upload files, execute scripts, and perform other actions on the machine being created. Configure communicators in the
builder section.
All communicators have the following options:
@include 'packer-plugin-sdk/communicator/Config-not-required.mdx'
Depending on your builder, your communicator may not have all it needs in order to work "out of the box".
If you are building from a cloud image (for example, building on Amazon), there is a good chance that your cloud provider has already preconfigured SSH on the image for you, meaning that all you have to do is configure the communicator in the Packer template.
However, if you are building from a brand-new and unconfigured operating system image, you will almost always have to perform some extra work to configure SSH on the guest machine. For most operating system distributions, this work will be performed by a boot_command that references a file which provides answers to the normally-interactive questions you get asked when installing an operating system. The name of this file varies by operating system; some common examples are the "preseed" file required by Debian, the "kickstart" file required by CentOS or the "answer file", also known as the Autounattend.xml file, required by Windows. For simplicity's sake, we'll refer to this file as the "preseed" file in the rest of the documentation.
If you are unfamiliar with how to use a preseed file for automatic bootstrapping of an image, please either take a look at our quick guides to image bootstrapping, or research automatic configuration for your specific guest operating system. Knowing how to automatically initalize your operating system is critical for being able to successfully use Packer.
For more details on how to use each communicator, visit the communicators page.