packer-cn/website/content/guides/workflow-tips-and-tricks/use-packer-with-comment.mdx

---
page_title: Use jq and Packer to comment your templates - Guides
sidebar_title: Use jq to strip comments from a Packer template
description: |-
  You can add detailed comments beyond the root-level underscore-prefixed field
  supported by Packer, and remove them using jq.
---

# How to use jq to strip unsupported comments from a Packer template


-> **Note:** Packer supports HCL2 from version 1.6.0, the Hashicorp Configuration
Language allows to comment directly in template files. Consider upgrading your
JSON template to HCL2 using the `packer hcl2_upgrade` command.

One of the biggest complaints we get about Packer is that JSON doesn't use comments.
For Packer JSON templates, you can add detailed comments beyond the root-level underscore-prefixed field supported by Packer, and remove them using jq.

Let's say we have a file named `commented_template.json`

```json
{
  "_comment": ["this is", "a multi-line", "comment"],
  "builders": [
    {
      "_comment": "this is a comment inside a builder",
      "type": "null",
      "communicator": "none"
    }
  ],
  "_comment": "this is a root level comment",
  "provisioners": [
    {
      "_comment": "this is a different comment",
      "type": "shell",
      "_comment": "this is yet another comment",
      "inline": ["echo hellooooo"]
    }
  ]
}
```

```shell-session
$ jq 'walk(if type == "object" then del(._comment) else . end)' commented_template.json > uncommented_template.json
```

will produce a new file containing:

```json
{
  "builders": [
    {
      "type": "null",
      "communicator": "none"
    }
  ],
  "provisioners": [
    {
      "type": "shell",
      "inline": ["echo hellooooo"]
    }
  ]
}
```

Once you've got your uncommented file, you can call `packer build` on it like
you normally would.

## The walk function

If your install of jq does not have the walk function and you get an error like

```text
jq: error: walk/1 is not defined at <top-level>,
```

You can create a file `~/.jq` and add the [walk function](https://github.com/stedolan/jq/blob/ad9fc9f559e78a764aac20f669f23cdd020cd943/src/builtin.jq#L255-L262) to it by hand.