5ba134ac5b
hcl2_upgrade transforms a JSON build-file in a HCL2 build-file. This starts a validated Packer core and from that core we generate an HCL 'block' per plugin/configuration. So for a builder, a provisioner, a post-processor or a variable. The contents of each block is just transformed as is and basically all fields are HCL2-ified. A generated field can be valid in JSON but invalid on HCL2; for example JSON templating (in mapstructure) allows to set arrays of strings - like `x = ["a", "b"]` - with single strings - like `x="a"` -, HCL does not allow this. Since JSON does not make the distinction between variables and locals, everything will be a variable. So variables that use other variables will not work. hcl2_upgrade tries to transform go templating interpolation calls to HCL2 calls when possible, leaving the go templating calls like they are in case it cannot. Work: * transpiler * tests * update hcl v2 library so that output looks great. * update docs
81 lines
2.7 KiB
Plaintext
81 lines
2.7 KiB
Plaintext
---
|
|
description: |
|
|
The `packer hcl2_upgrade` Packer command is used to transpile a JSON
|
|
configuration template to it's formatted HCL2 counterpart. The command will
|
|
return a zero exit status on success, and a non-zero exit status on failure.
|
|
layout: docs
|
|
page_title: packer hcl2_upgrade - Commands
|
|
sidebar_title: <tt>hcl2_upgrade</tt>
|
|
---
|
|
|
|
-> **Note:** This command is Beta, and currently being improved upon; do not
|
|
hesitate [opening a new
|
|
issue](https://github.com/hashicorp/packer/issues/new/choose) if you find
|
|
something wrong.
|
|
|
|
# `hcl2_upgrade` Command
|
|
|
|
The `packer hcl2_upgrade` Packer command is used to transpile a JSON
|
|
configuration template to it's formatted HCL2 counterpart. The command will
|
|
return a zero exit status on success, and a non-zero exit status on failure.
|
|
|
|
Example usage:
|
|
|
|
```shell-session
|
|
$ packer hcl2_upgrade my-template.json
|
|
|
|
Successfully created my-template.json.pkr.hcl
|
|
```
|
|
|
|
## User variables using other user variables
|
|
|
|
Packer JSON recently started allowing using user variables from variables. In
|
|
HCL2, input variables cannot use functions nor other variables and are
|
|
virtually static, local variables must be used instead to craft more dynamic
|
|
variables. For that reason `hcl2_upgrade` cannot decide for you what local
|
|
variables to create and the `hcl2_upgrade` command will simply output all seen
|
|
variables as an input variable, it is now up to you to create a local variable.
|
|
|
|
Here is an example of a local variable using a string input variables:
|
|
|
|
```hcl
|
|
variable "foo" {
|
|
default = "Hello,"
|
|
}
|
|
|
|
variable "bar" {
|
|
default = "World!"
|
|
}
|
|
|
|
locals {
|
|
baz = "${var.foo} ${var.bar}"
|
|
}
|
|
```
|
|
|
|
## Go template functions
|
|
|
|
`hcl2_upgrade` will do its best to transform your go _template calls_ to HCL2,
|
|
here is the list of calls that should get transformed:
|
|
- ```{{ user `my_var` }}``` becomes ```${var.my_var}```.
|
|
- ```{{ env `my_var` }}``` becomes ```${var.my_var}```. Packer HCL2 supports
|
|
environment variables through input variables. See
|
|
[docs](http://packer.io/docs/from-1.5/variables#environment-variables)
|
|
for more info.
|
|
- ```{{ timestamp }}``` becomes ```${local.timestamp}```, the local variable
|
|
will be created for all generated files.
|
|
- ```{{ build `ID` }}``` becomes ```${build.ID}```.
|
|
|
|
The rest of the calls should remain go template calls for now, this will be
|
|
improved over time.
|
|
|
|
-> **Note**: The `hcl2_upgrade` command does its best to transform template
|
|
calls to their JSON counterpart, but it might fail. In that case the
|
|
`hcl2_upgrade` command will simply output the local HCL2 block without
|
|
transformation and with the error message in a comment. We are currently
|
|
working on improving this part of the transformer.
|
|
|
|
## Options
|
|
|
|
- `-output-file` - File where to put the hcl2 generated config. Defaults to
|
|
JSON_TEMPLATE.pkr.hcl
|