44 lines
1.7 KiB
Plaintext
44 lines
1.7 KiB
Plaintext
---
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page_title: Generating code for config spec.
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sidebar_title: Making a plugin HCL2 enabled
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description: Learn how to generate the HCL2 configuration of your component easily.
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---
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# Auto Generate the HCL2 code of a plugin
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From v1.5, Packer can be configured using HCL2. Because Packer has so many
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builders, provisioners, and post-processors, we created a on code generation
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tool to add the HCL2-enabling code more easily. You can use this code generator
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to create the HCL2 spec code of your custom plugin simply. It's a Go binary
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package and is located in
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[`cmd/mapstructure-to-hcl2`](https://github.com/hashicorp/packer/tree/master/cmd/mapstructure-to-hcl2).
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Say you want to configure the `Config` struct of a `Builder` in a package
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located in `my/example-plugin/config.go`. Here are some simple steps you can
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follow to make it HCL2 enabled:
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- run `go install github.com/hashicorp/packer/cmd/mapstructure-to-hcl2`
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- Add `//go:generate mapstructure-to-hcl2 -type Config` at the top of
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`config.go`
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- run `go generate ./my/example-plugin/...`
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This will generate a `my/example-plugin/config.hcl2spec.go` file containing
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the configuration fields of `Config`.
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- Make sure that all the nested structs of `Config` are also auto generated the
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same way.
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- Now we only need to make your Builder implement the interface by adding the
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following snippet:
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```go
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func (b *Builder) ConfigSpec() hcldec.ObjectSpec { return b.config.FlatMapstructure().HCL2Spec() }
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```
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From now on every time you add or change a field of Config you will need to
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run the `go generate` command again.
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A good example of this is the [Config struct of the amazon-ebs builder](https://github.com/hashicorp/packer/blob/master/builder/amazon/ebs/builder.go)
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