Formatting a Packer Template in HCL2

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Formatting a Packer Template in HCL2

Packer allows us to create templates for generating cross-platform machine images, and HashiCorp provides its own configuration language for this task. In this lab, we'll test our HCL2 skills by fixing and otherwise neaten up an inaccurately written HCL2 Packer template. Just want to test your HCL2 reviewing skills? No Packer knowledge is needed to take this lab.

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Lab Info

Level

Beginner

Last updated

Aug 24, 2025

Duration

30m

Challenge

Fix Whitespace

Open the provided template:
```
cd packer
```
```
vim ami-test.pkr.hcl
```

To make viewing the template easier, let's neaten up the template by adjusting the tabs/whitespace:

source "amazon-ebs" "ubuntu-ami-test": {
    access_key = "",
    secret_key = "",
    security_group_ids = [""],
    subnet_id = "",
    region = "us-east-1",
    ami_name = "ubuntu-ami-test_{{timestamp}}",
    instance_type = "t2.micro",
    source_ami = "ami-068663a3c619dd892",
    communicator = "ssh",
    ssh_username = "ubuntu"
}

build {
    sources = [ "source.amazon-ebs.ubuntu-ami-test" ]

    provisioner "shell" [
        script = "init.sh"
    ]
}

Challenge

Adjust Structural Errors

Update the template to remove the unnecessary colon (:) in the initial source block. The provisioner block also needs to be updated to work as an object not an array:

source "amazon-ebs" "ubuntu-ami-test" {
    access_key = "",
    secret_key = "",
    security_group_ids = [""],
    subnet_id = "",
    region = "us-east-1",
    ami_name = "ubuntu-ami-test_{{timestamp}}",
    instance_type = "t2.micro",
    source_ami = "ami-068663a3c619dd892",
    communicator = "ssh",
    ssh_username = "ubuntu"
}

build {
    sources = [ "source.amazon-ebs.ubuntu-ami-test" ]

    provisioner "shell" {
        script = "init.sh"
    }
}

Finally, remove any commas:

source "amazon-ebs" "ubuntu-ami-test" {
    access_key = ""
    secret_key = ""
    security_group_ids = [""]
    subnet_id = ""
    region = "us-east-1"
    ami_name = "ubuntu-ami-test_{{timestamp}}"
    instance_type = "t2.micro"
    source_ami = "ami-068663a3c619dd892"
    communicator = "ssh"
    ssh_username = "ubuntu"
}

build {
    sources = [ "source.amazon-ebs.ubuntu-ami-test" ]

    provisioner "shell" {
        script = "init.sh"
    }
}

Challenge

Run the Build
1. Using the credentials on the hands-on lab page, update the variables to use the provided access key, secret key, subnet ID, and security group.
2. Save and exit the file.
3. Run the build:
  
  packer build .

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