yq/usage/hcl.md

HCL

Encode and decode to and from HashiCorp Configuration Language (HCL).

HCL is commonly used in HashiCorp tools like Terraform for configuration files. The yq HCL encoder and decoder support:

• Blocks and attributes
• String interpolation and expressions (preserved without quotes)
• Comments (leading, head, and line comments)
• Nested structures (maps and lists)
• Syntax colorization when enabled

Parse HCL

Given a sample.hcl file of:

io_mode = "async"

then

yq -oy sample.hcl

will output

io_mode: "async"

Roundtrip: Sample Doc

Given a sample.hcl file of:

service "cat" {
  process "main" {
    command = ["/usr/local/bin/awesome-app", "server"]
  }

  process "management" {
    command = ["/usr/local/bin/awesome-app", "management"]
  }
}

then

yq sample.hcl

will output

service "cat" {
  process "main" {
    command = ["/usr/local/bin/awesome-app", "server"]
  }
  process "management" {
    command = ["/usr/local/bin/awesome-app", "management"]
  }
}

Roundtrip: With an update

Given a sample.hcl file of:

service "cat" {
  process "main" {
    command = ["/usr/local/bin/awesome-app", "server"]
  }

  process "management" {
    command = ["/usr/local/bin/awesome-app", "management"]
  }
}

then

yq '.service.cat.process.main.command += "meow"' sample.hcl

will output

service "cat" {
  process "main" {
    command = ["/usr/local/bin/awesome-app", "server", "meow"]
  }
  process "management" {
    command = ["/usr/local/bin/awesome-app", "management"]
  }
}

Parse HCL: Sample Doc

Given a sample.hcl file of:

service "cat" {
  process "main" {
    command = ["/usr/local/bin/awesome-app", "server"]
  }

  process "management" {
    command = ["/usr/local/bin/awesome-app", "management"]
  }
}

then

yq -oy sample.hcl

will output

service:
  cat:
    process:
      main:
        command:
          - "/usr/local/bin/awesome-app"
          - "server"
      management:
        command:
          - "/usr/local/bin/awesome-app"
          - "management"

Parse HCL: with comments

Given a sample.hcl file of:

# Configuration
port = 8080 # server port

then

yq -oy sample.hcl

will output

# Configuration
port: 8080 # server port

Roundtrip: with comments

Given a sample.hcl file of:

# Configuration
port = 8080

then

yq sample.hcl

will output

# Configuration
port = 8080

Roundtrip: With templates, functions and arithmetic

Given a sample.hcl file of:

# Arithmetic with literals and application-provided variables
sum = 1 + addend

# String interpolation and templates
message = "Hello, ${name}!"

# Application-provided functions
shouty_message = upper(message)

then

yq sample.hcl

will output

# Arithmetic with literals and application-provided variables
sum = 1 + addend
# String interpolation and templates
message = "Hello, ${name}!"
# Application-provided functions
shouty_message = upper(message)

Roundtrip: Separate blocks with same name.

Given a sample.hcl file of:

resource "aws_instance" "web" {
  ami = "ami-12345"
}
resource "aws_instance" "db" {
  ami = "ami-67890"
}

then

yq sample.hcl

will output

resource "aws_instance" "web" {
  ami = "ami-12345"
}
resource "aws_instance" "db" {
  ami = "ami-67890"
}