format

format(format, args...) produces a string by substituting values into a format template. It follows the same conventions as printf in most languages.

Signature

format(format string, args...) string

Format verbs

Verb	Description
`%s`	String
`%q`	JSON-quoted string
`%d`	Decimal integer
`%f`	Floating-point number
`%g`	Compact floating-point (removes trailing zeros)
`%G`	Compact floating-point (uppercase exponent)
`%e`	Scientific notation
`%E`	Scientific notation (uppercase)
`%x`	Hexadecimal (lowercase)
`%X`	Hexadecimal (uppercase)
`%b`	Binary
`%o`	Octal
`%t`	Boolean (`true` or `false`)
`%v`	Any value in a natural format
`%%`	Literal `%`

Example

Build a Docker image tag with zero-padded build numbers:

variable "build_number" {
  description = "CI build number"
  type        = number
}

variable "app" {
  type    = string
  default = "api"
}

computed "image_tag" {
  description = "Padded build tag for Docker image"
  expression  = format("%s-build-%04d", var.app, var.build_number)
}

task "build" {
  description = "Build the Docker image with a build-stamped tag"
  commands    = ["docker build -t myapp:${computed.image_tag} ."]
}

With build_number = 7, computed.image_tag becomes api-build-0007.

Notes

format is most useful when you need padding, alignment, or number formatting. For simple concatenation, string interpolation (${}) is more readable.
An incorrect number of arguments or incompatible types produce an error at evaluation time.

Overview

String

Number

Collection

Encoding

Crypto

Filesystem

Datetime

Regex

UUID

Conversion

Environment

Runtime

Signature

Format verbs

Example

Notes

​Signature

​Format verbs

​Example

​Notes

Signature

Format verbs

Example

Notes