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formatdate(format, time) formats time using the given format string. time must be an RFC 3339 timestamp string.

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Signature

formatdate(format string, time string) string

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Format tokens

TokenDescriptionExample
YYYYFour-digit year2024
YYTwo-digit year24
MMTwo-digit month01-12
MMMThree-letter month abbreviationJan
MMMMFull month nameJanuary
DDTwo-digit day01-31
DDay without leading zero1-31
hhTwo-digit hour (24-hour)00-23
mmTwo-digit minute00-59
ssTwo-digit second00-59
ZZZTimezone abbreviationUTC
ZTimezone offset+00:00

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Example

Stamp a release artifact with a timestamp passed in from the environment or CI system: 
variable "version" {
  type = string
}

variable "build_timestamp" {
  description = "RFC 3339 build timestamp (e.g. 2024-03-15T10:30:00Z)"
  type        = string
}

computed "release_date" {
  description = "Date portion of the build timestamp"
  expression  = formatdate("YYYY-MM-DD", var.build_timestamp)
}

task "package" {
  description = "Build a dated release archive"
  commands = [
    "go build -o bin/app ./cmd/app",
    "tar -czf releases/app-${var.version}-${computed.release_date}.tar.gz bin/app",
  ]
}
Pass the timestamp at run time: 
errand run package --var version=1.4.2 --var build_timestamp=2024-03-15T10:30:00Z
The archive name becomes app-1.4.2-2024-03-15.tar.gz.

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Notes

  • time must be a valid RFC 3339 string (e.g. 2024-03-15T10:30:00Z). An invalid format produces an error at evaluation time.
  • formatdate does not perform timezone conversion. The output timezone depends on the input timestamp.