vendor/github.com/hashicorp/terraform/helper/resource/id.go

   1 package resource
   2
   3 import (
   4         "fmt"
   5         "strings"
   6         "sync"
   7         "time"
   8 )
   9
  10 const UniqueIdPrefix = `terraform-`
  11
  12 // idCounter is a monotonic counter for generating ordered unique ids.
  13 var idMutex sync.Mutex
  14 var idCounter uint32
  15
  16 // Helper for a resource to generate a unique identifier w/ default prefix
  17 func UniqueId() string {
  18         return PrefixedUniqueId(UniqueIdPrefix)
  19 }
  20
  21 // UniqueIDSuffixLength is the string length of the suffix generated by
  22 // PrefixedUniqueId. This can be used by length validation functions to
  23 // ensure prefixes are the correct length for the target field.
  24 const UniqueIDSuffixLength = 26
  25
  26 // Helper for a resource to generate a unique identifier w/ given prefix
  27 //
  28 // After the prefix, the ID consists of an incrementing 26 digit value (to match
  29 // previous timestamp output).  After the prefix, the ID consists of a timestamp
  30 // and an incrementing 8 hex digit value The timestamp means that multiple IDs
  31 // created with the same prefix will sort in the order of their creation, even
  32 // across multiple terraform executions, as long as the clock is not turned back
  33 // between calls, and as long as any given terraform execution generates fewer
  34 // than 4 billion IDs.
  35 func PrefixedUniqueId(prefix string) string {
  36         // Be precise to 4 digits of fractional seconds, but remove the dot before the
  37         // fractional seconds.
  38         timestamp := strings.Replace(
  39                 time.Now().UTC().Format("20060102150405.0000"), ".", "", 1)
  40
  41         idMutex.Lock()
  42         defer idMutex.Unlock()
  43         idCounter++
  44         return fmt.Sprintf("%s%s%08x", prefix, timestamp, idCounter)
  45 }