Functions · Glazier

Every attribute value in a profile is an HCL expression, so you get interpolation, for comprehensions and a small function library for free. The functions are thin wrappers around the go-cty standard library, the same library Terraform uses, plus one of my own called random. The library is deliberately small. If you need a function that is not here, the profile is probably doing a job a shell script should do.

Expressions

An expression has access to this context:

Form	Meaning
`var.<name>`	A declared variable. See Variables.
`local.<name>`	A resolved local. See Locals.
`env.<name>`	The environment variable `GLAZE_ENV_<name>`.
`path.pwd`, `path.base`	The current directory and its basename.
`"gig-${var.district}"`	String interpolation.
`[for e in local.editors : upper(e)]`	A native HCL `for` expression.

A ${...} wrapper is necessary only when you splice a value into a larger string. starting_directory = var.project uses the value directly.

Function library

Function	What it does
`chomp(string)`	Removes trailing newline characters.
`coalesce(values...)`	Returns the first argument that is not null. An empty string is not null, so `coalesce("", "x")` returns `""`.
`concat(lists...)`	Joins lists into one list.
`csvdecode(string)`	Parses CSV text into a list of objects.
`format(spec, values...)`	Formats a string in the style of `printf`.
`join(separator, list)`	Joins the elements of a list into one string.
`jsondecode(string)`	Parses JSON text into a value.
`len(collection)`	Counts the elements of a collection.
`lower(string)`	Converts a string to lower case.
`random(list)`	Returns one random element of a list as a string. See below.
`regexreplace(string, pattern, replacement)`	Replaces each match of a regular expression.
`replace(string, search, replacement)`	Replaces each occurrence of a substring.
`reverse(string)`	Reverses the characters of a string.
`reverselist(list)`	Reverses the order of a list.
`split(separator, string)`	Splits a string into a list.
`strlen(string)`	Counts the characters of a string.
`substr(string, offset, length)`	Returns a part of a string.
`title(string)`	Converts the first letter of each word to upper case.
`trim(string, characters)`	Removes the given characters from both ends.
`trimprefix(string, prefix)`	Removes a prefix.
`trimspace(string)`	Removes white space from both ends.
`trimsuffix(string, suffix)`	Removes a suffix.
`upper(string)`	Converts a string to upper case.

Two pairs are easy to confuse:

len counts the elements of a collection. strlen counts the characters of a string.
reverse reverses the characters of a string. reverselist reverses the order of a list, for example reverselist(local.editors).

`random`

random(list) returns one element of a list, chosen at random, as a string.

Rule	Behaviour
Argument	A list, a tuple or a set. A map or an object is an error.
Empty list	An error.
Elements	Each element must convert to a string.
Result	A new choice on each run.
Session name	Not allowed in the session `name`, directly or through a local. See Session.

The function pairs naturally with a comprehension:

HCL
locals {
  greeting = random([for g in ["hello", "hey", "yo"] : title(g)])
}

session {
  name = "daemon-run"

  window {
    name = local.greeting

    pane {
      commands = ["echo ${random(["jacked in", "online", "breach ready"])}"]
    }
  }
}

Use random() in a window name, a pane name or a command. glaze down computes the session name again, so a random session name would send down after a session that does not exist.

The full behaviour of each standard function is in the go-cty stdlib documentation. Glazier does not change the arguments or the results.

Expressions#

Function library#

random#

Expressions

Function library

`random`