Built-in Functions

Complete list of available functions.

function-hcl supports most Terraform functions as of v1.5.7. Exceptions are noted at the end of the page.

Available Functions by Category

Function	Description
`abs(n)`	Absolute value
`ceil(n)`	Round up to nearest integer
`floor(n)`	Round down to nearest integer
`log(n, base)`	Logarithm
`max(n1, n2, ...)`	Maximum value
`min(n1, n2, ...)`	Minimum value
`parseint(str, base)`	Parse integer from string
`pow(base, exp)`	Exponentiation
`signum(n)`	Sign of number (-1, 0, 1)

Function	Description
`chomp(str)`	Remove trailing newlines
`endswith(str, suffix)`	Check suffix
`format(fmt, args...)`	String formatting (sprintf-style)
`formatlist(fmt, list...)`	Format each element
`indent(spaces, str)`	Indent all lines
`join(sep, list)`	Join list elements
`lower(str)`	Lowercase
`regex(pattern, str)`	Regex match
`regexall(pattern, str)`	All regex matches
`replace(str, old, new)`	String replacement
`split(sep, str)`	Split string
`startswith(str, prefix)`	Check prefix
`strrev(str)`	Reverse string
`substr(str, offset, length)`	Substring
`title(str)`	Title case
`trim(str, chars)`	Trim characters
`trimprefix(str, prefix)`	Trim prefix
`trimsuffix(str, suffix)`	Trim suffix
`trimspace(str)`	Trim whitespace
`upper(str)`	Uppercase

Function	Description
`alltrue(list)`	All elements are true
`anytrue(list)`	Any element is true
`chunklist(list, size)`	Split list into chunks
`coalesce(vals...)`	First non-null, non-empty value
`coalescelist(lists...)`	First non-empty list
`compact(list)`	Remove empty strings
`concat(lists...)`	Concatenate lists
`contains(list, val)`	Check membership
`distinct(list)`	Remove duplicates
`element(list, idx)`	Get element by index (wraps)
`flatten(list)`	Flatten nested lists
`index(list, val)`	Find index of value
`keys(map)`	Map keys
`length(val)`	Length of string, list, or map
`list(vals...)`	Create a list
`lookup(map, key, default)`	Safe map lookup
`map(k1, v1, k2, v2, ...)`	Create a map
`matchkeys(vals, keys, search)`	Filter by matching keys
`merge(maps...)`	Merge maps
`one(list)`	Extract single element or null
`range(start, limit, step)`	Generate number sequence
`reverse(list)`	Reverse list
`setintersection(sets...)`	Set intersection
`setproduct(sets...)`	Cartesian product
`setsubtract(a, b)`	Set difference
`setunion(sets...)`	Set union
`slice(list, start, end)`	List slice
`sort(list)`	Sort strings lexicographically
`sum(list)`	Sum numbers
`transpose(map)`	Transpose map of lists
`values(map)`	Map values
`zipmap(keys, values)`	Create map from key/value lists

Function	Description
`base64decode(str)`	Decode base64
`base64encode(str)`	Encode to base64
`base64gzip(str)`	Gzip then base64 encode
`csvdecode(str)`	Parse CSV
`jsondecode(str)`	Parse JSON
`jsonencode(val)`	Encode to JSON
`textdecodebase64(str, enc)`	Decode base64 with encoding
`textencodebase64(str, enc)`	Encode with encoding then base64
`urlencode(str)`	URL encode
`yamldecode(str)`	Parse YAML
`yamlencode(val)`	Encode to YAML

Function	Description
`cidrhost(prefix, hostnum)`	Calculate host IP
`cidrnetmask(prefix)`	Network mask
`cidrsubnet(prefix, newbits, netnum)`	Calculate subnet
`cidrsubnets(prefix, newbits...)`	Calculate multiple subnets

Function	Description
`can(expr)`	Test if expression evaluates without error
`nonsensitive(val)`	Remove sensitive marking
`sensitive(val)`	Mark as sensitive
`tobool(val)`	Convert to bool
`tolist(val)`	Convert to list
`tomap(val)`	Convert to map
`tonumber(val)`	Convert to number
`toset(val)`	Convert to set
`tostring(val)`	Convert to string
`try(exprs...)`	First expression that doesn’t error
`type(val)`	Get type of value

invoke("functionName", { arg1: value1, arg2: value2 })

Calls a user-defined function. The first argument must be a static string. See the language guide for details.

function-hcl is a memory-only system with no filesystem access:

file, fileexists, fileset, filebase64, templatefile, abspath, pathexpand, basename, dirname

These introduce non-determinism. function-hcl is designed to be hermetic – the same inputs always produce the same outputs:

uuid, uuidv5, timestamp, plantimestamp, bcrypt