Terraform Built-in Functions

Terraform functions perform specific tasks on the data within the configuration files. OpenTofu has the same functions and a few more (see the OpenTofu functions). Try them with terraform console or tofu console, as shown in Terraform Tools. The functions list and map of older Terraform versions were removed: use tolist and tomap, or the literal syntax [ ] and { }.

Numeric Functions #

Perform mathematical operations like calculations, comparisons, and conversions on numbers.

• abs: Calculate absolute value.
• ceil: Round up to the nearest integer.
• floor: Round down to the nearest integer.
• log: Compute the logarithm of a number in a given base.
• max: Return the largest of the given numbers (use ... to expand a list).
• min: Return the smallest of the given numbers (use ... to expand a list).
• parseint: Parse a string as an integer in a given base.
• pow: Raise a number to a power.
• signum: Determine the sign of a number (-1, 0, or 1).

String Functions #

Manipulate text data, including formatting, searching, and transformations.

• chomp: Remove trailing newline characters.
• endswith: Check if a string ends with a specific substring.
• format: Apply formatting placeholders to a string.
• formatlist: Produce a list of strings by formatting each element of the given lists.
• indent: Add whitespace indentation to a string.
• join: Combine strings into a single string with a separator.
• lower: Convert all characters to lowercase.
• regex: Perform regular expression matching and extraction.
• regexall: Find all occurrences of a regular expression pattern.
• replace: Substitute one substring with another within a string.
• split: Divide a string into a list of substrings based on a delimiter.
• startswith: Check if a string starts with a specific substring.
• strcontains: Check if a substring is present within a string.
• strrev: Reverse the order of characters in a string.
• substr: Extract a specific substring from a string.
• title: Capitalize the first letter of each word in a string.
• trim: Remove the specified characters from the start and the end of a string.
• trimprefix: Remove a specific prefix from a string.
• trimsuffix: Remove a specific suffix from a string.
• trimspace: Remove leading and trailing whitespace from a string.
• upper: Convert all characters to uppercase.

Collection Functions #

Work with lists and maps, performing tasks like filtering, sorting, and aggregation.

• alltrue: Check if all elements in a list are true.
• anytrue: Check if any element in a list is true.
• chunklist: Divide a list into sublists of a specified size.
• coalesce: Return the first argument that is neither null nor an empty string.
• coalescelist: Return the first list that is not empty.
• compact: Remove empty strings from a list of strings.
• concat: Combine two or more lists into a single list (use merge for maps).
• contains: Check if a list contains a specific element.
• distinct: Remove duplicate elements from a list.
• element: Access a specific element within a list by index.
• flatten: Merge sublists within a list into a single, flat list.
• index: Find the position of an element within a list.
• keys: Extract the keys from a map.
• length: Get the number of elements in a list, map or set, or the length of a string.
• lookup: Access a specific value within a map by key.
• matchkeys: Select the values of a list by matching a second list of keys against a list of allowed keys.
• merge: Combine multiple maps into a single map, overriding conflicting keys.
• one: Extract the only element from a list, ensuring its length is 1.
• range: Generate a list of numbers in a specified range.
• reverse: Reverse the order of elements in a list.
• setintersection: Find the common elements between multiple sets.
• setproduct: Combine multiple sets by Cartesian product.
• setsubtract: Remove elements from one set that are present in another.
• setunion: Combine multiple sets into a single set, removing duplicates.
• slice: Extract a sublist from a list based on specific indices.
• sort: Sort a list of strings in lexicographical order.
• sum: Calculate the sum of all numeric elements in a list.
• transpose: Swap the keys and the values of a map of lists of strings.
• values: Extract the values from a map.
• zipmap: Combine two lists into a map, pairing elements at corresponding indices.

Encoding Functions #

Encode and decode data in different formats like base64, JSON, and YAML.

• base64decode: Decode base64-encoded data.
• base64encode: Encode data in base64 format.
• base64gzip: Compress and encode data with base64.
• csvdecode: Decode comma-separated values (CSV) data into a list of maps.
• jsondecode: Decode a JSON string into a value (object, list or primitive).
• jsonencode: Encode any value as a JSON string.
• textdecodebase64: Decode base64-encoded text data.
• textencodebase64: Encode text data in base64 format.
• urlencode: Encode a string for safe inclusion in URLs.
• yamldecode: Decode a YAML string into a value.
• yamlencode: Encode any value as a YAML string.

File System Functions #

Interact with files and directories, reading contents, checking existence, and manipulating paths.

• abspath: Get the absolute path of a file based on the current working directory.
• dirname: Extract the directory part of a file path.
• pathexpand: Expand a leading tilde (~) in a file path to the home directory of the current user.
• basename: Extract the last element of a file path (the file name, including its extension).
• file: Read the contents of a file as a string.
• fileexists: Check if a file exists at a specific path.
• fileset: Enumerate files within a directory based on patterns and glob.
• filebase64: Encode the contents of a file in base64 format.
• templatefile: Render a template file with embedded variables and interpolation.

Date and Time Functions #

Work with timestamps and dates, formatting them, adding durations, and comparing them.

• formatdate: Convert a timestamp to a string in a specific format.
• plantimestamp: Get the timestamp of the current Terraform plan execution.
• timeadd: Add a duration to a timestamp or time string.
• timecmp: Compare two timestamps or time strings for chronological order.
• timestamp: Return the current UTC date and time in RFC 3339 format.

Hash and Crypto Functions #

Generate secure hashes and cryptographic operations for data security.

• base64sha256: Generate a base64-encoded SHA-256 hash of data.
• base64sha512: Generate a base64-encoded SHA-512 hash of data.
• bcrypt: Generate a password hash using bcrypt algorithm.
• filebase64sha256: Calculate the base64-encoded SHA-256 hash of a file’s contents.
• filebase64sha512: Calculate the base64-encoded SHA-512 hash of a file’s contents.
• filemd5: Generate an MD5 hash of a file’s contents.
• filesha1: Generate an SHA-1 hash of a file’s contents.
• filesha256: Generate an SHA-256 hash of a file’s contents.
• filesha512: Generate an SHA-512 hash of a file’s contents.
• md5: Generate an MD5 hash of data.
• rsadecrypt: Decrypt data using RSA private key.
• sha1: Generate an SHA-1 hash of data.
• sha256: Generate an SHA-256 hash of data.
• sha512: Generate an SHA-512 hash of data.
• uuid: Generate a universally unique identifier (UUID).
• uuidv5: Generate a UUID based on a namespace and name.

IP Network Functions #

Work with CIDR blocks, extracting addresses, netmasks, and generating subnets.

• cidrhost: Calculate a full host IP address for a given host number within a CIDR block.
• cidrnetmask: Extract the netmask from a CIDR block.
• cidrsubnet: Divide a CIDR block into multiple subnets of a specified size.
• cidrsubnets: Calculate a sequence of consecutive subnets within a CIDR block.

Type Conversion #

Convert values between different data types like strings, numbers, and maps.

• can: Evaluate an expression and return true if it produces no error.
• nonsensitive: Remove the sensitive mark from a value, so it can be shown in the output.
• sensitive: Mark a value as sensitive, so it is hidden in the plan and in the output.
• tobool: Convert a value to a boolean (true or false).
• tolist: Convert a value to a list.
• tomap: Convert a value to a map.
• tonumber: Convert a value to a number.
• toset: Convert a value to a set.
• tostring: Convert a value to a string.
• try: Evaluate the expressions in order and return the result of the first one that does not produce an error.
• type: Return the type of a value (only available in terraform console).