Standard library overview

The Workflows standard library modules allow you to easily construct arguments for services and process responses. There is no need to import or load libraries in a workflow—library functions work out of the box.

All functions can be called using call steps, but only non-blocking functions can be used inside an expression. For example, HTTP calls, sys.sleep, and sys.log cannot be used inside an expression. For more information, see Blocking calls.

Workflows also includes frequently used functions, such as for data type and format conversions. See Expression helpers.

Generate random identifiers or numbers

You can use uuid.generate to return a random 128‑bit universally unique identifier (UUID) in string form.

You can use sys.now to generate multiple random numbers. (The function returns a floating point number with nanosecond precision.)

• If you need only one number, use sys.get_env to retrieve the workflow's execution identifier.

• If a unique ID is needed, you can use string() to convert the number returned from sys.now to a string and combine it with the execution ID; for example, some_execution_id1635892223.4459958.

Optionally, you can use a Cloud Run function to generate a number and call the Cloud Run function from your workflow.

Expression helpers

Built-in expression helper functions.

Conversion functions

Convert values from one data type to another.

Functions
double()	Accepts an attribute of type string or integer and returns a double.
int()	Accepts an attribute of type string or double and returns an integer.
string()	Accepts an attribute of type integer, double, or boolean and returns a string.

Data type functions

Operate on lists, maps, and strings.

Functions
in()	Checks whether a given key is present in a list or map.
keys()	Accepts an attribute of type map and returns a list of key elements in the map.
len()	Computes the length of value according to its type.

Conditional functions

Support conditions within expressions.

Functions
default(val, defaultVal)	Returns a value if it is not null; otherwise returns a default value.
if(condition, ifTrue, ifFalse)	Evaluates a condition and returns one of two arguments depending on what the condition evaluates to.

Type functions

Return data type.

Functions
get_type(arg)	Returns a string indicating the data type of the argument.

Module: base64

Base64 encoding/decoding.

Functions
decode	Decodes given Base64-encoded string to bytes.
encode	Encodes given bytes to Base64 text.

Module: events

Events support.

Functions
await_callback	Waits for a callback to be received at the given endpoint.
create_callback_endpoint	Creates a callback endpoint expecting the specified HTTP method.

Module: experimental.executions

Execution management.

Caution: The behavior of routines in this module might change, and they might not be supported in the future.

Instead of using experimental.executions.map to support parallel work, we recommend you execute workflow steps in parallel. If you are already using experimental.executions.map, you can migrate your workflow to use parallel steps.

Functions
execution_error	Raised when a workflow execution finishes with an error or is cancelled.
map	Starts workflow executions and waits for all of them to finish.
run	Starts a workflow execution and waits for it to finish.

Module: hash

Common hashing algorithms.

Functions
compute_checksum	Computes checksum using a given hashing algorithm.
compute_hmac	Computes the hash-based message authentication code (HMAC) for data given a secret key and hashing algorithm.

Module: http

HTTP/S request support.

Functions
default_retry_predicate	Simple default retry predicate for idempotent targets.
default_retry_predicate_non_idempotent	Simple default retry predicate for non-idempotent targets.
delete	Sends an HTTP DELETE request to the specified URL.
get	Sends an HTTP GET request to the specified URL.
patch	Sends an HTTP PATCH request to the specified URL.
post	Sends an HTTP POST request to the specified URL.
put	Sends an HTTP PUT request to the specified URL.
request	Sends an HTTP request.

Objects
default_retry	Simple default retry policy for idempotent targets.
default_retry_non_idempotent	Simple default retry policy for non-idempotent targets.

Module: json

JSON encoding/decoding.

Functions
decode	Decodes given JSON bytes (assuming UTF-8), or a string, into an object.
encode	Encodes given input object to JSON bytes, using UTF-8 charset.
encode_to_string	Encodes given object to a JSON string.

Module: list

List utility.

Functions
concat	Creates a copy of a list with a new element concatenated at the end.
prepend	Creates a copy of a list with a new element added to the beginning.

Module: map

Map utility.

Functions
delete	Takes a map, creates a copy of the map, and removes the item with the specified key.
get	Performs a safe lookup on a map, returning null if the key is not found.
merge	Takes two maps, creates a copy of the first map, and adds the items from the second map to the copy.
merge_nested	Takes two maps, creates a copy of the first map, and recursively adds items from the second map to the copy.

Module: math

Math utility.

Functions
abs	Returns the absolute value of a number.
floor	Returns the floor of a number.
max	Returns the maximum of two numbers.
min	Returns the minimum of two numbers.

Module: retry

Support for retries.

Functions
always	Convenience retry condition that retries on any error.
never	Convenience retry condition that retries on no error at all.

Objects
default_backoff	Simple default truncated exponential backoff policy.

Module: sys

Common system interface, with platform-dependent implementation.

Functions
get_env	Retrieves the value of the specified environment variable.
log	Writes one of data, text, or json to the log at specified severity.
now	Returns Unix time, as a floating-point number.
sleep	Suspends execution for the given number of seconds.
sleep_until	Suspends execution until the given time.

Module: text

Text processing.

To concatenate a string, see Strings.

Functions
decode	Decodes given data to string, assuming the specified character set.
encode	Encodes given text to bytes, using the specified character set.
find_all	Finds the index of all instances of a substring in a string.
find_all_regex	Finds all matches of a regular expression in a string.
match_regex	Reports whether a string contains a match of a regular expression.
replace_all	Replaces all instances of a substring with a new string.
replace_all_regex	Replaces all matches of a regular expression with a new string.
split	Splits the source string into a list of all substrings between each instance of the separator.
substring	Extracts the substring between two zero-based indexes of a source string.
to_lower	Returns a string with all Unicode letters mapped to their lowercase.
to_upper	Returns a string with all Unicode letters mapped to their uppercase.
url_decode	Returns a string with pluses and percent-escaped characters converted to UTF-8.
url_encode	Returns a string with percent-encoded reserved characters, including spaces.
url_encode_plus	Returns a string with percent-encoded reserved characters, and spaces replaced by pluses (+).

Module: time

Time-related utility functions.

Functions
format	Formats the given timestamp as a human-readable string.
parse	Parses the given RFC 3339-compatible string into a timestamp.

Module: uuid

UUID utility.

Functions
generate	Returns a random universally unique identifier (UUID).