Ansible Reference: Module Utilities

This page documents utilities intended to be helpful when writing Ansible modules in Python.


To use this functionality, include from ansible.module_utils.basic import AnsibleModule in your module.

class ansible.module_utils.basic.AnsibleModule(argument_spec, bypass_checks=False, no_log=False, mutually_exclusive=None, required_together=None, required_one_of=None, add_file_common_args=False, supports_check_mode=False, required_if=None, required_by=None)

Common code for quickly building an ansible module in Python (although you can write modules with anything that can return JSON).

See Developing Ansible modules for a general introduction and Ansible module architecture for more detailed explanation.


for results that are files, supplement the info about the file in the return path with stats about the file path.

atomic_move(src, dest, unsafe_writes=False)

atomically move src to dest, copying attributes from dest, returns true on success it uses os.rename to ensure this as it is an atomic operation, rest of the function is to work around limitations, corner cases and ensure selinux context is saved if possible


make a date-marked backup of the specified file, return True or False on success or failure


Convert the argument to a boolean

digest_from_file(filename, algorithm)

Return hex digest of local file for a digest_method specified by name, or None if file is not present.


return from the module, without error

fail_json(msg, **kwargs)

return from the module, with an error message


Takes a path and returns it’s mount point


path – a string type with a filesystem path


the path to the mount point as a text type

get_bin_path(arg, required=False, opt_dirs=None)

Find system executable in PATH.

  • arg – The executable to find.
  • required – if executable is not found and required is True, fail_json
  • opt_dirs – optional list of directories to search in addition to PATH

if found return full path; otherwise return None


is the given path executable?


path – The path of the file to check.


  • Does not account for FSACLs.
  • Most times we really want to know “Can the current user execute this file”. This function does not tell us that, only if any execute bit is set.

Returns a tuple containing (True, selinux_context) if the given path is on a NFS or other ‘special’ fs mount point, otherwise the return will be (False, None).

load_file_common_arguments(params, path=None)

many modules deal with files, this encapsulates common options that the file module accepts such that it is directly available to all modules and they can share code.

Allows to overwrite the path/dest module argument by providing path.


Return MD5 hex digest of local file using digest_from_file().

Do not use this function unless you have no other choice for:
  1. Optional backwards compatibility
  2. Compatibility with a third party protocol

This function will not work on systems complying with FIPS-140-2.

Most uses of this function can use the module.sha1 function instead.

preserved_copy(src, dest)

Copy a file with preserved ownership, permissions and context

run_command(args, check_rc=False, close_fds=True, executable=None, data=None, binary_data=False, path_prefix=None, cwd=None, use_unsafe_shell=False, prompt_regex=None, environ_update=None, umask=None, encoding='utf-8', errors='surrogate_or_strict', expand_user_and_vars=True, pass_fds=None, before_communicate_callback=None, ignore_invalid_cwd=True)

Execute a command, returns rc, stdout, and stderr.


args – is the command to run * If args is a list, the command will be run with shell=False. * If args is a string and use_unsafe_shell=False it will split args to a list and run with shell=False * If args is a string and use_unsafe_shell=True it runs with shell=True.

Kw check_rc

Whether to call fail_json in case of non zero RC. Default False

Kw close_fds

See documentation for subprocess.Popen(). Default True

Kw executable

See documentation for subprocess.Popen(). Default None

Kw data

If given, information to write to the stdin of the command

Kw binary_data

If False, append a newline to the data. Default False

Kw path_prefix

If given, additional path to find the command in. This adds to the PATH environment variable so helper commands in the same directory can also be found

Kw cwd

If given, working directory to run the command inside

Kw use_unsafe_shell

See args parameter. Default False

Kw prompt_regex

Regex string (not a compiled regex) which can be used to detect prompts in the stdout which would otherwise cause the execution to hang (especially if no input data is specified)

Kw environ_update

dictionary to update os.environ with

Kw umask

Umask to be used when running the command. Default None

Kw encoding

Since we return native strings, on python3 we need to know the encoding to use to transform from bytes to text. If you want to always get bytes back, use encoding=None. The default is “utf-8”. This does not affect transformation of strings given as args.

Kw errors

Since we return native strings, on python3 we need to transform stdout and stderr from bytes to text. If the bytes are undecodable in the encoding specified, then use this error handler to deal with them. The default is surrogate_or_strict which means that the bytes will be decoded using the surrogateescape error handler if available (available on all python3 versions we support) otherwise a UnicodeError traceback will be raised. This does not affect transformations of strings given as args.

Kw expand_user_and_vars

When use_unsafe_shell=False this argument dictates whether ~ is expanded in paths and environment variables are expanded before running the command. When True a string such as $SHELL will be expanded regardless of escaping. When False and use_unsafe_shell=False no path or variable expansion will be done.

Kw pass_fds

When running on Python 3 this argument dictates which file descriptors should be passed to an underlying Popen constructor. On Python 2, this will set close_fds to False.

Kw before_communicate_callback

This function will be called after Popen object will be created but before communicating to the process. (Popen object will be passed to callback as a first argument)

Kw ignore_invalid_cwd

This flag indicates whether an invalid cwd (non-existent or not a directory) should be ignored or should raise an exception.


A 3-tuple of return code (integer), stdout (native string), and stderr (native string). On python2, stdout and stderr are both byte strings. On python3, stdout and stderr are text strings converted according to the encoding and errors parameters. If you want byte strings on python3, use encoding=None to turn decoding to text off.


Return SHA1 hex digest of local file using digest_from_file().


Return SHA-256 hex digest of local file using digest_from_file().


To use this functionality, include import ansible.module_utils.basic in your module.


Deprecated: Use ansible.module_utils.common._utils.get_all_subclasses instead


Deprecated Use platform.system() directly.


Name of the platform the module is running on in a native string

Returns a native string that labels the platform (“Linux”, “Solaris”, etc). Currently, this is the result of calling platform.system().

ansible.module_utils.basic.heuristic_log_sanitize(data, no_log_values=None)

Remove strings that look like passwords from log messages

ansible.module_utils.basic.load_platform_subclass(cls, *args, **kwargs)

Deprecated: Use ansible.module_utils.common.sys_info.get_platform_subclass instead

Argument Spec

Classes and functions for validating parameters against an argument spec.


class ansible.module_utils.common.arg_spec.ArgumentSpecValidator(argument_spec, mutually_exclusive=None, required_together=None, required_one_of=None, required_if=None, required_by=None)

Argument spec validation class

Creates a validator based on the argument_spec that can be used to validate a number of parameters using the validate() method.

  • argument_spec (dict[str, dict]) – Specification of valid parameters and their type. May include nested argument specs.
  • mutually_exclusive (list[str] or list[list[str]]) – List or list of lists of terms that should not be provided together.
  • required_together (list[list[str]]) – List of lists of terms that are required together.
  • required_one_of (list[list[str]]) – List of lists of terms, one of which in each list is required.
  • required_if (list) – List of lists of [parameter, value, [parameters]] where one of [parameters] is required if parameter == value.
  • required_by (dict[str, list[str]]) – Dictionary of parameter names that contain a list of parameters required by each key in the dictionary.
validate(parameters, *args, **kwargs)

Validate parameters against argument spec.

Error messages in the ValidationResult may contain no_log values and should be sanitized with sanitize_keys() before logging or displaying.


parameters (dict[str, dict]) – Parameters to validate against the argument spec


ValidationResult containing validated parameters.

Simple Example
argument_spec = {
    'name': {'type': 'str'},
    'age': {'type': 'int'},

parameters = {
    'name': 'bo',
    'age': '42',

validator = ArgumentSpecValidator(argument_spec)
result = validator.validate(parameters)

if result.error_messages:
    sys.exit("Validation failed: {0}".format(", ".join(result.error_messages))

valid_params = result.validated_parameters


class ansible.module_utils.common.arg_spec.ValidationResult(parameters)

Result of argument spec validation.

This is the object returned by ArgumentSpecValidator.validate() containing the validated parameters and any errors.


parameters (dict) – Terms to be validated and coerced to the correct type.


AnsibleValidationErrorMultiple containing all AnsibleValidationError objects if there were any failures during validation.

property validated_parameters

Validated and coerced parameters.

property unsupported_parameters

set of unsupported parameter names.

property error_messages

list of all error messages from each exception in errors.



dict of type names, such as 'str', and the default function used to check that type, check_type_str() in this case.

ansible.module_utils.common.parameters.env_fallback(*args, **kwargs)

Load value from environment variable

ansible.module_utils.common.parameters.remove_values(value, no_log_strings)

Remove strings in no_log_strings from value.

If value is a container type, then remove a lot more.

Use of deferred_removals exists, rather than a pure recursive solution, because of the potential to hit the maximum recursion depth when dealing with large amounts of data (see issue #24560).

ansible.module_utils.common.parameters.sanitize_keys(obj, no_log_strings, ignore_keys=frozenset({}))

Sanitize the keys in a container object by removing no_log values from key names.

This is a companion function to the remove_values() function. Similar to that function, we make use of deferred_removals to avoid hitting maximum recursion depth in cases of large data structures.

  • obj – The container object to sanitize. Non-container objects are returned unmodified.
  • no_log_strings – A set of string values we do not want logged.
  • ignore_keys – A set of string values of keys to not sanitize.

An object with sanitized keys.


Standalone functions for validating various parameter types.

ansible.module_utils.common.validation.check_missing_parameters(parameters, required_parameters=None)

This is for checking for required params when we can not check via argspec because we need more information than is simply given in the argspec.

Raises TypeError if any required parameters are missing

  • parameters – Dictionary of parameters
  • required_parameters – List of parameters to look for in the given parameters.

Empty list or raises TypeError if the check fails.

ansible.module_utils.common.validation.check_mutually_exclusive(terms, parameters, options_context=None)

Check mutually exclusive terms against argument parameters

Accepts a single list or list of lists that are groups of terms that should be mutually exclusive with one another

  • terms – List of mutually exclusive parameters
  • parameters – Dictionary of parameters

Empty list or raises TypeError if the check fails.

ansible.module_utils.common.validation.check_required_arguments(argument_spec, parameters, options_context=None)

Check all parameters in argument_spec and return a list of parameters that are required but not present in parameters.

Raises TypeError if the check fails

  • argument_spec – Argument spec dictionary containing all parameters and their specification
  • parameters – Dictionary of parameters

Empty list or raises TypeError if the check fails.

ansible.module_utils.common.validation.check_required_by(requirements, parameters, options_context=None)

For each key in requirements, check the corresponding list to see if they exist in parameters.

Accepts a single string or list of values for each key.

  • requirements – Dictionary of requirements
  • parameters – Dictionary of parameters

Empty dictionary or raises TypeError if the

ansible.module_utils.common.validation.check_required_if(requirements, parameters, options_context=None)

Check parameters that are conditionally required

Raises TypeError if the check fails


requirements – List of lists specifying a parameter, value, parameters required when the given parameter is the specified value, and optionally a boolean indicating any or all parameters are required.

    ['state', 'present', ('path',), True],
    ['someint', 99, ('bool_param', 'string_param')],

parameters – Dictionary of parameters


Empty list or raises TypeError if the check fails. The results attribute of the exception contains a list of dictionaries. Each dictionary is the result of evaluating each item in requirements. Each return dictionary contains the following keys:

key missing

List of parameters that are required but missing

key requires

’any’ or ‘all’

key parameter

Parameter name that has the requirement

key value

Original value of the parameter

key requirements

Original required parameters

        'parameter': 'someint',
        'value': 99
        'requirements': ('bool_param', 'string_param'),
        'missing': ['string_param'],
        'requires': 'all',
ansible.module_utils.common.validation.check_required_one_of(terms, parameters, options_context=None)

Check each list of terms to ensure at least one exists in the given module parameters

Accepts a list of lists or tuples

  • terms – List of lists of terms to check. For each list of terms, at least one is required.
  • parameters – Dictionary of parameters
  • options_context – List of strings of parent key names if terms are in a sub spec.

Empty list or raises TypeError if the check fails.

ansible.module_utils.common.validation.check_required_together(terms, parameters, options_context=None)

Check each list of terms to ensure every parameter in each list exists in the given parameters.

Accepts a list of lists or tuples.

  • terms – List of lists of terms to check. Each list should include parameters that are all required when at least one is specified in the parameters.
  • parameters – Dictionary of parameters

Empty list or raises TypeError if the check fails.


Convert a human-readable string bits value to bits in integer.

Example: check_type_bits('1Mb') returns integer 1048576.

Raises TypeError if unable to covert the value.


Verify that the value is a bool or convert it to a bool and return it.

Raises TypeError if unable to convert to a bool


value – String, int, or float to convert to bool. Valid booleans include: ‘1’, ‘on’, 1, ‘0’, 0, ‘n’, ‘f’, ‘false’, ‘true’, ‘y’, ‘t’, ‘yes’, ‘no’, ‘off’


Boolean True or False


Convert a human-readable string value to bytes

Raises TypeError if unable to covert the value


Verify that value is a dict or convert it to a dict and return it.

Raises TypeError if unable to convert to a dict


value – Dict or string to convert to a dict. Accepts k1=v2, k2=v2.


value converted to a dictionary


Verify that value is a float or convert it to a float and return it

Raises TypeError if unable to convert to a float


value – float, int, str, or bytes to verify or convert and return.


float of given value.


Verify that the value is an integer and return it or convert the value to an integer and return it

Raises TypeError if unable to convert to an int


value – String or int to convert of verify


int of given value


Return a jsonified string. Sometimes the controller turns a json string into a dict/list so transform it back into json here

Raises TypeError if unable to covert the value


Verify that the value is a list or convert to a list

A comma separated string will be split into a list. Raises a TypeError if unable to convert to a list.


value – Value to validate or convert to a list


Original value if it is already a list, single item list if a float, int, or string without commas, or a multi-item list if a comma-delimited string.


Verify the provided value is a string or convert it to a string, then return the expanded path


Returns the raw value

ansible.module_utils.common.validation.check_type_str(value, allow_conversion=True, param=None, prefix='')

Verify that the value is a string or convert to a string.

Since unexpected changes can sometimes happen when converting to a string, allow_conversion controls whether or not the value will be converted or a TypeError will be raised if the value is not a string and would be converted

  • value – Value to validate or convert to a string
  • allow_conversion – Whether to convert the string and return it or raise a TypeError

Original value if it is a string, the value converted to a string if allow_conversion=True, or raises a TypeError if allow_conversion=False.

ansible.module_utils.common.validation.count_terms(terms, parameters)

Count the number of occurrences of a key in a given dictionary

  • terms – String or iterable of values to check
  • parameters – Dictionary of parameters

An integer that is the number of occurrences of the terms values in the provided dictionary.


exception ansible.module_utils.errors.AnsibleFallbackNotFound

Fallback validator was not found

exception ansible.module_utils.errors.AnsibleValidationError(message)

Single argument spec validation error


The error message passed in when the exception was raised.

property msg

The error message passed in when the exception was raised.

exception ansible.module_utils.errors.AnsibleValidationErrorMultiple(errors=None)

Multiple argument spec validation errors


list of AnsibleValidationError objects

property msg

The first message from the first error in errors.

property messages

list of each error message in errors.


Append a new error to self.errors.

Only AnsibleValidationError should be added.


Append each item in errors to self.errors. Only AnsibleValidationError should be added.

exception ansible.module_utils.errors.AliasError(message)

Error handling aliases

exception ansible.module_utils.errors.ArgumentTypeError(message)

Error with parameter type

exception ansible.module_utils.errors.ArgumentValueError(message)

Error with parameter value

exception ansible.module_utils.errors.ElementError(message)

Error when validating elements

exception ansible.module_utils.errors.MutuallyExclusiveError(message)

Mutually exclusive parameters were supplied

exception ansible.module_utils.errors.NoLogError(message)

Error converting no_log values

exception ansible.module_utils.errors.RequiredByError(message)

Error with parameters that are required by other parameters

exception ansible.module_utils.errors.RequiredDefaultError(message)

A required parameter was assigned a default value

exception ansible.module_utils.errors.RequiredError(message)

Missing a required parameter

exception ansible.module_utils.errors.RequiredIfError(message)

Error with conditionally required parameters

exception ansible.module_utils.errors.RequiredOneOfError(message)

Error with parameters where at least one is required

exception ansible.module_utils.errors.RequiredTogetherError(message)

Error with parameters that are required together

exception ansible.module_utils.errors.SubParameterTypeError(message)

Incorrect type for subparameter

exception ansible.module_utils.errors.UnsupportedError(message)

Unsupported parameters were supplied

© 2012–2018 Michael DeHaan
© 2018–2021 Red Hat, Inc.
Licensed under the GNU General Public License version 3.