read_csv: new module to read CSV files (#49578)

* read_csv: new module to read CSV files

* Add a doc reference to the csvfile lookup plugin

* Enable the use of custom dialect options

* Improve error handling

* Fix PEP8

* Fix more PEP8

* Simplify custom dialect code

* Add integration tests

* Fixes for CI

* Fix for python 2.6

lib/ansible/modules/files/read_csv.py

@@ -0,0 +1,235 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# Copyright: (c) 2018, Dag Wieers (@dagwieers) <dag@wieers.com>
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+from __future__ import absolute_import, division, print_function
+__metaclass__ = type
+
+ANSIBLE_METADATA = {'metadata_version': '1.1',
+                    'status': ['preview'],
+                    'supported_by': 'community'}
+
+DOCUMENTATION = r'''
+---
+module: read_csv
+version_added: '2.8'
+short_description: Read a CSV file
+description:
+- Read a CSV file and return a list or a dictionary, containing one dictionary per row.
+author:
+- Dag Wieers (@dagwieers)
+options:
+  path:
+    description:
+    - The CSV filename to read data from.
+    type: str
+    required: yes
+    aliases: [ filename ]
+  key:
+    description:
+    - The column name used as a key for the resulting dictionary.
+    - If C(key) is unset, the module returns a list of dictionaries,
+      where each dictionary is a row in the CSV file.
+    type: str
+  dialect:
+    description:
+    - The CSV dialect to use when parsing the CSV file.
+    - Possible values include C(excel), C(excel-tab) or C(unix).
+    type: str
+    default: excel
+  fieldnames:
+    description:
+    - A list of field names for every column.
+    - This is needed if the CSV does not have a header.
+    type: list
+  unique:
+    description:
+    - Whether the C(key) used is expected to be unique.
+    type: bool
+    default: yes
+  delimiter:
+    description:
+    - A one-character string used to separate fields.
+    - When using this parameter, you change the default value used by C(dialect).
+    - The default value depends on the dialect used.
+    type: str
+  skipinitialspace:
+    description:
+    - Whether to ignore any whitespaces immediately following the delimiter.
+    - When using this parameter, you change the default value used by C(dialect).
+    - The default value depends on the dialect used.
+    type: bool
+  strict:
+    description:
+    - Whether to raise an exception on bad CSV input.
+    - When using this parameter, you change the default value used by C(dialect).
+    - The default value depends on the dialect used.
+    type: bool
+notes:
+- Ansible also ships with the C(csvfile) lookup plugin, which can be used to do selective lookups in CSV files from Jinja.
+'''
+
+EXAMPLES = r'''
+# Example CSV file with header
+#
+#   name,uid,gid
+#   dag,500,500
+#   jeroen,501,500
+
+# Read a CSV file and access user 'dag'
+- name: Read users from CSV file and return a dictionary
+  read_csv:
+    path: users.csv
+    key: name
+  register: users
+  delegate_to: localhost
+
+- debug:
+    msg: 'User {{ users.dict.dag.name }} has UID {{ users.dict.dag.uid }} and GID {{ users.dict.dag.gid }}'
+
+# Read a CSV file and access the first item
+- name: Read users from CSV file and return a list
+  read_csv:
+    path: users.csv
+  register: users
+  delegate_to: localhost
+
+- debug:
+    msg: 'User {{ users.list.1.name }} has UID {{ users.list.1.uid }} and GID {{ users.list.1.gid }}'
+
+# Example CSV file without header and semi-colon delimiter
+#
+#   dag;500;500
+#   jeroen;501;500
+
+# Read a CSV file without headers
+- name: Read users from CSV file and return a list
+  read_csv:
+    path: users.csv
+    fieldnames: name,uid,gid
+    delimiter: ';'
+  register: users
+  delegate_to: localhost
+'''
+
+RETURN = r'''
+dict:
+  description: The CSV content as a dictionary.
+  returned: success
+  type: dict
+  sample:
+    dag:
+      name: dag
+      uid: 500
+      gid: 500
+    jeroen:
+      name: jeroen
+      uid: 501
+      gid: 500
+list:
+  description: The CSV content as a list.
+  returned: success
+  type: list
+  sample:
+  - name: dag
+    uid: 500
+    gid: 500
+  - name: jeroen
+    uid: 501
+    gid: 500
+'''
+
+import csv
+
+from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils._text import to_text
+
+
+# Add Unix dialect from Python 3
+class unix_dialect(csv.Dialect):
+    """Describe the usual properties of Unix-generated CSV files."""
+    delimiter = ','
+    quotechar = '"'
+    doublequote = True
+    skipinitialspace = False
+    lineterminator = '\n'
+    quoting = csv.QUOTE_ALL
+
+
+csv.register_dialect("unix", unix_dialect)
+
+
+def main():
+    module = AnsibleModule(
+        argument_spec=dict(
+            path=dict(type='path', required=True, aliases=['filename']),
+            dialect=dict(type='str', default='excel'),
+            key=dict(type='str'),
+            fieldnames=dict(type='list'),
+            unique=dict(type='bool', default=True),
+            delimiter=dict(type='str'),
+            skipinitialspace=dict(type='bool'),
+            strict=dict(type='bool'),
+        ),
+        supports_check_mode=True,
+    )
+
+    path = module.params['path']
+    dialect = module.params['dialect']
+    key = module.params['key']
+    fieldnames = module.params['fieldnames']
+    unique = module.params['unique']
+
+    if dialect not in csv.list_dialects():
+        module.fail_json(msg="Dialect '%s' is not supported by your version of python." % dialect)
+
+    dialect_options = dict(
+        delimiter=module.params['delimiter'],
+        skipinitialspace=module.params['skipinitialspace'],
+        strict=module.params['strict'],
+    )
+
+    # Create a dictionary from only set options
+    dialect_params = dict((k, v) for k, v in dialect_options.items() if v is not None)
+    if dialect_params:
+        try:
+            csv.register_dialect('custom', dialect, **dialect_params)
+        except TypeError as e:
+            module.fail_json(msg="Unable to create custom dialect: %s" % to_text(e))
+        dialect = 'custom'
+
+    try:
+        f = open(path, 'r')
+    except (IOError, OSError) as e:
+        module.fail_json(msg="Unable to open file: %s" % to_text(e))
+
+    reader = csv.DictReader(f, fieldnames=fieldnames, dialect=dialect)
+
+    if key and key not in reader.fieldnames:
+        module.fail_json(msg="Key '%s' was not found in the CSV header fields: %s" % (key, ', '.join(reader.fieldnames)))
+
+    data_dict = dict()
+    data_list = list()
+
+    if key is None:
+        try:
+            for row in reader:
+                data_list.append(row)
+        except csv.Error as e:
+            module.fail_json(msg="Unable to process file: %s" % to_text(e))
+    else:
+        try:
+            for row in reader:
+                if unique and row[key] in data_dict:
+                    module.fail_json(msg="Key '%s' is not unique for value '%s'" % (key, row[key]))
+                data_dict[row[key]] = row
+        except csv.Error as e:
+            module.fail_json(msg="Unable to process file: %s" % to_text(e))
+
+    module.exit_json(dict=data_dict, list=data_list)
+
+
+if __name__ == '__main__':
+    main()