Add schema to apt configure config (#357)

Create a schema object for the `apt_configure` module and
validate this schema in the `handle`  function of the module.

There are some considerations regarding this PR:

* The `primary` and `security` keys have the exact same properties. I
  tried to eliminate this redundancy by moving their properties to a
  common place and then just referencing it for both security and
  primary. Similar to what is documented here:
    https://json-schema.org/understanding-json-schema/structuring.html
  under the `Reuse` paragraph.  However, this approach does not work,
  because the `#` pointer goes to the beginning of the file, which is
  a python module instead of a json file, not allowing the pointer to
  find the correct definition. What I did was to create a separate dict
  for the mirror config and reuse it for primary and security, but
  maybe there are better approaches to do that.
* There was no documentation for the config `debconf_selections`. I
  tried to infer what it supposed to do by looking at the code and the
  `debconf-set-selections`  manpage, but my description may not be
  accurate or complete.
* Add a _parse_description function to schema.py to render multi-line
  preformatted content instead of squashing all whitespace

LP: #1858884

4 files changed, 396 insertions, 230 deletions

diff --git a/cloudinit/config/cc_apt_configure.py b/cloudinit/config/cc_apt_configure.py
index ff58c062..9a33451d 100644
--- a/cloudinit/config/cc_apt_configure.py
+++ b/cloudinit/config/cc_apt_configure.py
@@ -6,228 +6,371 @@
 #
 # This file is part of cloud-init. See LICENSE file for license information.
 
-"""
-Apt Configure
--------------
-**Summary:** configure apt
-
-This module handles both configuration of apt options and adding source lists.
-There are configuration options such as ``apt_get_wrapper`` and
-``apt_get_command`` that control how cloud-init invokes apt-get.
-These configuration options are handled on a per-distro basis, so consult
-documentation for cloud-init's distro support for instructions on using
-these config options.
-
-.. note::
-    To ensure that apt configuration is valid yaml, any strings containing
-    special characters, especially ``:`` should be quoted.
-
-.. note::
-    For more information about apt configuration, see the
-    ``Additional apt configuration`` example.
-
-**Preserve sources.list:**
-
-By default, cloud-init will generate a new sources list in
-``/etc/apt/sources.list.d`` based on any changes specified in cloud config.
-To disable this behavior and preserve the sources list from the pristine image,
-set ``preserve_sources_list`` to ``true``.
-
-.. note::
-    The ``preserve_sources_list`` option overrides all other config keys that
-    would alter ``sources.list`` or ``sources.list.d``, **except** for
-    additional sources to be added to ``sources.list.d``.
-
-**Disable source suites:**
-
-Entries in the sources list can be disabled using ``disable_suites``, which
-takes a list of suites to be disabled. If the string ``$RELEASE`` is present in
-a suite in the ``disable_suites`` list, it will be replaced with the release
-name. If a suite specified in ``disable_suites`` is not present in
-``sources.list`` it will be ignored. For convenience, several aliases are
-provided for ``disable_suites``:
-
-    - ``updates`` => ``$RELEASE-updates``
-    - ``backports`` => ``$RELEASE-backports``
-    - ``security`` => ``$RELEASE-security``
-    - ``proposed`` => ``$RELEASE-proposed``
-    - ``release`` => ``$RELEASE``
-
-.. note::
-    When a suite is disabled using ``disable_suites``, its entry in
-    ``sources.list`` is not deleted; it is just commented out.
-
-**Configure primary and security mirrors:**
-
-The primary and security archive mirrors can be specified using the ``primary``
-and ``security`` keys, respectively. Both the ``primary`` and ``security`` keys
-take a list of configs, allowing mirrors to be specified on a per-architecture
-basis. Each config is a dictionary which must have an entry for ``arches``,
-specifying which architectures that config entry is for. The keyword
-``default`` applies to any architecture not explicitly listed. The mirror url
-can be specified with the ``uri`` key, or a list of mirrors to check can be
-provided in order, with the first mirror that can be resolved being selected.
-This allows the same configuration to be used in different environment, with
-different hosts used for a local apt mirror. If no mirror is provided by
-``uri`` or ``search``, ``search_dns`` may be used to search for dns names in
-the format ``<distro>-mirror`` in each of the following:
-
-    - fqdn of this host per cloud metadata
-    - localdomain
-    - domains listed in ``/etc/resolv.conf``
-
-If there is a dns entry for ``<distro>-mirror``, then it is assumed that there
-is a distro mirror at ``http://<distro>-mirror.<domain>/<distro>``. If the
-``primary`` key is defined, but not the ``security`` key, then then
-configuration for ``primary`` is also used for ``security``. If ``search_dns``
-is used for the ``security`` key, the search pattern will be.
-``<distro>-security-mirror``.
-
-If no mirrors are specified, or all lookups fail, then default mirrors defined
-in the datasource are used. If none are present in the datasource either the
-following defaults are used:
-
-    - primary: ``http://archive.ubuntu.com/ubuntu``
-    - security: ``http://security.ubuntu.com/ubuntu``
-
-**Specify sources.list template:**
-
-A custom template for rendering ``sources.list`` can be specefied with
-``sources_list``. If no ``sources_list`` template is given, cloud-init will
-use sane default. Within this template, the following strings will be replaced
-with the appropriate values:
-
-    - ``$MIRROR``
-    - ``$RELEASE``
-    - ``$PRIMARY``
-    - ``$SECURITY``
-
-**Pass configuration to apt:**
-
-Apt configuration can be specified using ``conf``. Configuration is specified
-as a string. For multiline apt configuration, make sure to follow yaml syntax.
-
-**Configure apt proxy:**
-
-Proxy configuration for apt can be specified using ``conf``, but proxy config
-keys also exist for convenience. The proxy config keys, ``http_proxy``,
-``ftp_proxy``, and ``https_proxy`` may be used to specify a proxy for http, ftp
-and https protocols respectively. The ``proxy`` key also exists as an alias for
-``http_proxy``. Proxy url is specified in the format
-``<protocol>://[[user][:pass]@]host[:port]/``.
-
-**Add apt repos by regex:**
+"""Apt Configure: Configure apt for the user."""
 
-All source entries in ``apt-sources`` that match regex in
-``add_apt_repo_match`` will be added to the system using
-``add-apt-repository``. If ``add_apt_repo_match`` is not specified, it defaults
-to ``^[\\w-]+:\\w``
-
-**Add source list entries:**
-
-Source list entries can be specified as a dictionary under the ``sources``
-config key, with key in the dict representing a different source file. The key
-of each source entry will be used as an id that can be referenced in
-other config entries, as well as the filename for the source's configuration
-under ``/etc/apt/sources.list.d``. If the name does not end with ``.list``,
-it will be appended. If there is no configuration for a key in ``sources``, no
-file will be written, but the key may still be referred to as an id in other
-``sources`` entries.
-
-Each entry under ``sources`` is a dictionary which may contain any of the
-following optional keys:
-
-    - ``source``: a sources.list entry (some variable replacements apply)
-    - ``keyid``: a key to import via shortid or fingerprint
-    - ``key``: a raw PGP key
-    - ``keyserver``: alternate keyserver to pull ``keyid`` key from
-
-The ``source`` key supports variable replacements for the following strings:
-
-    - ``$MIRROR``
-    - ``$PRIMARY``
-    - ``$SECURITY``
-    - ``$RELEASE``
-
-**Internal name:** ``cc_apt_configure``
+import glob
+import os
+import re
+from textwrap import dedent
 
-**Module frequency:** per instance
+from cloudinit.config.schema import (
+    get_schema_doc, validate_cloudconfig_schema)
+from cloudinit import gpg
+from cloudinit import log as logging
+from cloudinit import templater
+from cloudinit import util
+from cloudinit.settings import PER_INSTANCE
 
-**Supported distros:** ubuntu, debian
+LOG = logging.getLogger(__name__)
 
-**Config keys**::
+# this will match 'XXX:YYY' (ie, 'cloud-archive:foo' or 'ppa:bar')
+ADD_APT_REPO_MATCH = r"^[\w-]+:\w"
 
-    apt:
-        preserve_sources_list: <true/false>
-        disable_suites:
+frequency = PER_INSTANCE
+distros = ["ubuntu", "debian"]
+mirror_property = {
+    'type': 'array',
+    'item': {
+        'type': 'object',
+        'additionalProperties': False,
+        'required': ['arches'],
+        'properties': {
+            'arches': {
+                'type': 'array',
+                'item': {
+                    'type': 'string'
+                },
+                'minItems': 1
+            },
+            'uri': {
+                'type': 'string',
+                'format': 'uri'
+            },
+            'search': {
+                'type': 'array',
+                'item': {
+                    'type': 'string',
+                    'format': 'uri'
+                },
+                'minItems': 1
+            },
+            'search_dns': {
+                'type': 'boolean',
+            }
+        }
+    }
+}
+schema = {
+    'id': 'cc_apt_configure',
+    'name': 'Apt Configure',
+    'title': 'Configure apt for the user',
+    'description': dedent("""\
+        This module handles both configuration of apt options and adding
+        source lists.  There are configuration options such as
+        ``apt_get_wrapper`` and ``apt_get_command`` that control how
+        cloud-init invokes apt-get. These configuration options are
+        handled on a per-distro basis, so consult documentation for
+        cloud-init's distro support for instructions on using
+        these config options.
+
+        .. note::
+            To ensure that apt configuration is valid yaml, any strings
+            containing special characters, especially ``:`` should be quoted.
+
+        .. note::
+            For more information about apt configuration, see the
+            ``Additional apt configuration`` example."""),
+    'distros': distros,
+    'examples': [dedent("""\
+        apt:
+          preserve_sources_list: false
+          disable_suites:
             - $RELEASE-updates
             - backports
             - $RELEASE
             - mysuite
-        primary:
+          primary:
             - arches:
                 - amd64
                 - i386
                 - default
-              uri: "http://us.archive.ubuntu.com/ubuntu"
+              uri: 'http://us.archive.ubuntu.com/ubuntu'
               search:
-                - "http://cool.but-sometimes-unreachable.com/ubuntu"
-                - "http://us.archive.ubuntu.com/ubuntu"
+                - 'http://cool.but-sometimes-unreachable.com/ubuntu'
+                - 'http://us.archive.ubuntu.com/ubuntu'
               search_dns: <true/false>
             - arches:
                 - s390x
                 - arm64
-              uri: "http://archive-to-use-for-arm64.example.com/ubuntu"
-        security:
+              uri: 'http://archive-to-use-for-arm64.example.com/ubuntu'
+          security:
             - arches:
                 - default
               search_dns: true
-        sources_list: |
-            deb $MIRROR $RELEASE main restricted
-            deb-src $MIRROR $RELEASE main restricted
-            deb $PRIMARY $RELEASE universe restricted
-            deb $SECURITY $RELEASE-security multiverse
-        debconf_selections:
-            set1: the-package the-package/some-flag boolean true
-        conf: |
-            APT {
-                Get {
-                    Assume-Yes "true";
-                    Fix-Broken "true";
+          sources_list: |
+              deb $MIRROR $RELEASE main restricted
+              deb-src $MIRROR $RELEASE main restricted
+              deb $PRIMARY $RELEASE universe restricted
+              deb $SECURITY $RELEASE-security multiverse
+          debconf_selections:
+              set1: the-package the-package/some-flag boolean true
+          conf: |
+              APT {
+                  Get {
+                      Assume-Yes 'true';
+                      Fix-Broken 'true';
+                  }
+              }
+          proxy: 'http://[[user][:pass]@]host[:port]/'
+          http_proxy: 'http://[[user][:pass]@]host[:port]/'
+          ftp_proxy: 'ftp://[[user][:pass]@]host[:port]/'
+          https_proxy: 'https://[[user][:pass]@]host[:port]/'
+          sources:
+              source1:
+                  keyid: 'keyid'
+                  keyserver: 'keyserverurl'
+                  source: 'deb http://<url>/ xenial main'
+              source2:
+                  source: 'ppa:<ppa-name>'
+              source3:
+                  source: 'deb $MIRROR $RELEASE multiverse'
+                  key: |
+                      ------BEGIN PGP PUBLIC KEY BLOCK-------
+                      <key data>
+                      ------END PGP PUBLIC KEY BLOCK-------""")],
+    'frequency': frequency,
+    'type': 'object',
+    'properties': {
+        'apt': {
+            'type': 'object',
+            'additionalProperties': False,
+            'properties': {
+                'preserve_sources_list': {
+                    'type': 'boolean',
+                    'default': False,
+                    'description': dedent("""\
+                        By default, cloud-init will generate a new sources
+                        list in ``/etc/apt/sources.list.d`` based on any
+                        changes specified in cloud config. To disable this
+                        behavior and preserve the sources list from the
+                        pristine image, set ``preserve_sources_list``
+                        to ``true``.
+
+                        The ``preserve_sources_list`` option overrides
+                        all other config keys that would alter
+                        ``sources.list`` or ``sources.list.d``,
+                        **except** for additional sources to be added
+                        to ``sources.list.d``.""")
+                },
+                'disable_suites': {
+                    'type': 'array',
+                    'items': {
+                        'type': 'string'
+                    },
+                    'uniqueItems': True,
+                    'description': dedent("""\
+                        Entries in the sources list can be disabled using
+                        ``disable_suites``, which takes a list of suites
+                        to be disabled. If the string ``$RELEASE`` is
+                        present in a suite in the ``disable_suites`` list,
+                        it will be replaced with the release name. If a
+                        suite specified in ``disable_suites`` is not
+                        present in ``sources.list`` it will be ignored.
+                        For convenience, several aliases are provided for
+                        ``disable_suites``:
+
+                            - ``updates`` => ``$RELEASE-updates``
+                            - ``backports`` => ``$RELEASE-backports``
+                            - ``security`` => ``$RELEASE-security``
+                            - ``proposed`` => ``$RELEASE-proposed``
+                            - ``release`` => ``$RELEASE``.
+
+                        When a suite is disabled using ``disable_suites``,
+                        its entry in ``sources.list`` is not deleted; it
+                        is just commented out.""")
+                },
+                'primary': {
+                    **mirror_property,
+                    'description': dedent("""\
+                        The primary and security archive mirrors can
+                        be specified using the ``primary`` and
+                        ``security`` keys, respectively. Both the
+                        ``primary`` and ``security`` keys take a list
+                        of configs, allowing mirrors to be specified
+                        on a per-architecture basis. Each config is a
+                        dictionary which must have an entry for
+                        ``arches``, specifying which architectures
+                        that config entry is for. The keyword
+                        ``default`` applies to any architecture not
+                        explicitly listed. The mirror url can be specified
+                        with the ``uri`` key, or a list of mirrors to
+                        check can be provided in order, with the first
+                        mirror that can be resolved being selected. This
+                        allows the same configuration to be used in
+                        different environment, with different hosts used
+                        for a local apt mirror. If no mirror is provided
+                        by ``uri`` or ``search``, ``search_dns`` may be
+                        used to search for dns names in the format
+                        ``<distro>-mirror`` in each of the following:
+
+                            - fqdn of this host per cloud metadata,
+                            - localdomain,
+                            - domains listed in ``/etc/resolv.conf``.
+
+                        If there is a dns entry for ``<distro>-mirror``,
+                        then it is assumed that there is a distro mirror
+                        at ``http://<distro>-mirror.<domain>/<distro>``.
+                        If the ``primary`` key is defined, but not the
+                        ``security`` key, then then configuration for
+                        ``primary`` is also used for ``security``.
+                        If ``search_dns`` is used for the ``security``
+                        key, the search pattern will be
+                        ``<distro>-security-mirror``.
+
+                        If no mirrors are specified, or all lookups fail,
+                        then default mirrors defined in the datasource
+                        are used. If none are present in the datasource
+                        either the following defaults are used:
+
+                            - ``primary`` => \
+                            ``http://archive.ubuntu.com/ubuntu``.
+                            - ``security`` => \
+                            ``http://security.ubuntu.com/ubuntu``
+                        """)},
+                'security': {
+                    **mirror_property,
+                    'description': dedent("""\
+                        Please refer to the primary config documentation""")
+                },
+                'add_apt_repo_match': {
+                    'type': 'string',
+                    'default': ADD_APT_REPO_MATCH,
+                    'description': dedent("""\
+                        All source entries in ``apt-sources`` that match
+                        regex in ``add_apt_repo_match`` will be added to
+                        the system using ``add-apt-repository``. If
+                        ``add_apt_repo_match`` is not specified, it
+                        defaults to ``{}``""".format(ADD_APT_REPO_MATCH))
+                },
+                'debconf_selections': {
+                    'type': 'object',
+                    'items': {'type': 'string'},
+                    'description': dedent("""\
+                        Debconf additional configurations can be specified as a
+                        dictionary under the ``debconf_selections`` config
+                        key, with each key in the dict representing a
+                        different set of configurations. The value of each key
+                        must be a string containing all the debconf
+                        configurations that must be applied. We will bundle
+                        all of the values and pass them to
+                        ``debconf-set-selections``. Therefore, each value line
+                        must be a valid entry for ``debconf-set-selections``,
+                        meaning that they must possess for distinct fields:
+
+                        ``pkgname question type answer``
+
+                        Where:
+
+                            - ``pkgname`` is the name of the package.
+                            - ``question`` the name of the questions.
+                            - ``type`` is the type of question.
+                            - ``answer`` is the value used to ansert the \
+                            question.
+
+                        For example: \
+                        ``ippackage ippackage/ip string 127.0.01``
+                    """)
+                },
+                'sources_list': {
+                    'type': 'string',
+                    'description': dedent("""\
+                       Specifies a custom template for rendering
+                       ``sources.list`` . If no ``sources_list`` template
+                       is given, cloud-init will use sane default. Within
+                       this template, the following strings will be
+                       replaced with the appropriate values:
+
+                            - ``$MIRROR``
+                            - ``$RELEASE``
+                            - ``$PRIMARY``
+                            - ``$SECURITY``""")
+                },
+                'conf': {
+                    'type': 'string',
+                    'description':  dedent("""\
+                        Specify configuration for apt, such as proxy
+                        configuration. This configuration is specified as a
+                        string. For multiline apt configuration, make sure
+                        to follow yaml syntax.""")
+                },
+                'https_proxy': {
+                    'type': 'string',
+                    'description': dedent("""\
+                        More convenient way to specify https apt proxy.
+                        https proxy url is specified in the format
+                        ``https://[[user][:pass]@]host[:port]/``.""")
+                },
+                'http_proxy': {
+                    'type': 'string',
+                    'description': dedent("""\
+                        More convenient way to specify http apt proxy.
+                        http proxy url is specified in the format
+                        ``http://[[user][:pass]@]host[:port]/``.""")
+                },
+                'proxy': {
+                    'type': 'string',
+                    'description': 'Alias for defining a http apt proxy.'
+                },
+                'ftp_proxy': {
+                    'type': 'string',
+                    'description': dedent("""\
+                        More convenient way to specify ftp apt proxy.
+                        ftp proxy url is specified in the format
+                        ``ftp://[[user][:pass]@]host[:port]/``.""")
+                },
+                'sources': {
+                    'type': 'object',
+                    'items': {'type': 'string'},
+                    'description': dedent("""\
+                        Source list entries can be specified as a
+                        dictionary under the ``sources`` config key, with
+                        each key in the dict representing a different source
+                        file. The key of each source entry will be used
+                        as an id that can be referenced in other config
+                        entries, as well as the filename for the source's
+                        configuration under ``/etc/apt/sources.list.d``.
+                        If the name does not end with ``.list``, it will
+                        be appended. If there is no configuration for a
+                        key in ``sources``, no file will be written, but
+                        the key may still be referred to as an id in other
+                        ``sources`` entries.
+
+                        Each entry under ``sources`` is a dictionary which
+                        may contain any of the following optional keys:
+
+                            - ``source``: a sources.list entry \
+                                  (some variable replacements apply).
+                            - ``keyid``: a key to import via shortid or \
+                                  fingerprint.
+                            - ``key``: a raw PGP key.
+                            - ``keyserver``: alternate keyserver to pull \
+                                    ``keyid`` key from.
+
+                        The ``source`` key supports variable
+                        replacements for the following strings:
+
+                            - ``$MIRROR``
+                            - ``$PRIMARY``
+                            - ``$SECURITY``
+                            - ``$RELEASE``""")
                 }
             }
-        proxy: "http://[[user][:pass]@]host[:port]/"
-        http_proxy: "http://[[user][:pass]@]host[:port]/"
-        ftp_proxy: "ftp://[[user][:pass]@]host[:port]/"
-        https_proxy: "https://[[user][:pass]@]host[:port]/"
-        sources:
-            source1:
-                keyid: "keyid"
-                keyserver: "keyserverurl"
-                source: "deb http://<url>/ xenial main"
-            source2:
-                source: "ppa:<ppa-name>"
-            source3:
-                source: "deb $MIRROR $RELEASE multiverse"
-                key: |
-                    ------BEGIN PGP PUBLIC KEY BLOCK-------
-                    <key data>
-                    ------END PGP PUBLIC KEY BLOCK-------
-"""
-
-import glob
-import os
-import re
-
-from cloudinit import gpg
-from cloudinit import log as logging
-from cloudinit import templater
-from cloudinit import util
+        }
+    }
+}
 
-LOG = logging.getLogger(__name__)
+__doc__ = get_schema_doc(schema)
 
-# this will match 'XXX:YYY' (ie, 'cloud-archive:foo' or 'ppa:bar')
-ADD_APT_REPO_MATCH = r"^[\w-]+:\w"
 
 # place where apt stores cached repository data
 APT_LISTS = "/var/lib/apt/lists"
@@ -279,6 +422,7 @@ def handle(name, ocfg, cloud, log, _):
             "Expected dictionary for 'apt' config, found {config_type}".format(
                 config_type=type(cfg)))
 
+    validate_cloudconfig_schema(cfg, schema)
     apply_debconf_selections(cfg, target)
     apply_apt(cfg, cloud, target)
 
diff --git a/cloudinit/config/cc_ntp.py b/cloudinit/config/cc_ntp.py
index 5498bbaa..3b2c2020 100644
--- a/cloudinit/config/cc_ntp.py
+++ b/cloudinit/config/cc_ntp.py
@@ -169,8 +169,8 @@ schema = {
                     'uniqueItems': True,
                     'description': dedent("""\
                         List of ntp pools. If both pools and servers are
-                         empty, 4 default pool servers will be provided of
-                         the format ``{0-3}.{distro}.pool.ntp.org``.""")
+                        empty, 4 default pool servers will be provided of
+                        the format ``{0-3}.{distro}.pool.ntp.org``.""")
                 },
                 'servers': {
                     'type': 'array',
@@ -181,46 +181,46 @@ schema = {
                     'uniqueItems': True,
                     'description': dedent("""\
                         List of ntp servers. If both pools and servers are
-                         empty, 4 default pool servers will be provided with
-                         the format ``{0-3}.{distro}.pool.ntp.org``.""")
+                        empty, 4 default pool servers will be provided with
+                        the format ``{0-3}.{distro}.pool.ntp.org``.""")
                 },
                 'ntp_client': {
                     'type': 'string',
                     'default': 'auto',
                     'description': dedent("""\
                         Name of an NTP client to use to configure system NTP.
-                         When unprovided or 'auto' the default client preferred
-                         by the distribution will be used. The following
-                         built-in client names can be used to override existing
-                         configuration defaults: chrony, ntp, ntpdate,
-                         systemd-timesyncd."""),
+                        When unprovided or 'auto' the default client preferred
+                        by the distribution will be used. The following
+                        built-in client names can be used to override existing
+                        configuration defaults: chrony, ntp, ntpdate,
+                        systemd-timesyncd."""),
                 },
                 'enabled': {
                     'type': 'boolean',
                     'default': True,
                     'description': dedent("""\
                         Attempt to enable ntp clients if set to True.  If set
-                         to False, ntp client will not be configured or
-                         installed"""),
+                        to False, ntp client will not be configured or
+                        installed"""),
                 },
                 'config': {
                     'description': dedent("""\
                         Configuration settings or overrides for the
-                         ``ntp_client`` specified."""),
+                        ``ntp_client`` specified."""),
                     'type': ['object'],
                     'properties': {
                         'confpath': {
                             'type': 'string',
                             'description': dedent("""\
                                 The path to where the ``ntp_client``
-                                 configuration is written."""),
+                                configuration is written."""),
                         },
                         'check_exe': {
                             'type': 'string',
                             'description': dedent("""\
                                 The executable name for the ``ntp_client``.
-                                 For example, ntp service ``check_exe`` is
-                                 'ntpd' because it runs the ntpd binary."""),
+                                For example, ntp service ``check_exe`` is
+                                'ntpd' because it runs the ntpd binary."""),
                         },
                         'packages': {
                             'type': 'array',
@@ -230,22 +230,22 @@ schema = {
                             'uniqueItems': True,
                             'description': dedent("""\
                                 List of packages needed to be installed for the
-                                 selected ``ntp_client``."""),
+                                selected ``ntp_client``."""),
                         },
                         'service_name': {
                             'type': 'string',
                             'description': dedent("""\
                                 The systemd or sysvinit service name used to
-                                 start and stop the ``ntp_client``
-                                 service."""),
+                                start and stop the ``ntp_client``
+                                service."""),
                         },
                         'template': {
                             'type': 'string',
                             'description': dedent("""\
                                 Inline template allowing users to define their
-                                 own ``ntp_client`` configuration template.
-                                 The value must start with '## template:jinja'
-                                 to enable use of templating support.
+                                own ``ntp_client`` configuration template.
+                                The value must start with '## template:jinja'
+                                to enable use of templating support.
                                 """),
                         },
                     },
diff --git a/cloudinit/config/cc_write_files.py b/cloudinit/config/cc_write_files.py
index 204cbfd6..8601e707 100644
--- a/cloudinit/config/cc_write_files.py
+++ b/cloudinit/config/cc_write_files.py
@@ -103,7 +103,7 @@ schema = {
                         'type': 'string',
                         'description': dedent("""\
                             Path of the file to which ``content`` is decoded
-                             and written
+                            and written
                         """),
                     },
                     'content': {
@@ -111,9 +111,9 @@ schema = {
                         'default': '',
                         'description': dedent("""\
                             Optional content to write to the provided ``path``.
-                              When content is present and encoding is not '%s',
-                              decode the content prior to writing. Default:
-                              **''**
+                            When content is present and encoding is not '%s',
+                            decode the content prior to writing. Default:
+                            **''**
                         """ % UNKNOWN_ENC),
                     },
                     'owner': {
@@ -121,7 +121,7 @@ schema = {
                         'default': DEFAULT_OWNER,
                         'description': dedent("""\
                             Optional owner:group to chown on the file. Default:
-                             **{owner}**
+                            **{owner}**
                         """.format(owner=DEFAULT_OWNER)),
                     },
                     'permissions': {
@@ -129,8 +129,8 @@ schema = {
                         'default': oct(DEFAULT_PERMS).replace('o', ''),
                         'description': dedent("""\
                             Optional file permissions to set on ``path``
-                             represented as an octal string '0###'. Default:
-                             **'{perms}'**
+                            represented as an octal string '0###'. Default:
+                            **'{perms}'**
                         """.format(perms=oct(DEFAULT_PERMS).replace('o', ''))),
                     },
                     'encoding': {
@@ -139,16 +139,16 @@ schema = {
                         'enum': supported_encoding_types,
                         'description': dedent("""\
                             Optional encoding type of the content. Default is
-                             **text/plain** and no content decoding is
-                             performed. Supported encoding types are:
-                             %s.""" % ", ".join(supported_encoding_types)),
+                            **text/plain** and no content decoding is
+                            performed. Supported encoding types are:
+                            %s.""" % ", ".join(supported_encoding_types)),
                     },
                     'append': {
                         'type': 'boolean',
                         'default': False,
                         'description': dedent("""\
                             Whether to append ``content`` to existing file if
-                             ``path`` exists. Default: **false**.
+                            ``path`` exists. Default: **false**.
                         """),
                     },
                 },
diff --git a/cloudinit/config/schema.py b/cloudinit/config/schema.py
index a295d63d..da00060a 100644
--- a/cloudinit/config/schema.py
+++ b/cloudinit/config/schema.py
@@ -306,6 +306,28 @@ def _get_property_type(property_dict):
     return property_type
 
 
+def _parse_description(description, prefix):
+    """Parse description from the schema in a format that we can better
+    display in our docs. This parser does three things:
+
+    - Guarantee that a paragraph will be in a single line
+    - Guarantee that each new paragraph will be aligned with
+      the first paragraph
+    - Proper align lists of items
+
+    @param description: The original description in the schema.
+    @param prefix: The number of spaces used to align the current description
+    """
+    list_paragraph = prefix * 3
+    description = re.sub(r"(\S)\n(\S)", r"\1 \2", description)
+    description = re.sub(
+        r"\n\n", r"\n\n{}".format(prefix), description)
+    description = re.sub(
+        r"\n( +)-", r"\n{}-".format(list_paragraph), description)
+
+    return description
+
+
 def _get_property_doc(schema, prefix='    '):
     """Return restructured text describing the supported schema properties."""
     new_prefix = prefix + '    '
@@ -318,7 +340,7 @@ def _get_property_doc(schema, prefix='    '):
             prefix=prefix,
             prop_name=prop_key,
             type=_get_property_type(prop_config),
-            description=description.replace('\n', '')))
+            description=_parse_description(description, prefix)))
         items = prop_config.get('items')
         if items:
             if isinstance(items, list):