schema and docs: Add jsonschema to resizefs and bootcmd modules

Add schema definitions to both cc_resizefs and cc_bootcmd modules. Extend
schema.py to parse and document enumerated json types. Schema definitions
are used to generate module documention and log warnings for schema
infractions.

This branch also does the following:
  - drops vestigial 'resize_rootfs_tmp' option from cc_resizefs. That
    option only created the specified directory and didn't make use of
that directory for any resize operations.
  - Drop yaml.dumps calls from schema documentation generation to avoid
    yaml import costs on module load
  - Add __doc__ = get_schema_doc(schema) definitions it each module to
    supplement python help() calls for cc_runcmd, cc_bootcmd, cc_ntp and
    cc_resizefs
  - Add a SCHEMA_EXAMPLES_SPACER_TEMPLATE string to docs for modules which
    contain more than one example

1 files changed, 85 insertions, 64 deletions

diff --git a/cloudinit/config/cc_resizefs.py b/cloudinit/config/cc_resizefs.py
index ceee952b..f14d3836 100644
--- a/cloudinit/config/cc_resizefs.py
+++ b/cloudinit/config/cc_resizefs.py
@@ -6,31 +6,8 @@
 #
 # This file is part of cloud-init. See LICENSE file for license information.
 
-"""
-Resizefs
---------
-**Summary:** resize filesystem
+"""Resizefs: cloud-config module which resizes the filesystem"""
 
-Resize a filesystem to use all avaliable space on partition. This module is
-useful along with ``cc_growpart`` and will ensure that if the root partition
-has been resized the root filesystem will be resized along with it. By default,
-``cc_resizefs`` will resize the root partition and will block the boot process
-while the resize command is running. Optionally, the resize operation can be
-performed in the background while cloud-init continues running modules. This
-can be enabled by setting ``resize_rootfs`` to ``true``. This module can be
-disabled altogether by setting ``resize_rootfs`` to ``false``.
-
-**Internal name:** ``cc_resizefs``
-
-**Module frequency:** per always
-
-**Supported distros:** all
-
-**Config keys**::
-
-    resize_rootfs: <true/false/"noblock">
-    resize_rootfs_tmp: <directory>
-"""
 
 import errno
 import getopt
@@ -38,11 +15,47 @@ import os
 import re
 import shlex
 import stat
+from textwrap import dedent
 
+from cloudinit.config.schema import (
+    get_schema_doc, validate_cloudconfig_schema)
 from cloudinit.settings import PER_ALWAYS
 from cloudinit import util
 
+NOBLOCK = "noblock"
+
 frequency = PER_ALWAYS
+distros = ['all']
+
+schema = {
+    'id': 'cc_resizefs',
+    'name': 'Resizefs',
+    'title': 'Resize filesystem',
+    'description': dedent("""\
+        Resize a filesystem to use all avaliable space on partition. This
+        module is useful along with ``cc_growpart`` and will ensure that if the
+        root partition has been resized the root filesystem will be resized
+        along with it. By default, ``cc_resizefs`` will resize the root
+        partition and will block the boot process while the resize command is
+        running. Optionally, the resize operation can be performed in the
+        background while cloud-init continues running modules. This can be
+        enabled by setting ``resize_rootfs`` to ``true``. This module can be
+        disabled altogether by setting ``resize_rootfs`` to ``false``."""),
+    'distros': distros,
+    'examples': [
+        'resize_rootfs: false  # disable root filesystem resize operation'],
+    'frequency': PER_ALWAYS,
+    'type': 'object',
+    'properties': {
+        'resize_rootfs': {
+            'enum': [True, False, NOBLOCK],
+            'description': dedent("""\
+                Whether to resize the root partition. Default: 'true'""")
+        }
+    }
+}
+
+__doc__ = get_schema_doc(schema)  # Supplement python help()
 
 
 def _resize_btrfs(mount_point, devpth):
@@ -131,8 +144,6 @@ RESIZE_FS_PRECHECK_CMDS = {
     'ufs': _can_skip_resize_ufs
 }
 
-NOBLOCK = "noblock"
-
 
 def rootdev_from_cmdline(cmdline):
     found = None
@@ -161,71 +172,81 @@ def can_skip_resize(fs_type, resize_what, devpth):
     return False
 
 
-def handle(name, cfg, _cloud, log, args):
-    if len(args) != 0:
-        resize_root = args[0]
-    else:
-        resize_root = util.get_cfg_option_str(cfg, "resize_rootfs", True)
-
-    if not util.translate_bool(resize_root, addons=[NOBLOCK]):
-        log.debug("Skipping module named %s, resizing disabled", name)
-        return
-
-    # TODO(harlowja) is the directory ok to be used??
-    resize_root_d = util.get_cfg_option_str(cfg, "resize_rootfs_tmp", "/run")
-    util.ensure_dir(resize_root_d)
+def is_device_path_writable_block(devpath, info, log):
+    """Return True if devpath is a writable block device.
 
-    # TODO(harlowja): allow what is to be resized to be configurable??
-    resize_what = "/"
-    result = util.get_mount_info(resize_what, log)
-    if not result:
-        log.warn("Could not determine filesystem type of %s", resize_what)
-        return
-
-    (devpth, fs_type, mount_point) = result
-
-    info = "dev=%s mnt_point=%s path=%s" % (devpth, mount_point, resize_what)
-    log.debug("resize_info: %s" % info)
+    @param devpath: Path to the root device we want to resize.
+    @param info: String representing information about the requested device.
+    @param log: Logger to which logs will be added upon error.
 
+    @returns Boolean True if block device is writable
+    """
     container = util.is_container()
 
     # Ensure the path is a block device.
-    if (devpth == "/dev/root" and not os.path.exists(devpth) and
+    if (devpath == "/dev/root" and not os.path.exists(devpath) and
             not container):
-        devpth = util.rootdev_from_cmdline(util.get_cmdline())
-        if devpth is None:
+        devpath = util.rootdev_from_cmdline(util.get_cmdline())
+        if devpath is None:
             log.warn("Unable to find device '/dev/root'")
-            return
-        log.debug("Converted /dev/root to '%s' per kernel cmdline", devpth)
+            return False
+        log.debug("Converted /dev/root to '%s' per kernel cmdline", devpath)
 
     try:
-        statret = os.stat(devpth)
+        statret = os.stat(devpath)
     except OSError as exc:
         if container and exc.errno == errno.ENOENT:
             log.debug("Device '%s' did not exist in container. "
-                      "cannot resize: %s", devpth, info)
+                      "cannot resize: %s", devpath, info)
         elif exc.errno == errno.ENOENT:
             log.warn("Device '%s' did not exist. cannot resize: %s",
-                     devpth, info)
+                     devpath, info)
         else:
             raise exc
-        return
+        return False
 
-    if not os.access(devpth, os.W_OK):
+    if not os.access(devpath, os.W_OK):
         if container:
             log.debug("'%s' not writable in container. cannot resize: %s",
-                      devpth, info)
+                      devpath, info)
         else:
-            log.warn("'%s' not writable. cannot resize: %s", devpth, info)
+            log.warn("'%s' not writable. cannot resize: %s", devpath, info)
         return
 
     if not stat.S_ISBLK(statret.st_mode) and not stat.S_ISCHR(statret.st_mode):
         if container:
             log.debug("device '%s' not a block device in container."
-                      " cannot resize: %s" % (devpth, info))
+                      " cannot resize: %s" % (devpath, info))
         else:
             log.warn("device '%s' not a block device. cannot resize: %s" %
-                     (devpth, info))
+                     (devpath, info))
+        return False
+    return True
+
+
+def handle(name, cfg, _cloud, log, args):
+    if len(args) != 0:
+        resize_root = args[0]
+    else:
+        resize_root = util.get_cfg_option_str(cfg, "resize_rootfs", True)
+    validate_cloudconfig_schema(cfg, schema)
+    if not util.translate_bool(resize_root, addons=[NOBLOCK]):
+        log.debug("Skipping module named %s, resizing disabled", name)
+        return
+
+    # TODO(harlowja): allow what is to be resized to be configurable??
+    resize_what = "/"
+    result = util.get_mount_info(resize_what, log)
+    if not result:
+        log.warn("Could not determine filesystem type of %s", resize_what)
+        return
+
+    (devpth, fs_type, mount_point) = result
+
+    info = "dev=%s mnt_point=%s path=%s" % (devpth, mount_point, resize_what)
+    log.debug("resize_info: %s" % info)
+
+    if not is_device_path_writable_block(devpth, info, log):
         return
 
     resizer = None