Single JSON schema validation in early boot (#1175)

Package a single JSON schema file for user-data validation at
cloudinit/config/cloud-init-schema.json.

Perform validate_cloudconfig_schema call to just after the
user-data is consumed. This will allow single validation of all
user-data against the full schema instead of
repetitive validatation calls against each cloud-config module
(cloudinit.config.cc_*) sub-schemas.

This branch defines the simple apt_pipelining schema and
migrates existing cc_apk_configure into cloud-init-schema.json.

The expectation will be additional branches to migrate from legacy
"schema" attributes inside each cloud-config module toward unique
cc_<module_name> definitions in the global shema file under "$defs"
of cloud-init-schema-X.Y..json.

Before legacy sub-schema definitions are migrated the following
funcs grew support to read sub-schemas from both static
cloud-init-schema.json and the individual cloud-config module
"schema" attributes:

- get_schema: source base schema file from cloud-init-schema.json
  and supplement with all legacy cloud-config module "schema" defs
- get_meta_doc: optional schema param so cloud-config modules
  no longer provide the own local sub-schemas
- _get_property_doc: render only documentation of sub-schema based
  on meta['id'] provided
- validate_cloudconfig_schema: allow optional schema param


Additionally, fix two minor bugs in _schemapath_for_cloudconfig:
- `cloud-init devel schema --annotate` which results in a Traceback
  if two keys at the same indent level have invalid types.
- exit early on empty cloud-config to avoid a Traceback on the CLI

4 files changed, 180 insertions, 154 deletions

diff --git a/cloudinit/config/cc_apk_configure.py b/cloudinit/config/cc_apk_configure.py
index a615c814..2cb2dad1 100644
--- a/cloudinit/config/cc_apk_configure.py
+++ b/cloudinit/config/cc_apk_configure.py
@@ -10,7 +10,7 @@ from textwrap import dedent
 
 from cloudinit import log as logging
 from cloudinit import temp_utils, templater, util
-from cloudinit.config.schema import get_meta_doc, validate_cloudconfig_schema
+from cloudinit.config.schema import get_meta_doc
 from cloudinit.settings import PER_INSTANCE
 
 LOG = logging.getLogger(__name__)
@@ -102,104 +102,7 @@ meta = {
     "frequency": frequency,
 }
 
-schema = {
-    "type": "object",
-    "properties": {
-        "apk_repos": {
-            "type": "object",
-            "properties": {
-                "preserve_repositories": {
-                    "type": "boolean",
-                    "default": False,
-                    "description": dedent(
-                        """\
-                        By default, cloud-init will generate a new repositories
-                        file ``/etc/apk/repositories`` based on any valid
-                        configuration settings specified within a apk_repos
-                        section of cloud config. To disable this behavior and
-                        preserve the repositories file from the pristine image,
-                        set ``preserve_repositories`` to ``true``.
-
-                        The ``preserve_repositories`` option overrides
-                        all other config keys that would alter
-                        ``/etc/apk/repositories``.
-                    """
-                    ),
-                },
-                "alpine_repo": {
-                    "type": ["object", "null"],
-                    "properties": {
-                        "base_url": {
-                            "type": "string",
-                            "default": DEFAULT_MIRROR,
-                            "description": dedent(
-                                """\
-                                The base URL of an Alpine repository, or
-                                mirror, to download official packages from.
-                                If not specified then it defaults to ``{}``
-                            """.format(
-                                    DEFAULT_MIRROR
-                                )
-                            ),
-                        },
-                        "community_enabled": {
-                            "type": "boolean",
-                            "default": False,
-                            "description": dedent(
-                                """\
-                                Whether to add the Community repo to the
-                                repositories file. By default the Community
-                                repo is not included.
-                            """
-                            ),
-                        },
-                        "testing_enabled": {
-                            "type": "boolean",
-                            "default": False,
-                            "description": dedent(
-                                """\
-                                Whether to add the Testing repo to the
-                                repositories file. By default the Testing
-                                repo is not included. It is only recommended
-                                to use the Testing repo on a machine running
-                                the ``Edge`` version of Alpine as packages
-                                installed from Testing may have dependancies
-                                that conflict with those in non-Edge Main or
-                                Community repos."
-                            """
-                            ),
-                        },
-                        "version": {
-                            "type": "string",
-                            "description": dedent(
-                                """\
-                                The Alpine version to use (e.g. ``v3.12`` or
-                                ``edge``)
-                            """
-                            ),
-                        },
-                    },
-                    "required": ["version"],
-                    "minProperties": 1,
-                    "additionalProperties": False,
-                },
-                "local_repo_base_url": {
-                    "type": "string",
-                    "description": dedent(
-                        """\
-                        The base URL of an Alpine repository containing
-                        unofficial packages
-                    """
-                    ),
-                },
-            },
-            "minProperties": 1,  # Either preserve_repositories or alpine_repo
-            "additionalProperties": False,
-        }
-    },
-}
-
-__doc__ = get_meta_doc(meta, schema)
+__doc__ = get_meta_doc(meta)
 
 
 def handle(name, cfg, cloud, log, _args):
@@ -222,8 +125,6 @@ def handle(name, cfg, cloud, log, _args):
         )
         return
 
-    validate_cloudconfig_schema(cfg, schema)
-
     # If "preserve_repositories" is explicitly set to True in
     # the configuration do nothing.
     if util.get_cfg_option_bool(apk_section, "preserve_repositories", False):
diff --git a/cloudinit/config/cc_apt_pipelining.py b/cloudinit/config/cc_apt_pipelining.py
index 569849d1..34b6ac0e 100644
--- a/cloudinit/config/cc_apt_pipelining.py
+++ b/cloudinit/config/cc_apt_pipelining.py
@@ -4,54 +4,59 @@
 #
 # This file is part of cloud-init. See LICENSE file for license information.
 
-"""
-Apt Pipelining
---------------
-**Summary:** configure apt pipelining
+"""Apt Pipelining: configure apt pipelining."""
 
-This module configures apt's ``Acquite::http::Pipeline-Depth`` option, which
-controls how apt handles HTTP pipelining. It may be useful for pipelining to be
-disabled, because some web servers, such as S3 do not pipeline properly (LP:
-#948461). The ``apt_pipelining`` config key may be set to ``false`` to disable
-pipelining altogether. This is the default behavior. If it is set to ``none``,
-``unchanged``, or ``os``, no change will be made to apt configuration and the
-default setting for the distro will be used. The pipeline depth can also be
-manually specified by setting ``apt_pipelining`` to a number. However, this is
-not recommended.
-
-**Internal name:** ``cc_apt_pipelining``
-
-**Module frequency:** per instance
-
-**Supported distros:** ubuntu, debian
-
-**Config keys**::
-    apt_pipelining: <false/none/unchanged/os/number>
-"""
+from textwrap import dedent
 
 from cloudinit import util
+from cloudinit.config.schema import get_meta_doc
 from cloudinit.settings import PER_INSTANCE
 
 frequency = PER_INSTANCE
-
 distros = ["ubuntu", "debian"]
-
 DEFAULT_FILE = "/etc/apt/apt.conf.d/90cloud-init-pipelining"
-
 APT_PIPE_TPL = (
     "//Written by cloud-init per 'apt_pipelining'\n"
     'Acquire::http::Pipeline-Depth "%s";\n'
 )
-
 # Acquire::http::Pipeline-Depth can be a value
 # from 0 to 5 indicating how many outstanding requests APT should send.
 # A value of zero MUST be specified if the remote host does not properly linger
 # on TCP connections - otherwise data corruption will occur.
 
+meta = {
+    "id": "cc_apt_pipelining",
+    "name": "Apt Pipelining",
+    "title": "Configure apt pipelining",
+    "description": dedent(
+        """\
+        This module configures apt's ``Acquite::http::Pipeline-Depth`` option,
+        which controls how apt handles HTTP pipelining. It may be useful for
+        pipelining to be disabled, because some web servers, such as S3 do not
+        pipeline properly (LP: #948461).
+
+        Value configuration options for this module are:
+
+        * ``false`` (Default): disable pipelining altogether
+        * ``none``, ``unchanged``, or ``os``: use distro default
+        * ``<number>``: Manually specify pipeline depth. This is not recommended."""  # noqa: E501
+    ),
+    "distros": distros,
+    "frequency": frequency,
+    "examples": [
+        "apt_pipelining: false",
+        "apt_pipelining: none",
+        "apt_pipelining: unchanged",
+        "apt_pipelining: os",
+        "apt_pipelining: 3",
+    ],
+}
+
+__doc__ = get_meta_doc(meta)
 
-def handle(_name, cfg, _cloud, log, _args):
 
-    apt_pipe_value = util.get_cfg_option_str(cfg, "apt_pipelining", "os")
+def handle(_name, cfg, _cloud, log, _args):
+    apt_pipe_value = cfg.get("apt_pipelining", "os")
     apt_pipe_value_s = str(apt_pipe_value).lower().strip()
 
     if apt_pipe_value_s == "false":
diff --git a/cloudinit/config/cloud-init-schema.json b/cloudinit/config/cloud-init-schema.json
new file mode 100644
index 00000000..afaed285
--- /dev/null
+++ b/cloudinit/config/cloud-init-schema.json
@@ -0,0 +1,69 @@
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "$defs": {
+    "cc_apk_configure": {
+      "type": "object",
+      "properties": {
+        "apk_repos": {
+          "type": "object",
+          "properties": {
+            "preserve_repositories": {
+              "type": "boolean",
+              "default": false,
+              "description": "By default, cloud-init will generate a new repositories file ``/etc/apk/repositories`` based on any valid configuration settings specified within a apk_repos section of cloud config. To disable this behavior and preserve the repositories file from the pristine image, set ``preserve_repositories`` to ``true``.\n\n The ``preserve_repositories`` option overrides all other config keys that would alter ``/etc/apk/repositories``."
+            },
+            "alpine_repo": {
+              "type": ["object", "null"],
+              "properties": {
+                "base_url": {
+                  "type": "string",
+                  "default": "https://alpine.global.ssl.fastly.net/alpine",
+                  "description": "The base URL of an Alpine repository, or mirror, to download official packages from. If not specified then it defaults to ``https://alpine.global.ssl.fastly.net/alpine``"
+                },
+                "community_enabled": {
+                  "type": "boolean",
+                  "default": false,
+                  "description": "Whether to add the Community repo to the repositories file. By default the Community repo is not included."
+                },
+                "testing_enabled": {
+                  "type": "boolean",
+                  "default": false,
+                  "description": "Whether to add the Testing repo to the repositories file. By default the Testing repo is not included. It is only recommended to use the Testing repo on a machine running the ``Edge`` version of Alpine as packages installed from Testing may have dependancies that conflict with those in non-Edge Main or Community repos."
+                },
+                "version": {
+                  "type": "string",
+                  "description": "The Alpine version to use (e.g. ``v3.12`` or ``edge``)"
+                }
+              },
+              "required": ["version"],
+              "minProperties": 1,
+              "additionalProperties": false
+            },
+            "local_repo_base_url": {
+              "type": "string",
+                "description": "The base URL of an Alpine repository containing unofficial packages"
+            }
+          },
+          "minProperties": 1,
+          "additionalProperties": false
+        }
+      }
+    },
+    "cc_apt_pipelining": {
+      "type": "object",
+      "properties": {
+        "apt_pipelining": {
+          "oneOf": [
+            {"type": "integer"},
+            {"type": "boolean"},
+            {"type": "string", "enum": ["none", "unchanged", "os"]}
+          ]
+        }
+      }
+    }
+  },
+  "allOf": [
+    { "$ref": "#/$defs/cc_apk_configure" },
+    { "$ref": "#/$defs/cc_apt_pipelining" }
+  ]
+}
diff --git a/cloudinit/config/schema.py b/cloudinit/config/schema.py
index f54cf18f..1f969c97 100644
--- a/cloudinit/config/schema.py
+++ b/cloudinit/config/schema.py
@@ -2,6 +2,7 @@
 """schema.py: Set of module functions for processing cloud-config schema."""
 
 import argparse
+import json
 import logging
 import os
 import re
@@ -166,14 +167,18 @@ def validate_cloudconfig_metaschema(validator, schema: dict, throw=True):
 
 
 def validate_cloudconfig_schema(
-    config: dict, schema: dict, strict=False, strict_metaschema=False
+    config: dict,
+    schema: dict = None,
+    strict: bool = False,
+    strict_metaschema: bool = False,
 ):
     """Validate provided config meets the schema definition.
 
     @param config: Dict of cloud configuration settings validated against
         schema. Ignored if strict_metaschema=True
     @param schema: jsonschema dict describing the supported schema definition
-       for the cloud config module (config.cc_*).
+       for the cloud config module (config.cc_*). If None, validate against
+       global schema.
     @param strict: Boolean, when True raise SchemaValidationErrors instead of
        logging warnings.
     @param strict_metaschema: Boolean, when True validates schema using strict
@@ -183,6 +188,8 @@ def validate_cloudconfig_schema(
         against the provided schema.
     @raises: RuntimeError when provided config sourced from YAML is not a dict.
     """
+    if schema is None:
+        schema = get_schema()
     try:
         (cloudinitValidator, FormatChecker) = get_jsonschema_validator()
         if strict_metaschema:
@@ -203,7 +210,9 @@ def validate_cloudconfig_schema(
             raise SchemaValidationError(errors)
         else:
             messages = ["{0}: {1}".format(k, msg) for k, msg in errors]
-            LOG.warning("Invalid config:\n%s", "\n".join(messages))
+            LOG.warning(
+                "Invalid cloud-config provided:\n%s", "\n".join(messages)
+            )
 
 
 def annotated_cloudconfig_file(cloudconfig, original_content, schema_errors):
@@ -347,12 +356,14 @@ def _schemapath_for_cloudconfig(config, original_content):
     @param config: The yaml.loaded config dictionary of a cloud-config file.
     @param original_content: The simple file content of the cloud-config file
     """
-    # FIXME Doesn't handle multi-line lists or multi-line strings
+    # TODO( handle multi-line lists or multi-line strings, inline dicts)
     content_lines = original_content.decode().split("\n")
     schema_line_numbers = {}
     list_index = 0
     RE_YAML_INDENT = r"^(\s*)"
     scopes = []
+    if not config:
+        return {}  # No YAML config dict, no schemapaths to annotate
     for line_number, line in enumerate(content_lines, 1):
         indent_depth = len(re.match(RE_YAML_INDENT, line).groups()[0])
         line = line.strip()
@@ -369,7 +380,6 @@ def _schemapath_for_cloudconfig(config, original_content):
             if path_prefix and path_prefix.endswith(previous_list_idx):
                 path_prefix = path_prefix[: -len(previous_list_idx)]
             key = str(list_index)
-            schema_line_numbers[key] = line_number
             item_indent = len(re.match(RE_YAML_INDENT, line[1:]).groups()[0])
             item_indent += 1  # For the leading '-' character
             previous_depth = indent_depth
@@ -380,7 +390,7 @@ def _schemapath_for_cloudconfig(config, original_content):
             # Process non-list lines setting value if present
             list_index = 0
             key, value = line.split(":", 1)
-        if path_prefix:
+        if path_prefix and indent_depth > previous_depth:
             # Append any existing path_prefix for a fully-pathed key
             key = path_prefix + "." + key
         while indent_depth <= previous_depth:
@@ -409,10 +419,17 @@ def _get_property_type(property_dict: dict) -> str:
     jsonschema.
     """
     property_type = property_dict.get("type")
-    if property_type is None and property_dict.get("enum"):
-        property_type = [
-            str(_YAML_MAP.get(k, k)) for k in property_dict["enum"]
-        ]
+    if property_type is None:
+        if property_dict.get("enum"):
+            property_type = [
+                str(_YAML_MAP.get(k, k)) for k in property_dict["enum"]
+            ]
+        elif property_dict.get("oneOf"):
+            property_type = [
+                subschema["type"]
+                for subschema in property_dict.get("oneOf")
+                if subschema.get("type")
+            ]
     if isinstance(property_type, list):
         property_type = "/".join(property_type)
     items = property_dict.get("items", {})
@@ -449,7 +466,7 @@ def _parse_description(description, prefix) -> str:
     return description
 
 
-def _get_property_doc(schema: dict, prefix="    ") -> str:
+def _get_property_doc(schema: dict, defs: dict, prefix="    ") -> str:
     """Return restructured text describing the supported schema properties."""
     new_prefix = prefix + "    "
     properties = []
@@ -460,6 +477,10 @@ def _get_property_doc(schema: dict, prefix="    ") -> str:
 
     for props in property_keys:
         for prop_key, prop_config in props.items():
+            if "$ref" in prop_config:
+                # Update the defined references in subschema for doc rendering
+                ref = defs[prop_config["$ref"].replace("#/$defs/", "")]
+                prop_config.update(ref)
             # Define prop_name and description for SCHEMA_PROPERTY_TMPL
             description = prop_config.get("description", "")
 
@@ -478,7 +499,9 @@ def _get_property_doc(schema: dict, prefix="    ") -> str:
                 if isinstance(items, list):
                     for item in items:
                         properties.append(
-                            _get_property_doc(item, prefix=new_prefix)
+                            _get_property_doc(
+                                item, defs=defs, prefix=new_prefix
+                            )
                         )
                 elif isinstance(items, dict) and (
                     items.get("properties") or items.get("patternProperties")
@@ -490,14 +513,16 @@ def _get_property_doc(schema: dict, prefix="    ") -> str:
                     )
                     new_prefix += "    "
                     properties.append(
-                        _get_property_doc(items, prefix=new_prefix)
+                        _get_property_doc(items, defs=defs, prefix=new_prefix)
                     )
             if (
                 "properties" in prop_config
                 or "patternProperties" in prop_config
             ):
                 properties.append(
-                    _get_property_doc(prop_config, prefix=new_prefix)
+                    _get_property_doc(
+                        prop_config, defs=defs, prefix=new_prefix
+                    )
                 )
     return "\n\n".join(properties)
 
@@ -520,15 +545,18 @@ def _get_examples(meta: MetaSchema) -> str:
     return rst_content
 
 
-def get_meta_doc(meta: MetaSchema, schema: dict) -> str:
+def get_meta_doc(meta: MetaSchema, schema: dict = None) -> str:
     """Return reStructured text rendering the provided metadata.
 
     @param meta: Dict of metadata to render.
+    @param schema: Optional module schema, if absent, read global schema.
     @raise KeyError: If metadata lacks an expected key.
     """
 
+    if schema is None:
+        schema = get_schema()
     if not meta or not schema:
-        raise ValueError("Expected meta and schema")
+        raise ValueError("Expected non-empty meta and schema")
     keys = set(meta.keys())
     expected = set(
         {
@@ -557,8 +585,11 @@ def get_meta_doc(meta: MetaSchema, schema: dict) -> str:
 
     # cast away type annotation
     meta_copy = dict(deepcopy(meta))
+    defs = schema.get("$defs", {})
+    if defs.get(meta["id"]):
+        schema = defs.get(meta["id"])
     try:
-        meta_copy["property_doc"] = _get_property_doc(schema)
+        meta_copy["property_doc"] = _get_property_doc(schema, defs=defs)
     except AttributeError:
         LOG.warning("Unable to render property_doc due to invalid schema")
         meta_copy["property_doc"] = ""
@@ -593,7 +624,7 @@ def load_doc(requested_modules: list) -> str:
     for mod_name in all_modules:
         if "all" in requested_modules or mod_name in requested_modules:
             (mod_locs, _) = importer.find_module(
-                mod_name, ["cloudinit.config"], ["schema"]
+                mod_name, ["cloudinit.config"], ["meta"]
             )
             if mod_locs:
                 mod = importer.import_module(mod_locs[0])
@@ -602,14 +633,34 @@ def load_doc(requested_modules: list) -> str:
 
 
 def get_schema() -> dict:
-    """Return jsonschema coalesced from all cc_* cloud-config module."""
-    full_schema = {
-        "$schema": "http://json-schema.org/draft-04/schema#",
-        "id": "cloud-config-schema",
-        "allOf": [],
-    }
+    """Return jsonschema coalesced from all cc_* cloud-config modules."""
+    schema_file = os.path.join(
+        os.path.dirname(os.path.abspath(__file__)), "cloud-init-schema.json"
+    )
+    full_schema = None
+    try:
+        full_schema = json.loads(load_file(schema_file))
+    except Exception as e:
+        LOG.warning("Cannot parse JSON schema file %s. %s", schema_file, e)
+    if not full_schema:
+        LOG.warning(
+            "No base JSON schema files found at %s."
+            " Setting default empty schema",
+            schema_file,
+        )
+        full_schema = {
+            "$defs": {},
+            "$schema": "http://json-schema.org/draft-04/schema#",
+            "allOf": [],
+        }
 
+    # TODO( Drop the get_modules loop when all legacy cc_* schema migrates )
+    # Supplement base_schema with any legacy modules which still contain a
+    # "schema" attribute. Legacy cc_* modules will be migrated to use the
+    # store module schema in the composite cloud-init-schema-<version>.json
+    # and will drop "schema" at that point.
     for (_, mod_name) in get_modules().items():
+        # All cc_* modules need a "meta" attribute to represent schema defs
         (mod_locs, _) = importer.find_module(
             mod_name, ["cloudinit.config"], ["schema"]
         )