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

1 files changed, 69 insertions, 0 deletions

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" }
+  ]
+}