slapconfiguration: Add .jsonschema recipe

[slapconfiguration]
<= slap-connection
recipe = slapos.cookbook:slapconfiguration.jsonschema
jsonschema = ${buildout:directory}/software.cfg.json

setup.py

@@ -152,6 +152,7 @@ setup(name=name,
           'simplehttpserver = slapos.recipe.simplehttpserver:Recipe',
           'slapconfiguration = slapos.recipe.slapconfiguration:Recipe',
           'slapconfiguration.serialised = slapos.recipe.slapconfiguration:Serialised',
+          'slapconfiguration.jsonschema = slapos.recipe.slapconfiguration:JsonSchema',
           'slapconfiguration.jsondump = slapos.recipe.slapconfiguration:JsonDump',
           'squid = slapos.recipe.squid:Recipe',
           'sshkeys_authority = slapos.recipe.sshkeys_authority:Recipe',

slapos/recipe/slapconfiguration.py

@@ -29,13 +29,20 @@ import json
 import logging
 import os
 
+import jsonschema
 import slapos.slap
 from slapos.recipe.librecipe import unwrap
 import six
 from six.moves.configparser import RawConfigParser
 from netaddr import valid_ipv4, valid_ipv6
-from slapos.util import mkdir_p
+from slapos.util import (
+  mkdir_p,
+  SoftwareReleaseSchema,
+  SoftwareReleaseSerialisation,
+  SoftwareReleaseSchemaValidationError,
+)
 from slapos import format as slapformat
+from zc.buildout import UserError
 
 
 logger = logging.getLogger("slapos")
@@ -263,6 +270,55 @@ class Serialised(Recipe):
       else:
           return {}
 
+class JsonSchema(Recipe):
+  """
+  Input:
+    jsonschema
+      JSON Schema for the SR.
+      All instance schemas must be available at the advertised relative paths.
+      Example:
+        ${buildout:directory}/software.cfg.json
+  """
+  def _schema(self, options):
+    path = options['jsonschema']
+    # because SoftwareReleaseSchema accepts only file:// paths
+    path = path if path.startswith('file://') else 'file://' + path
+    # because SoftwareReleaseSchema expects the SR url and adds .json
+    path = path[:-5] if path.endswith('.json') else path
+    return SoftwareReleaseSchema(path, options['slap-software-type'])
+
+  def _validator_for(self, schema):
+    # adapted from https://python-jsonschema.readthedocs.io/en/stable/faq
+    validator_cls = jsonschema.validators.validator_for(schema)
+    validate_original = validator_cls.VALIDATORS["properties"]
+    def validate_with_defaults(validator, properties, instance, schema):
+      # Set defaults
+      for key, subschema in properties.items():
+        if "default" in subschema:
+          instance.setdefault(key, subschema["default"])
+      # Call original properties validator
+      for error in validate_original(validator, properties, instance, schema):
+        yield error
+    # Extend validator class with extended properties validator
+    return jsonschema.validators.extend(
+        validator_cls, {"properties" : validate_with_defaults})
+
+  def _expandParameterDict(self, options, parameter_dict):
+    software_schema = self._schema(options)
+    serialisation = software_schema.getSerialisation(strict=True)
+    instance_schema = software_schema.getInstanceRequestParameterSchema()
+    if serialisation == SoftwareReleaseSerialisation.JsonInXml:
+      parameter_dict = unwrap(parameter_dict)
+    instance = parameter_dict if isinstance(parameter_dict, dict) else {}
+    validator = self._validator_for(instance_schema)(instance_schema)
+    errors = list(validator.iter_errors(instance))
+    if errors:
+      err = SoftwareReleaseSchemaValidationError(errors).format_error(indent=2)
+      msg = "Invalid parameters:\n" + err
+      raise UserError(msg)
+    options['configuration'] = instance
+    return instance
+
 class JsonDump(Recipe):
   def __init__(self, buildout, name, options):
     parameter_dict = self.fetch_parameter_dict(options)