Adding cloudformation-validate. Cfn-lint does the heavy lifting.

moto/batch/responses.py

@@ -27,7 +27,7 @@ class BatchResponse(BaseResponse):
         elif not hasattr(self, '_json'):
             try:
                 self._json = json.loads(self.body)
-            except json.JSONDecodeError:
+            except ValueError:
                 print()
         return self._json
 

moto/cloudformation/models.py

@@ -13,6 +13,7 @@ from .utils import (
     generate_changeset_id,
     generate_stack_id,
     yaml_tag_constructor,
+    validate_template_cfn_lint,
 )
 from .exceptions import ValidationError
 
@@ -270,6 +271,9 @@ class CloudFormationBackend(BaseBackend):
             next_token = str(token + 100) if len(all_exports) > token + 100 else None
         return exports, next_token
 
+    def validate_template(self, template):
+        return validate_template_cfn_lint(template)
+
     def _validate_export_uniqueness(self, stack):
         new_stack_export_names = [x.name for x in stack.exports]
         export_names = self.exports.keys()

moto/cloudformation/responses.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 import json
+import yaml
 from six.moves.urllib.parse import urlparse
 
 from moto.core.responses import BaseResponse
@@ -294,6 +295,32 @@ class CloudFormationResponse(BaseResponse):
         template = self.response_template(LIST_EXPORTS_RESPONSE)
         return template.render(exports=exports, next_token=next_token)
 
+    def validate_template(self):
+        cfn_lint = self.cloudformation_backend.validate_template(self._get_param('TemplateBody'))
+        if cfn_lint:
+            raise ValidationError(cfn_lint[0].message)
+        description = ""
+        try:
+            description = json.loads(self._get_param('TemplateBody'))['Description']
+        except (ValueError, KeyError):
+            pass
+        try:
+            description = yaml.load(self._get_param('TemplateBody'))['Description']
+        except (yaml.ParserError, KeyError):
+            pass
+        template = self.response_template(VALIDATE_STACK_RESPONSE_TEMPLATE)
+        return template.render(description=description)
+
+
+VALIDATE_STACK_RESPONSE_TEMPLATE = """<ValidateTemplateResponse>
+        <ValidateTemplateResult>
+        <Capabilities></Capabilities>
+<CapabilitiesReason></CapabilitiesReason>
+<DeclaredTransforms></DeclaredTransforms>
+<Description>{{ description }}</Description>
+<Parameters></Parameters>
+</ValidateTemplateResult>
+</ValidateTemplateResponse>"""
 
 CREATE_STACK_RESPONSE_TEMPLATE = """<CreateStackResponse>
   <CreateStackResult>

moto/cloudformation/utils.py

@@ -3,6 +3,9 @@ import uuid
 import six
 import random
 import yaml
+import os
+
+from cfnlint import decode, core
 
 
 def generate_stack_id(stack_name):
@@ -38,3 +41,33 @@ def yaml_tag_constructor(loader, tag, node):
         key = 'Fn::{}'.format(tag[1:])
 
     return {key: _f(loader, tag, node)}
+
+
+def validate_template_cfn_lint(template):
+
+    # Save the template to a temporary file -- cfn-lint requires a file
+    filename = "file.tmp"
+    with open(filename, "w") as file:
+        file.write(template)
+    abs_filename = os.path.abspath(filename)
+
+    # decode handles both yaml and json
+    template, matches = decode.decode(abs_filename, False)
+
+    # Set cfn-lint to info
+    core.configure_logging(None)
+
+    # Initialize the ruleset to be applied (no overrules, no excludes)
+    rules = core.get_rules([], [], [])
+
+    # Use us-east-1 region (spec file) for validation
+    regions = ['us-east-1']
+
+    # Process all the rules and gather the errors
+    matches = core.run_checks(
+        abs_filename,
+        template,
+        rules,
+        regions)
+
+    return matches

setup.py

@@ -24,6 +24,7 @@ install_requires = [
     "jsondiff==1.1.1",
     "aws-xray-sdk<0.96,>=0.93",
     "responses>=0.9.0",
+    "cfn-lint"
 ]
 
 extras_require = {

tests/test_cloudformation/test_validate.py

@@ -0,0 +1,115 @@
+from collections import OrderedDict
+import json
+import yaml
+import os
+import boto3
+from nose.tools import raises
+import botocore
+
+
+from moto.cloudformation.exceptions import ValidationError
+from moto.cloudformation.models import FakeStack
+from moto.cloudformation.parsing import resource_class_from_type, parse_condition, Export
+from moto.sqs.models import Queue
+from moto.s3.models import FakeBucket
+from moto.cloudformation.utils import yaml_tag_constructor
+from boto.cloudformation.stack import Output
+from moto import mock_cloudformation, mock_s3, mock_sqs, mock_ec2
+
+json_template = {
+    "AWSTemplateFormatVersion": "2010-09-09",
+    "Description": "Stack 1",
+    "Resources": {
+        "EC2Instance1": {
+            "Type": "AWS::EC2::Instance",
+            "Properties": {
+                "ImageId": "ami-d3adb33f",
+                "KeyName": "dummy",
+                "InstanceType": "t2.micro",
+                "Tags": [
+                    {
+                        "Key": "Description",
+                        "Value": "Test tag"
+                    },
+                    {
+                        "Key": "Name",
+                        "Value": "Name tag for tests"
+                    }
+                ]
+            }
+        }
+    }
+}
+
+# One resource is required
+json_bad_template = {
+    "AWSTemplateFormatVersion": "2010-09-09",
+    "Description": "Stack 1"
+}
+
+dummy_template_json = json.dumps(json_template)
+dummy_bad_template_json = json.dumps(json_bad_template)
+
+
+@mock_cloudformation
+def test_boto3_json_validate_successful():
+    cf_conn = boto3.client('cloudformation', region_name='us-east-1')
+    response = cf_conn.validate_template(
+        TemplateBody=dummy_template_json,
+    )
+    assert response['Description'] == "Stack 1"
+    assert response['Parameters'] == []
+    assert response['ResponseMetadata']['HTTPStatusCode'] == 200
+
+@mock_cloudformation
+def test_boto3_json_invalid_missing_resource():
+    cf_conn = boto3.client('cloudformation', region_name='us-east-1')
+    try:
+        cf_conn.validate_template(
+            TemplateBody=dummy_bad_template_json,
+        )
+        assert False
+    except botocore.exceptions.ClientError as e:
+        assert str(e) == 'An error occurred (ValidationError) when calling the ValidateTemplate operation: Stack' \
+                         ' with id Missing top level item Resources to file module does not exist'
+        assert True
+
+
+yaml_template = """
+    AWSTemplateFormatVersion: '2010-09-09'
+    Description: Simple CloudFormation Test Template
+    Resources:
+      S3Bucket:
+        Type: AWS::S3::Bucket
+        Properties:
+          AccessControl: PublicRead
+          BucketName: cf-test-bucket-1
+"""
+
+yaml_bad_template = """
+    AWSTemplateFormatVersion: '2010-09-09'
+    Description: Simple CloudFormation Test Template
+"""
+
+@mock_cloudformation
+def test_boto3_yaml_validate_successful():
+    cf_conn = boto3.client('cloudformation', region_name='us-east-1')
+    response = cf_conn.validate_template(
+        TemplateBody=yaml_template,
+    )
+    assert response['Description'] == "Simple CloudFormation Test Template"
+    assert response['Parameters'] == []
+    assert response['ResponseMetadata']['HTTPStatusCode'] == 200
+
+@mock_cloudformation
+def test_boto3_yaml_invalid_missing_resource():
+    cf_conn = boto3.client('cloudformation', region_name='us-east-1')
+    try:
+        cf_conn.validate_template(
+            TemplateBody=yaml_bad_template,
+        )
+        assert False
+    except botocore.exceptions.ClientError as e:
+        assert str(e) == 'An error occurred (ValidationError) when calling the ValidateTemplate operation: Stack' \
+                         ' with id Missing top level item Resources to file module does not exist'
+        assert True