Make putparameter behave more like the real endpoint does, respond with Version or ParameterAlreadyExists (#1464)

moto/ssm/models.py

@@ -126,6 +126,7 @@ class SimpleSystemManagerBackend(BaseBackend):
         last_modified_date = time.time()
         self._parameters[name] = Parameter(
             name, value, type, description, keyid, last_modified_date, version)
+        return version
 
     def add_tags_to_resource(self, resource_type, resource_id, tags):
         for key, value in tags.items():

moto/ssm/responses.py

@@ -162,9 +162,18 @@ class SimpleSystemManagerResponse(BaseResponse):
         keyid = self._get_param('KeyId')
         overwrite = self._get_param('Overwrite', False)
 
-        self.ssm_backend.put_parameter(
+        result = self.ssm_backend.put_parameter(
             name, description, value, type_, keyid, overwrite)
-        return json.dumps({})
+
+        if result is None:
+            error = {
+                '__type': 'ParameterAlreadyExists',
+                'message': 'Parameter {0} already exists.'.format(name)
+            }
+            return json.dumps(error), dict(status=400)
+
+        response = {'Version': result}
+        return json.dumps(response)
 
     def add_tags_to_resource(self):
         resource_id = self._get_param('ResourceId')

tests/test_ssm/test_ssm_boto3.py

@@ -97,12 +97,14 @@ def test_get_parameters_by_path():
 def test_put_parameter():
     client = boto3.client('ssm', region_name='us-east-1')
 
-    client.put_parameter(
+    response = client.put_parameter(
         Name='test',
         Description='A test parameter',
         Value='value',
         Type='String')
 
+    response['Version'].should.equal(1)
+
     response = client.get_parameters(
         Names=[
             'test'
@@ -115,11 +117,16 @@ def test_put_parameter():
     response['Parameters'][0]['Type'].should.equal('String')
     response['Parameters'][0]['Version'].should.equal(1)
 
+    try:
         client.put_parameter(
             Name='test',
             Description='desc 2',
             Value='value 2',
             Type='String')
+        raise RuntimeError('Should fail')
+    except botocore.exceptions.ClientError as err:
+        err.operation_name.should.equal('PutParameter')
+        err.response['Error']['Message'].should.equal('Parameter test already exists.')
 
     response = client.get_parameters(
         Names=[
@@ -134,13 +141,15 @@ def test_put_parameter():
     response['Parameters'][0]['Type'].should.equal('String')
     response['Parameters'][0]['Version'].should.equal(1)
 
-    client.put_parameter(
+    response = client.put_parameter(
         Name='test',
         Description='desc 3',
         Value='value 3',
         Type='String',
         Overwrite=True)
 
+    response['Version'].should.equal(2)
+
     response = client.get_parameters(
         Names=[
             'test'