From 94ba2e68bdca09a48114723eedb40d38a75b6ba6 Mon Sep 17 00:00:00 2001
From: Steve Pulec <spulec@gmail.com>
Date: Fri, 13 Apr 2018 15:05:13 -0400
Subject: [PATCH] SSM SendCommand InstanceIds are optional. Closes #1534.

---
 moto/ssm/models.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/moto/ssm/models.py b/moto/ssm/models.py
index af450e39e..bb25baa5f 100644
--- a/moto/ssm/models.py
+++ b/moto/ssm/models.py
@@ -142,7 +142,7 @@ class SimpleSystemManagerBackend(BaseBackend):
         return self._resource_tags[resource_type][resource_id]
 
     def send_command(self, **kwargs):
-        instances = kwargs['InstanceIds']
+        instances = kwargs.get('InstanceIds', [])
         now = datetime.datetime.now()
         expires_after = now + datetime.timedelta(0, int(kwargs['TimeoutSeconds']))
         return {