title: How to call Simple Systems Manager 'send_command' from within AWS Lambda Python
body: <p>I've got an AWS Simple Systems Manager document set up, that I'm trying to trigger from AWS Lambda using Python 2.7.</p>
  
  <p>My call looks like this:</p>
  
  <pre><code>ssmCommand = ssm.send_command(
      Targets = [
          {'Key': 'tag:Backup', 
                  'Values': [
                      'db']
                   }
                ],
      DocumentName = 'set-backup-mode-begin',
      TimeoutSeconds = 240,
      Comment = 'Set Backup Mode',
      Parameters = {},)
  </code></pre>
  
  <p>But, nothing happens.  I think the problem is here:</p>
  
  <pre><code>Targets = [
      {'Key': 'tag:Backup', 
              'Values': [
                  'db']
               }
            ]
  </code></pre>
  
  <p>Currently, there is exactly one instance with tag "Backup" and value of "db".  (If I can get this to work, there will be many more, but for now, just one.)</p>
  
  <p>I think (maybe?), I'm doing something wrong, and the <code>Targets</code> is getting defined as null, so nothing happens?  It appears to be syntactically correct.  (It compiles and runs, but nothing happens.)</p>
  
  <p>I'm brand new to Python and AWS Lambda.  Can someone offer a suggestion?</p>