title: Azure VM creation fails because of invalid username
body: <p>I'm trying to create a new <strong>Docker for Azure CE VM</strong> in the portal.</p>
  
  <p>I configure all the settings as appropriate, using an <code>Authentication type</code> of <code>Password</code>.</p>
  
  <p>However it always fails to deploy, always with this error:</p>
  
  <p><code>{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-debug for usage details.","details":[{"code":"Conflict","message":"{\r\n \"status\": \"Failed\",\r\n \"error\": {\r\n \"code\": \"ResourceDeploymentFailure\",\r\n \"message\": \"The resource operation completed with terminal provisioning state 'Failed'.\",\r\n \"details\": [\r\n {\r\n \"code\": \"OSProvisioningClientError\",\r\n \"message\": \"Username specified for the VM is invalid for this Linux distribution. Error details: (000004)Failed to handle ovf-env.xml: (000007)Failed to create user account:waterloo, retcode:127, output:/bin/sh: useradd: not found\\n.\"\r\n }\r\n ]\r\n }\r\n}"}]}
  </code></p>
  
  <p>The <code>User name</code> I set this time was <code>waterloo</code>, but it has also failed to work with every other User name I've tried.</p>
  
  <p>So, what Linux distribution is it using and what is the username policy?</p>
  
  <p>-</p>
  
  <p><em>Apologies if this is very obvious, or I've referred to things incorrectly, I've only just started trying to learn Azure. Currently I'm evaluating if Azure or AWS is the way to go for my project.</em></p>
  
  <p><em>Thank you!</em></p>