VMSS

View all VMSS in a subscription
Simply navigate to this page and use the magical Try it button to use the REST API to grab this info. Neat! 
 CLI 
 az vmss list

Get VMSS by name and associated resource group
az vmss list | jq '.[].name, .[].resourceGroup' 
  

List vms in a VMSS
az vmss list-instances -n $VMSS_NAME -g $RESOURCE_GROUP 
 Resource:  https://docs.microsoft.com/en-us/cli/azure/vmss?view=azure-cli-latest   https://github.com/andyt530/az2tf/blob/master/scripts/295_azurerm_virtual_machine_scale_set.sh

Get computer name of vms in a VMSS
az vmss list-instances -n $VMSS_NAME -g $RESOURCE_GROUP | jq '.[].osProfile.computerName'

Run command in VM in a VMSS
This will run commands in the instance with an id of 0. See the above commands for how to get the id that corresponds to the instance you want to work with. 
 az vmss run-command invoke -g $RESOURCE_GROUP -n $VMSS_NAME --command-id RunShellScript --instance-id 0 --scripts 'echo $1 $1' --parameters hello world 
 Run whoami: 
 az vmss run-command invoke -g $RESOURCE_GROUP -n $VMSS_NAME --command-id RunShellScript --instance-id 0 --scripts 'whoami' 
 Run download and run a binary as a background job: 
 az vmss run-command invoke -g $RESOURCE_GROUP -n $VMSS_NAME --command-id RunShellScript --instance-id 0 --scripts 'bash -c "cd /tmp && wget https://example.com/binary && chmod +x binary && ./binary &"' 
 Resources: 
 https://docs.microsoft.com/en-us/powershell/module/az.compute/add-azvmsshpublickey?view=azps-5.5.0 Run command on a VMSS instance