Right way to update customData on old VMs in VMSS

[SnowmanCharles]

I'm recently playing with Azure VMSS and I have a case here:

1. I pass a customdata in osProfile when creating the VMSS.
2. I then updated the customdata in osProfile. But seems old VMs will not receive that.
3. I do reimage on the old VMs. Seems like the customdata was not renewed on old VMs.

My questions are:

1. Is osProfile.customData considered as part of VMSS model?
2. What's the right way to update the customData on my old VMs? Probably need something else besides a single reimage?

[fitzgeraldsteele]

@SnowmanCharles Apologies for letting this go so long! Yes, customData is part of the VMSS model -- you can update custom data / cloud init on scale sets via REST API
• Existing instances need to be updated to the latest model AND reimaged to have the new cloud-init run
• New instances will run the new cloud init