Consider using VMSS in the future

[zikalino]

Here's an example of creating VMSS / scaling up / deploying application.

https://github.com/Azure-Samples/ansible-playbooks/tree/master/vmss

I think this should be done once we are done with initial implementation
However we should find another way of deploying scripts as VM Extension operates on VMs directly.
Perhaps it would be possible to do it on VMs created by VMSS, but it doesn't sound like an ideal solution.

Actually, i have another idea how this could be done:

• we could have initial playbooks to just create and store images
• main script would just create 3 scalesets
• scaling up wouldn't require any additional steps on new vms

[zikalino]

@haroldwongms could you check and let me know what you think?
i think the first step (creating pre-prepared images) could be useful even in current setup, so we wouldn't have to run prep steps after vms are created.

[haroldwongms]

unfortunately, we cannot publish custom prepped RHEL images that are not entitled for public consumption.

[zikalino]

i meant having a script for customers, say prepare.yml that would prepare images for them.
then they would run create.yml using these images

[haroldwongms]

Also, OCP 3.9 does not support VMSS. We need to wait until 3.10 at the earliest and even then, we need to test to ensure this is working correctly.

[haroldwongms]

If we provide prepare.yml, we also need to provide instructions for creating the RHEL image, uploading the RHEL image and variablize the reference for the image versus using the on-demand RHEL image. It is doable.

[zikalino]

I assume that would be a part of the script, so no additional instructions would be needed. prepare.yml would just create a VM based on original RHEL image, run prep script, take snapshot, and destroy VM.