Reset resource without destroying/recreating

[eirslett]

Many providers have support for "restore from factory-settings"-like functionality, e.g. you can revert a machine state to a droplet image or ISO file, without destroying the resource itself. This could be useful to expose through Terraform (terraform reset my-server?) since in immutable infrastructure, you might want to reset a resource, but not lose its otherwise ephemeral properties, like its IP address, or the contents of a data disk which is separate from the boot disk.
(Not all providers support floating IPs and/or disk mounts separate from the resource itself)

[phinze]

Hi @eirslett - interesting idea!

At base, Terraform is just a driver for upstream API calls - so in order to model a feature like this we'd need to be able to express it as a sequence of operations.

I'm not aware of the equivalent API actions that would yield the sort of behavior you're talking about. Can you share an example?

[eirslett]

DigitalOcean has "Rebuild From Image" and "Rebuild from original" buttons, I'm sure they have an API for it as well, but I haven't checked too closely. SoftLayer has restore from image, and I'm pretty sure OpenStack has it as well. (Ok, so it's mostly guesswork, I don't have any proof of existence, but it would be reasonable)

[afeld]

taint is probably the best existing way to do this.

[paultyng]

In order to accomplish this you would still need something that "changed" in Terraform (ie. a throwaway version or something that caused this to invoke the upstream API), but as mentioned above, its not something that easily fits in to the Terraform model.

[ghost]

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