Allow Hetzner Snapshots as base for a Snapshot build

[Nkmol]

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Description

Allow the possibility to apply a snapshot name as the input of a snapshot build. Currently, we only allow for a "OS image" as the base.

Use Case(s)

This would allow for sequential snapshot build, for example with the following chain: ISO Image Ubuntu → Snapshot server → snapshot server-special

Using the Source Build block, I believe, we could even build this chain as Packer build builds in-order of definition.

Potential configuration

There is no difference between 'input' and 'output' definitions, but maybe “base” (so “base_snapshot”) would be applicable both for images and snapshots.

source "hcloud" "server" {
  snapshot_name        = "server-special"
  server_type          = "cx11"
}

source "hcloud" "server-special" {
  snapshot_name        = "server-special"
  server_type          = "cx11"
}

build {
  sources = [
    "source.server"
  ]

  // ...
}

build {
  sources = [
    "source.server-special",
  ]

  source "hcloud.server-special" {
    base_snapshot         = "server"
  }
}

Potential References

• https://www.packer.io/docs/templates/hcl_templates/blocks/build/source
• https://github.com/hashicorp/packer/issues/9154#issuecomment-694153472

[Nkmol]

This is actually possible using the image_filter property, once you make sure to add a snapshot_labels as Snapshots do not have a "name" property.

Which is exactly what is described in the docs:

If you want to reference the image as a sample in your terraform configuration please use the image id or the snapshot_labels.