Fixes#4815
This implements the following steps:
* machine configuration updates
* pulling and unpacking system extension images
* validating, listing system extensions
* re-packing system extensions
* preserving installed extensions in `/etc/extensions.yaml`
Once extension is enabled, raw information can be queried with:
```
$ talosctl -n 172.20.0.2 cat /etc/extensions.yaml
layers:
- image: 000.ghcr.io-smira-gvisor-c927b54-dirty.sqsh
metadata:
name: gvisor
version: 20220117.0-v1.0.0
author: Andrew Rynhard
description: |
This system extension provides gVisor using containerd's runtime handler.
compatibility:
talos:
version: '> v0.15.0-alpha.1'
```
This was tested with the `gvisor` system extension.
Signed-off-by: Andrey Smirnov <andrey.smirnov@talos-systems.com>
