[Question] Image/Instance templates: is it possible to parse variable as structural data in the template?

tregubovav · September 12, 2024, 12:51am

I’m looking for ability to extend images with additional templates and I would like to understand whether Incus daemon can pass the config variable as structured data (like lists and/or maps), or it passes all variables as plain strings.

tregubovav · September 13, 2024, 4:58am

My understanding after reviewing the code - config variables are passed to template as string values only

github.com

lxc/incus/blob/9a3ec959faf82ed35b972d661a6c078ce142fde2/internal/server/instance/drivers/driver_lxc.go#L7039


      
          			configGet := func(confKey, confDefault *pongo2.Value) *pongo2.Value {
          				val, ok := d.expandedConfig[confKey.String()]
          				if !ok {
          					return confDefault
          				}
          
          				return pongo2.AsValue(strings.TrimRight(val, "\r\n"))
          			}
          
          			// Render the template
          			err = tplRender.ExecuteWriter(pongo2.Context{"trigger": trigger,
          				"path":       tplPath,
          				"container":  containerMeta,
          				"instance":   containerMeta,
          				"config":     d.expandedConfig,
          				"devices":    d.expandedDevices,
          				"properties": tpl.Properties,
          				"config_get": configGet}, w)
          			if err != nil {
          				return err
          			}