change drop-ins to drop_ins

[koflanx]

What this PR does / why we need it:
CoreOS Cloud Init is not reading the drop-ins sections in cloud-config.yml since Flatcar 3975.2.0.

Which issue(s) this PR fixes:
Fixes flatcar/Flatcar#1567

What type of PR is this?
/kind bug

Does this PR introduce a user-facing change? Then add your Release Note here:

NONE

Documentation:

NONE

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[adberger]

@koflanx Isn't this a bug as well?
Should be {{ if $unit.DropIns }} instead of {{ if $unit.Content }} imo.

[adberger]

@kron4eg Maybe you can give your 2 cents about this?

[kron4eg]

yeah, it's it definitely.

diff --git pkg/generator/generator.go pkg/generator/generator.go
index b158bcc..ac966fd 100644
--- pkg/generator/generator.go
+++ pkg/generator/generator.go
@@ -253,13 +253,13 @@ coreos:
 	command: start
 	{{- end }}
     mask: {{or $unit.Mask false}}
-{{ if $unit.Content }}
+{{ with $unit.Content }}
     content: |
-{{ $unit.Content | indent 6 }}
+{{ . | indent 6 }}
 {{- end }}
-{{ if $unit.Content }}
+{{ with $unit.DropIns }}
     drop_ins:
-{{- range $_, $dropIn := $unit.DropIns }}
+{{- range $_, $dropIn := . }}
       - name: "{{ $dropIn.Name }}"
         content: |
 {{ $dropIn.Content | indent 10 }}

This is how it should look like (using go's {{ with }} template operator to avoid such bugs in the future).

[adberger]

Is there anything missing for this MR to be merged?

[kron4eg]

Let's make a copy, for have both drop-ins: and drop_ins:. For backward compatibility 🤷‍♂️