Report Templates for Home Assistant, JSON and at Large

[fanuch]

Having the same needs as #1203 for notifications to be handled by Home Assistant, I've gone down the rabbit hole and have a means to potentially contribute to #1204

The ability to format messages in JSON template would be really valuable for manipulation down-stream.

My apologies as my go is quite underdeveloped but I came up with this go template solution:

template='
[
    {{ $len := len .Entries }}
    {{range $idx, $e := .Entries }}
        {
            "level": "{{ $e.Level}}",
            "message": "{{ $e.Message}}"
            {{println}}
        }{{if ne ($idx) (Dec $len)}},{{end}}
    {{end}}
]'

and ran with the following as a test:

./watchtower \
    --notifications shoutrrr \
    --notification-url "$url" \
    --notification-template "$template" \
    --debug \
    --run-once \
    --no-pull \
    --notification-report \
    --monitor-only 

Which results in:

[
  {
    "level": "info",
    "message": "Watchtower v1.4.0-3-ga5c60a9"
  },
  {
    "level": "info",
    "message": "Using notifications: generic"
  },
  {
    "level": "info",
    "message": "Checking all containers (except explicitly disabled with label)"
  },
  {
    "level": "info",
    "message": "Running a one time update."
  }
]

Two notes

1. For some reason, rendering on {{ range . }} (as is every example) fails as Data.Report are returned as nil. This forced me to run {{ range .Entries }} instead.
2. I couldn't determine any way to avoid an extra , at the end of the JSON array which may be problematic. I had to add in my own template function for decrement so that the final loop index would be able to match the size of the slice. Simply added:

func getShoutrrrTemplate(tplString string, legacy bool) (tpl *template.Template, err error) {
	funcs := template.FuncMap{
		"ToUpper": strings.ToUpper,
		"ToLower": strings.ToLower,
		"Title":   strings.Title,
                // I added this part in
                "Dec": func(i int) int {
                    return i - 1
                 },
          }

What do you think? Is there a way to make this a little neater? Does this help with documenting the notification-report issue?

[piksel]

1. This is due to --notification-report which adds the .Report extra data to the template data (and moves the entries into .Entries). .Report is only populated at the end of a "Session", it then contains the number of containers checked/updated/failed etc.

2. You could add the comma at the start instead:

[
    {{range $idx, $e := .Entries }}
        {{if ne $idx 0)}},{{end}}{
            "level": "{{ $e.Level}}",
            "message": "{{ $e.Message}}"
            {{println}}
        }
    {{end}}
]

Thanks a lot for your effort, it does help a lot. Hopefully I will get time this or the next weekend to put together something. My idea is to basically mimic the Data struct in JSON, so it will be more like:

{ 
    "entries": [
        {{- range $idx, $e := .Entries -}}
        {{- if ne $idx 0 -}},{{- end}}
        {
            "level": "{{ $e.Level}}",
            "message": "{{ $e.Message}}"
        }{{end}}
    ],
    "report": {{if .Report -}}{{- with .Report -}}{
        scanned: {{len .Scanned}},
        updated: {{len .Updated}},
        failed: {{len .Failed}},
        skipped: {{len .Skipped}},
        stale: {{len .Stale}},
        fresh: {{len .Fresh}},
    }{{- end -}}{{- else -}}null{{- end}}
}

goplay link

I would like to include information about the containers as well though, but I haven't written that part yet.

[fanuch]

I'm happy I could help - even in a small way!

1. Thanks for explaining what happened on .Report - I was starting to thing I was doing something very wrong.
2. I'm dumb. That's a way better suggestion haha

Your rendered template looks amazing and I will definitely be using that 👍

I would like to include information about the containers as well though

That would be a good addition.

If you wouldn't mind pointing me to a stub I would be happy to start fleshing out some documentation around this as a PR to help others

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[piksel]

I still aim to do this at some point...

[evantaur]

spent a while trying to get this to work (Go is absolute mystery to me), not sure if this helps anyone else but here's what i did

it only sends updates and failed notifications in JSON payload:

{
  "title" : "watchtower",
  "message" : "updated the following containers:\n- container 1\n - container 2"
}

Template:

{{- if .Report -}}
 {{- with .Report -}}
  {{- if (or .Updated .Failed) -}} 
{ "title": "Watchtower", "message": "updated the following containers:\n{{- range .Updated }}\n- {{.Name}} ({{.ImageName}}): {{.CurrentImageID.ShortID}} updated to {{.LatestImageID.ShortID}}
   {{- end }}
   {{- if .Failed }}\n\nFailed to update:
    {{- range .Failed }}\n- {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}}
    {{- end }}
  {{- end - }}
" }
  {{- end -}}
 {{- end -}}
{{- end -}}

Edit: updated txt file since github absolutely butchered the formatting

docker.txt

[piksel]

I don't think this is mentioned in the docs, but if you put json.v1 as the template it will give you a JSON representation of the notification data.

Also you can use the template preview (alpha quality) to easier test your templates:
https://containrrr.dev/watchtower/template-preview/