is there any way to templating a date of a fixed day of the week?

[lzecca78]

Hi! This is not an issue, but just a question regarding something I would like to configure in the helm template.
As per documentation, kube-janitor allows to specify a label to resource janitor/expires: 23-06-23T23:59:00Z. This label will enable kube-janitor to delete it.
I would like to configure with helm template the value of the time that is the next Friday at 23:59. I've seen the documentation of helm but even with date_modify seems not possible to make something like this: date -d 'next Friday' '+%y-%m-%dT23:59:00Z'. This is very useful for feature branch namespaces/resources that in our case, has an expiration date.
Does anyone have any suggestions for this?
Thanks in advance!

[gjenkins8]

You could use date math e.g. https://www.almanac.com/how-find-day-week to work out the current day of the week. Then you just need to add the desired number of days to the current date. I don't imagine this math will look pretty in helm templating. But probably doable.

[lzecca78]

@gjenkins8 probably i did it, was far from being easy but this is what looks like:

{{ $current_date := now | date "06-01-02-4-3" }}
{{ $splitted_date := split "-" $current_date }}
{{ $current_year := $splitted_date._0 }}
{{ $current_month := $splitted_date._1 }}
{{ $current_day := $splitted_date._2 }}
{{ $current_hour := $splitted_date._4 }}
{{ $year_code := mod ( add $current_year (div $current_year 4)) 7 }}
{{ $month_codes:= dict "01" "0" "02" "3" "03" "3" "04" "6" "05" "1" "06" "4" "07" "6" "08" "2" "09" "5" "10" "0" "11" "3" "12" "5" }}
{{ $current_month_code := get $month_codes $current_month }}
{{ $century_code := 6 }}
{{ $mod_400_current_year := mod $current_year 400 }}
{{ $mod_100_current_year := mod $current_year 100 }}
{{ $mod_4_current_year := mod $current_year 4 }}
{{ $leap_year := "niente" }}
{{ if and (eq $mod_400_current_year 0) (eq $mod_100_current_year 0) }}
{{ $leap_year = 1 }}
{{ else if  and (eq $mod_4_current_year 0) (ne $mod_100_current_year 0) }}
{{ $leap_year = 1 }}
{{ else }}
{{ $leap_year = 0 }}
{{ end }}
{{ $current_day_of_the_week := mod (sub ( add $year_code $current_month_code  $century_code $current_day) $leap_year) 7  }}
{{ $missing_days_to_next_friday := sub  5 $current_day_of_the_week }}
{{ $missing_hours_to_midnight :=  sub 23 $current_hour }}
janitor_annotations value: {{ now | date_modify (printf "+%vh" ( add ( mul $missing_days_to_next_friday 24)  $missing_hours_to_midnight))  | date "2006-01-02T15:04:05Z" }}

probably it could be improved for sure, but at least is a starting point.
I've tried it here: https://helm-playground.com/

[gjenkins8]

heh, very nice! (or, as about as beautiful as I imagined :) )

[lzecca78]

yeah, i've fixed something, and moved the content into a function in _helpers.tpl :

{{- define "mychart.label-ns-next-friday-janitor" -}}
{{- $current_date := now | date "06-01-02-T15" }}
{{- $splitted_date := split "-" $current_date }}
{{- $current_year := $splitted_date._0 }}
{{- $current_month := $splitted_date._1 }}
{{- $current_day := $splitted_date._2 }}
{{- $current_hour := $splitted_date._3 | replace "T" "" }}
{{- $year_code := mod ( add $current_year (div $current_year 4)) 7 }}
{{- $month_codes:= dict "01" "0" "02" "3" "03" "3" "04" "6" "05" "1" "06" "4" "07" "6" "08" "2" "09" "5" "10" "0" "11" "3" "12" "5" }}
{{- $current_month_code := get $month_codes $current_month }}
{{- $century_code := 6 }}
{{- $mod_400_current_year := mod $current_year 400 }}
{{- $mod_100_current_year := mod $current_year 100 }}
{{- $mod_4_current_year := mod $current_year 4 }}
{{- $leap_year := "nil" }}
{{- if and (eq $mod_400_current_year 0) (eq $mod_100_current_year 0) }}
{{- $leap_year = 1 }}
{{- else if  and (eq $mod_4_current_year 0) (ne $mod_100_current_year 0) }}
{{- $leap_year = 1 }}
{{- else }}
{{- $leap_year = 0 }}
{{- end }}
{{- $current_day_of_the_week := mod (sub ( add $year_code $current_month_code  $century_code $current_day) $leap_year) 7  }}
{{- $missing_days_to_next_friday := "nil" }}
{{- if le $current_day_of_the_week 5 }}
{{- $missing_days_to_next_friday = sub  5 $current_day_of_the_week }}
{{- else if eq $current_day_of_the_week 6 }}
{{- $missing_days_to_next_friday = add  6 $current_day_of_the_week }}
{{- else if eq $current_day_of_the_week 7 }}
{{- $missing_days_to_next_friday = add  5 $current_day_of_the_week }}
{{- end }}
{{- $missing_hours_to_midnight :=  sub 23 $current_hour }}
{{- $exptected_date :=  now | date_modify (printf "+%vh" ( add ( mul $missing_days_to_next_friday 24) $missing_hours_to_midnight ))  | date "2006-01-02T15:04:05Z" }}
{{- printf "%s" $exptected_date }}
{{- end }}

Now is still a lot of stuff, but at least is hided 🤣

[gjenkins8]

closing as completed, can reopen if desired