Does chart support numeric conversion tuple syntax?

[ygqygq2]

values.yaml like this:

replica: 3

I want a list or tuple between zero and three, then I can use range to do someting.
0 1 2

How to writer in chart?

[mattfarina]

Helm uses the go template syntax. range is part of that. You can read about it in the go documentation (e.g., https://golang.org/pkg/text/template/). Does that help?

[ygqygq2]

@mattfarina I've read it, but there's no range loop like I said.So I'm here to ask for help.

[mattfarina]

Half way through the variables section it touches on range. See https://golang.org/pkg/text/template/#hdr-Variables. Does that not work for you?

[ygqygq2]

@mattfarina Thanks.
I mean, if give a number 3, then can get a list [0, 1, 2].

[mattfarina]

I think you want something like a loop. I am not sure of a way to do that today. It might be a good function for Sprig, the template function package Helm uses.

[bacongobbler]

yeah, bash has a command called seq that takes a number and returns a sequence of numbers up to and including that number, starting at 1: http://tldp.org/LDP/abs/html/extmisc.html

You can also define the intervals using three arguments: seq $BEGIN $INTERVAL $END. seq 0 1 3 would return the list 0 1 2 3, whereas seq 0 2 10 would return 0 2 4 6 8 10.

I think a function that performs similar to seq would be a great enhancement to sprig.

For the time being, you can use list 0 1 2 to achieve the same effect.

[ygqygq2]

@mattfarina @bacongobbler Thanks a lot.
Yes, your are right.
http://masterminds.github.io/sprig/integer_slice.html

{{ untilStep 0 3 1 }} can get [0 1 2]

[bacongobbler]

I filed Masterminds/sprig#124 to track this upstream. If you feel like contributing that function @ygqygq2, we'd really appreciate a PR.

[lentil1016]

{{ untilStep 0 3 1 }} works for now.

{{- range untilStep 0 3 1 }}
metadata:
  name: container-{{ . }}
---
{{- end }}

will produce

metadata:
  name: container-0
---
metadata:
  name: container-1
---
metadata:
  name: container-2
---

I wonder if it's a good idea to add this example to control_structures.md. It seems sort of a commonly used looping form to me. 🤔

[dominik-ba]

For me it looks like this does not work with values.
This example just prints out ports: and nothing else ...

ports:
  {{- range untilStep (int .Values.ports.start) (int .Values.ports.end) 1 }}
  - containerPort: {{ . }}
  protocol: TCP
  {{- end }}

values.yaml contains this

ports:
  start: 6000
  stop: 7000

Am I doing something wrong or is this not supported?

[ygqygq2]

@dominik-ba

[dominik-ba]

Ok that was embarrassing... :D thanks alot!
Maybe it would be good if there was an error instead of nothing printed in this case...
Thanks anyways :)