refactor: remove bellows dep

[weafscast]

Partial fix for #11120

Motivation

The library used for this function was unmaintained, and since it's a simple util it's easier to write it on our own.

SideNote: This is a fresh set of code, doesn't import library so we are good with license here.

Modifications

• Added our own expansion and flattening util functions along with the tests
• removed bellow library from dependency.

Verification

Added unit test cases

[weafscast]

I am not sure if this needs a new issue all-together?

cc/ @agilgur5

[ryancurrah]

+1 for a little bit of copying.

[terrytangyuan]

Could you add a link to the reference implementation/original source?

[agilgur5]

+1 for a little bit of copying.

Personally, I'd rather not us maintain more, especially when we already lack contributors. Also the tool is tiny, so even if it is deprecated, we may not need any updates to it anyway.

It looks like Alex C opened a few issues in the bellow repo a few years ago, most notably doublerebel/bellows#9, pointing to this fork: https://github.com/integration-system/bellows

SideNote: This is a fresh set of code, doesn't import library so we are good with license here.

If you copied any code, then it would be under their license, but if not, then it'd be under Argo's

I am not sure if this needs a new issue all-together?

This is fine, I edited your description to reference the other issue

[weafscast]

Could you add a link to the reference implementation/original source?

There is no reference that i have used. I have made sure to run the test against this as well to make sure the behaviour matches. https://github.com/doublerebel/bellows

[weafscast]

Personally, I'd rather not us maintain more, especially when we already lack contributors. Also the tool is tiny, so even if it is deprecated, we may not need any updates to it anyway.

I would be slightly biased towards writing simple utils instead of using a library for the same as long as comprehensive test are there for util.

[isubasinghe]

With @agilgur5 on this one, lets keep bellows for now until expressions as a whole are tackled.

[weafscast]

I would slightly disagree here. I would rather have tested unmaintained code (what this PR would become in the worst case) than non-tested non-maintained code(the library that we use).

Independently we should merge this -> https://github.com/argoproj/argo-workflows/pull/13591/files#diff-193ec69866aa16c7ccb83764540afe3ddeea0b19cd2c268a17fb14b65bce5239

[agilgur5]

I would slightly disagree here. I would rather have tested unmaintained code (what this PR would become in the worst case) than non-tested non-maintained code(the library that we use).

It looks like Alex C opened a few issues in the bellow repo a few years ago, most notably doublerebel/bellows#9, pointing to this fork: https://github.com/integration-system/bellows

This fork has some tests. I didn't realize it didn't have tests, although that can be remedied in a fork

Independently we should merge this ->

Feel free to split it off into a separate PR

[isubasinghe]

@weafscast yeah I think adding the tests as an independent PR is something I would be okay with.

I do appreciate your contribution, its just that expressions need some rethinking and it doesn't make sense to make new changes (especially ones that may add more maintenance effort) to expressions related libraries when we don't know what the state of expressions would look like in the next 6 months or so.

[weafscast]

Splitted tests pr -> https://github.com/argoproj/argo-workflows/pull/13664/files

Closing this pr for the meanwhile.